Batteries and inverters going off grid with solar. - Page 1
Forum section: electronics / general

author: Simon
author_rank: Unknown
timestamp: August 15, 2015, 10:43:36 am
content: I've always considered a home solar system. Due to the large expense of a professional system and political instabilities in solar I have shied away from a grid tied system where I sell back the power. The latest political move of our Conservative government to not only remove subsidies from renewables but to tax ecologically generated power has hardened my resolve to go off grid and do it my way rather than get tied in to the politics of the moment and what some company is offering me.Panels are not a problem. My main thing is that is batteries and inverters. Most items in my house would probably work of DC so a modified sine wave inverter would not be a problem things like my computers and LED lights. I also seem to have separate upstairs and downstairs circuits for both lights and sockets so I can easily distribute the load over smaller inverters. The only thing I can think of for things like my fridge and perhaps microwave is to use a dedicated pure sine wave inverter. That way I spend the money just where it's needed and get a cheaper inverter for other stuff.The next thing is batteries, these will probably be the first thing I need to buy and I am uncertain as to which voltage to work with. Below are the voltage the more batteries in parallel I will need or the larger single batteries will need to be. If I can work from say 100 V then even 110 amp leisure batteries would easily give me a 5 kW storage capacity.I also need to give some consideration to wiring up, I cannot go completely off grid as I doubt I would be able to generate enough so I would need it ability to switch over. It ability to switch over automatically would be good unfortunately that would require running wires from the back of my house to the front and modifying my distribution box to put in switchover relays and perhaps devised some sort of under voltage mechanism for the batteries so that the inverters cut out before the batteries are damaged. I expect that to be relatively easy as all I need do is detect the voltage on the batteries and turn inverters off. If the inverters or the battery management are powering a relay relay could hold the system on and once released remain on the grid until I manually switch back over.I think inverters are my main concern as they will drive the rest of the system but I need to forward plan as I will need to bite the batteries first.I don't want to spend a fortune on inverters but I don't want to buy cheap rubbish.

author: bookaboo
author_rank: Frequent Contributor
timestamp: August 15, 2015, 10:57:00 am
content: I suggest getting a comfy chair and a marathon of Martin Lortons videos, he covers a lot of what you have asked. Good inverters will cost and I'd stick to pure sine for everything, I would however suggest sharing loads across a few different units, that way when one goes bang you still have some functionality.I have a similar project in mind for a few years time, I'm going to research the feasibility of having a DC bus for lower loads... I think having an inverter drive a bunch of switchmode powersupplies (for example LED lights, TV, PC, Laptop, Chargers etc) is probably a bit wasteful and adds two levels of complexity. The efficiency of such will of course depend on distance from the battery array.I wonder if the Tesla powerwall will be a feasible solution any time soon.

author: Zero999
author_rank: Super Contributor
timestamp: August 15, 2015, 12:20:57 pm
content: Is it really worth it from an economic perspective?How long will it take for you to see a return on your investment?What battery life do you expect?If the batteries need to be replaced before you've got the money you've spent on them back plus inflation, then it's not worth it and you would've been better off putting the money in the bank. Of course thse calculation isn't easy, since you don't know what the price of energy will be in the future.From an environmental perspective, you need to take into account the impact of the batteries being manufactured and recycled which is often not done in an environmentally friendly manner.

author: johansen
author_rank: Super Contributor
timestamp: August 15, 2015, 12:33:08 pm
content: as far as solar goes.. i can buy a pallet of solar panels for about 75 cents a watt.. i do have to pay for shipping however, which means i would need to buy 4 to 10 grand worth of panels before its really worth it.the problem being where i live, i would probably need 8 kw of panels to provide 8-16 kwh a day of electricity. not worth it at 10 cents a kilowatt hour.if the panels last 27 years, they would pay for themselves.in reality its probably worth it when i look at the electricity rates rising faster than inflation.lead acid batteries will cost you a minimum of 25 to 50 cents per kilowatt hour. --so you'd better have a good sized hot water heater, and a heat pump connected to a 500 gallon tank of water as a thermal buffer.the jury is out with regard to lithium iron phosphate being cheaper than lead acid.. it may very well be.as far as inverter cost goes.. its not negligible but its close to zero as far as efficiency goes.what is not zero is the no load cost. if your 6KW inverter sucks up 100 watts parasitic load thats probably unacceptable.there are ways to get it well below that.check the fieldlines.com forum for the recent thread on building your own inverter from relatively cheap power jack boards and winding your own toroidal transformer.

author: TheElectricChicken
author_rank: Frequent Contributor
timestamp: August 15, 2015, 12:45:35 pm
content: All solar is brilliant, just go for it. Start with one panel. Start saving right away. By the time you move along from one panel you'll learn a lot and be expert at big systems.You don't need batteries in the daytime. That is that part of your bill taking a hit. You can eventually set things up so that there are different tariffs on your own home grid. So that storage gets filled, lights get priority and off peak things like a stone polishing tumbler orhttp://articles.latimes.com/2011/mar/10/food/la-fo-grinding-grain-20110310get done later when there is too much sunlight.Don't worry about generators yet unless you have a factory near your house where they throw out wood. Then you can get one of theseorand also can drivebut it helps you when there is cloudy weather for a week or you want to have a welding party.

author: Simon
author_rank: Unknown
timestamp: August 15, 2015, 12:50:59 pm
content: Quote from: Hero999 on August 15, 2015, 12:20:57 pmEconomically I'm not sure. But I have a very strong desire to stick two fingers up to the government and the energy companies, whilst also being very well aware that prices are likely to rise. Let's face it just listen to the news, Centrica are making I believe 2000 people redundant despite doubling their profits over the last year the excuse is that they gave Joe public a 5% price reduction which was a partial passing on of their own wholesale costs going down. With this sort of attitude from our private and often foreign energy companies I'm willing to bet the money that energy prices will go up and they will come a time when they will start to go up quite quickly.As for battery lifetime I hear that well treated lead acid batteries can last 20 years. That is why I am only expecting 500 W capacity from a 110 amp battery and if I had 10 batteries that would be 5 kW. I believe the batteries are around £80 although I might get a good deal on 10. Of course the battery configuration is also driven by the inverters.Panels are cheap now it's actually a case of the fixings and wiring could be the thing that turns out to be more expensive than expected. I have a section of ground which would be ideal for a frame to hold a substantial amount panels of course the frame will cost money but my house roof does not point South so it's pretty pointless putting them up there.

author: TheElectricChicken
author_rank: Frequent Contributor
timestamp: August 15, 2015, 12:51:40 pm
content: Dont forget to remove the largest electrical loads that you have too. Like get solar hot water, because electric hot water sucks up the juice.

author: TheElectricChicken
author_rank: Frequent Contributor
timestamp: August 15, 2015, 12:58:03 pm
content: Quote from: Simon on August 15, 2015, 12:50:59 pmSimon,the best way to get cheap BIG batteriesis to work out where in your nearest city all the I.T. people are. That area is the best place to go door to door and ask about old Uninterruptible Power Supplies. Many I.T. firms don't even bother to change the batteries, they just throw out and buy new U.P.S.s every 12 months like clockwork because they are IT experts not battery experts and it's a negligible irrelevant cost on paper for big companies. Often places will just give them to you, but you can buy them at auction online for nothing. I usually set a limit of at least 2kva and less than $50. Yes you get the UPS as well as the batteries to test. End up with more batteries than you know what to do with. good ones too.

author: nowlan
author_rank: Frequent Contributor
timestamp: August 15, 2015, 01:34:00 pm
content: Going off grid will never be worth it, if you have access to the grid.Get solar, but size it to your day time needs. Even if your not home during the day, switch loads like washing to peak solar times.If you do want to pursue batteries, look at the what the EV guys are using.

author: ralphd
author_rank: Frequent Contributor
timestamp: August 15, 2015, 01:45:20 pm
content: In the last 5 years wholesale electricity rates have not gone up, they've gone down. The average in NA now is ~3c/kWh.http://iso-ne.com/

author: ralphd
author_rank: Frequent Contributor
timestamp: August 15, 2015, 01:54:39 pm
content: Grid-tie inverters cost ~30c/W, and are getting cheaper faster than the panels.https://www.littleboxchallenge.com/

author: Simon
author_rank: Unknown
timestamp: August 15, 2015, 02:15:57 pm
content: Quote from: ralphd on August 15, 2015, 01:45:20 pmwholesale yes

author: johansen
author_rank: Super Contributor
timestamp: August 15, 2015, 02:34:53 pm
content: Quote from: ralphd on August 15, 2015, 01:45:20 pmfor small residential houses, by the time you add the monthly minimum fee, you're past 20 cents per kilowatt hour.for these folks, solar is absolutely worth it, particularly in California where some folks are allegedly already paying 25 cents a kilowatt hour plus monthly fees.

author: Simon
author_rank: Unknown
timestamp: August 15, 2015, 03:27:35 pm
content: My heater is gas, I'd need the pure sine wave inverter for the electrics. Although considering it has a mains powered mechanical timer clock and it has its own wiring back to the main switchboard I might as well leave it connected to the mains.

author: TheElectricChicken
author_rank: Frequent Contributor
timestamp: August 15, 2015, 03:42:10 pm
content: Quote from: Simon on August 15, 2015, 03:27:35 pmCan't change the mechanical clock for you, but I do know that the output from UPS inverters is much better than the mains.

author: ralphd
author_rank: Frequent Contributor
timestamp: August 15, 2015, 04:35:21 pm
content: Quote from: johansen on August 15, 2015, 02:34:53 pmEven 25c/kWh is cheaper than what it'll cost to go off-grid. For grid-tie, the economies of scale kick in around 8-10kW, but your average residential suburban home in CA doesn't have enough south-ish facing roof for 8-10kW.

author: johansen
author_rank: Super Contributor
timestamp: August 15, 2015, 06:22:43 pm
content: Quote from: ralphd on August 15, 2015, 04:35:21 pmperhaps, but if my folks were paying 25 cents/kwh i would buy solar panels where i live now, i think i could pull it off.payback should be in 8 years if you're off grid completely.that said most people can't. and the reason why is because the only thing they know is:professional installation: 1 dollar per watt.grid tie inverter: 1 dollar per watt.letting the utility buy your own power for less than half the residential rate? priceless.but once you add up all the inscentives and government cash, yes it is very profitable if you can sell the utility power at 46 cents a kilowatt hour.the key thing to do is shift all your power to onpeak hours.cook food with gas, heat your hot water with a heat pump during peak hours. (yes this does work and a few people have built their own systems using just regular propane as a heat fluid, you don't need no titanium turbines and co2)put your washing machine on a timer to wash your cloths while you're at work, etc, etc.once you do all these things and half a dozen others your battery load is minimal.. and then you can afford to experiment with lipho4 cells which should be cheaper than lead acid on a lifecycle basis (but no one has proved it yet)

author: Simon
author_rank: Unknown
timestamp: August 16, 2015, 11:00:55 am
content: Seems the highest input voltage you can get for an non grid tie inverter is 48V, and they are not bad either on ebay although I'm wary, 100 quid can get you a KW

author: Aodhan145
author_rank: Frequent Contributor
timestamp: August 16, 2015, 01:13:29 pm
content: If you think of going on-grid. (Battery technology today is not good enough yet. This might be your best option) You can get a Sunny Home Manager for a SMA Inverter. It can turn off and on loads in your house. So when you are generating enough electricity you can use it for things like your washing machine, heat pump,. This will get the most money out of the electricity you generate instead of selling most of it back out to the grid. The only problem is the Sunny Home Manager does not have UK sockets/plugs. So you need a Plugwise Stretch with its socket, it communicates with the Home Manager and the Home Manager communicates with the inverter. The Plugwise Stretch also has a feature to turn off appliances when they have been on standby for a long time.

author: Simon
author_rank: Unknown
timestamp: August 16, 2015, 01:29:42 pm
content: Quote from: Aodhan145 on August 16, 2015, 01:13:29 pmThe problem is I have one of those inconvenient things called a job. So I would not be at home to use electricity during most of the time it is been made available. It is very clear to me between government policy and the attitude of the energy companies that I would never be able to sell electricity back for any money. And in case it was not obvious from my initial post this is not so much about saving on my electricity but sticking two fingers up to the government and the energy companies. In time my investment may well pay off particularly if the cost of energy does go up.

author: KD0CAC John
author_rank: Frequent Contributor
timestamp: August 16, 2015, 02:04:51 pm
content: How come nobody looks at return on money with just paying your electric bill monthly ?The only issue I see is the upfront cost of building a system for hole house .In the US there are a lot of companies installing a system and you pay them , this is for profit , so the idea that it does not pay for its self is off .I have been doing solar for decades and watched prices for panels fall from as high as b.s. / rip off $25 per watt , and now as low as $00.26 per watt .As for inverter prices falling , that only seems to be happening with non home use portable cheep inverters .Good inverters for hole home use are still high .As for batteries , buying right , flooded lead acid is still the cost per- performance , especially if you find surplus commercial , fork lift , telecom etc.My last battery bank was 4 x Trojan 6v L16 and lasted 12+ yrs. before I moved did use and froze one winter .Nickel Iron batteries can last 50 + yrs. and almost hard to kill .

author: TheElectricChicken
author_rank: Frequent Contributor
timestamp: August 16, 2015, 02:09:02 pm
content: Quote from: Simon on August 16, 2015, 11:00:55 amI'm not sure anyone would want one, however there are UPS's which use battery strings of 90v or so. I have one, I can find out exactly the number of 12v batteries that it has in series if anyone has an interest (actually is it 10?)Making a home made charger for that string of batteries wouldn't be too hard. I have not tried as I do not like high voltage DC myself. Some people can deal with it though and have probably done it.

author: Aodhan145
author_rank: Frequent Contributor
timestamp: August 16, 2015, 02:18:41 pm
content: Quote from: Simon on August 16, 2015, 01:29:42 pmIt works for when you are at work. You can throw your dirty clothes in a washing machine, then when you are at work it washes the clothes or if you use a heat pump / immersion heater you can store the hot water in a tank for when you are back from work. There is lots of other applications of this. Nobody is really at their house when they are generating the most electricity (most people have those things called jobs).

author: ralphd
author_rank: Frequent Contributor
timestamp: August 16, 2015, 02:19:11 pm
content: Quote from: KD0CAC John on August 16, 2015, 02:04:51 pmCAD $1700 == USD $1300 for a 6kW inverter is 22c/W:http://dnmsolar.com/product.php?product=126

author: TheElectricChicken
author_rank: Frequent Contributor
timestamp: August 16, 2015, 02:30:28 pm
content: Quote from: ralphd on August 16, 2015, 02:19:11 pmStrange, smaller ones are much cheaper$120 1.5kwhttp://www.ebay.com.au/itm/1-5-kW-Solar-Grid-Inverter-Brand-New-in-Sealed-Box-/141743406192$100 1.5kwhttp://www.ebay.com.au/itm/Sunna-1500TL-1-5-kw-Grid-Tie-Connected-Solar-Inverter-/221847655429$200 2kwhttp://www.ebay.com.au/itm/Sunnyroo-SR2000TL-2-kw-Grid-Tie-Connected-Solar-Inverter-/321820768035they are for 220v though...

author: Simon
author_rank: Unknown
timestamp: August 16, 2015, 02:40:35 pm
content: smaller inverters will be cheaper, high power design in a pain in the ass, it's not just a case of using more powerful components

author: TheElectricChicken
author_rank: Frequent Contributor
timestamp: August 16, 2015, 02:46:52 pm
content: Quote from: Simon on August 16, 2015, 02:40:35 pmIndeed. It looks to me though, that using 3x 2kw units brings the price to $600 rather than 6kw @$1300, which begs the question why use a single unit, have redundancy. There is something I'm missing.

author: Simon
author_rank: Unknown
timestamp: August 16, 2015, 02:53:47 pm
content: the large units will be properly designed, that is also a grid tie inverter you linked too and they cost more. The bigger the unit the more goes into the design and usually the higher the quality.I will be going off grid so standard pure sinewave inverters will be fine. I have 4 circuits in my house so I can and will be splitting them down into different inveters. My lights now all LED only need 100W my sockets don't usually need to be supplying more than 3KW so a 5KW unit per floor will be fine, the only problem I see is running the 1KW microwave and 3 KW kettle together.

author: TheElectricChicken
author_rank: Frequent Contributor
timestamp: August 16, 2015, 03:46:17 pm
content: I guess it is the same thing with lumber, people think of the longest piece that they'll need then buy only that length for all the lumber, bring it home and proceed to cut it all into smaller lengths. It's that kind of premium.They just add up to the total and get that number of kilowatts for the whole house.I like redundancy. I'd rather blow a cheap inverter up and then have 4kw to cook dinner and google another one with the lights on than wonder what to do in the dark when 6kw fails.But I not buy inverter, UPS secondhand for $50 has that covered. I think of getting the solar controllers and such.I also want to make solar storage cooker with barrel of salt or stone that stays hot 24/7 for cooking for free.

author: ralphd
author_rank: Frequent Contributor
timestamp: August 16, 2015, 09:28:18 pm
content: Quote from: TheElectricChicken on August 16, 2015, 02:46:52 pmI think you didn't look at the details. "Warehouse clearout" and "1 month warranty".Could well be out of spec units that failed testing...

author: splin
author_rank: Frequent Contributor
timestamp: August 17, 2015, 01:16:41 am
content: Going off grid using solar PV alone isn't easy in the UK - we don't get a lot of sun in the winter so you need a lot of panels and big batteries and even then you'll almost certainly need a generator to get you through the darkest parts of the winter.There is an excellent tool to help you determine suitable panel and battery sizes based on historical solar insolation data:http://re.jrc.ec.europa.eu/pvgis/Select your location on one of the maps and then select the 'Stand-alone PV' tab. As an example, I tried a London location and created the attached spreadsheet which works out the lowest solar panel + battery cost for three scenarios:a) The batteries never completely emptyb) The batteries become fully discharged on 2.5% of days annuallyc) The batteries become fully discharged on 3.5% of days annuallyI selected module inclination of 70 degrees to maximize production in winter when you most need it, 1000W solar panel and increased the battery size until the results showed the battery just became empty on 0%, 2% (ie. 2.5%) and 3% (i.e 3.5%) days respectively.Selecting a battery cutoff limit of 0% (fully discharged) should be OK because the deep discharge batteries you'd need can be 100% discharged, if not recommended, and would only be fully discharged on a few days a year at most. In reality you would need to use the generator on those days anyway.I've also attached a spreadsheet of prices of various lead-acid batteries in Europe which calculates the lifetime cost per kWh. I created it a while ago but the prices seem to still be unchanged. You might be able to buy cheaper traction batteries for fork-lift trucks but they don't often have online price lists. You can also buy second-hand fork lift batteries which don't have enough capacity left for a full shift at a warehouse but may be fine for your use. A risk, but OK if they are cheap enough. Buy the old forklift at the same and you solve the problem of moving tonnes of batteries around your property!The typical UK daily consumption of 10kWh would require at least 41kWh of batteries and 12 kW of panels costing at least £10k (the shipping cost for the batteries is not included in the spreadsheet). On top of that the ground mountings (you could use wood), wiring, charge controller, DC isolators (not cheap), fuses, meters, a shelter/building for the battery and generator, temperature monitor(s), generator(s), fuel storage etc. would be required. Reducing your consumption will help considerably providing you can convince your partner not to use the tumble drier and not to keep leaving the garage light on.Don't forget to include de-ionized water in the running costs as large flooded cell batteries use a lot of water, although one off-gridder at least, uses winter collected (ie. dust free) rain water apparently without harm.It can be done if you have space (and planning permission) for enough panels. But don't forget batteries must not be neglected or they can be easily destroyed, although the flooded cells in the spreadsheet are much more robust than the maintenance free AGM etc. lead-acid types. They need to be equalized periodically with an equalizing charge to de-stratify the electrolyte and prevent sulphation and electrolyte levels and gravity need to be checked regularly.Early deaths of batteries due to lack of experience or neglect isn't uncommon and can blow the financial case. It's not uncommon for batteries to fail early for no obvious reason so you still take a risk. If the cells aren't well matched, weaker cells will suffer as they will suffer deeper discharges and more overcharging than the others causing a gradually accelerating decline. One off-gridder had to fight a supplier to get a pack replaced - she had to prove to them, using her chemical engineering experience, that the manufacturer had changed the separator material and she'd ended up with cells from different batches which performed differently.And then you have the problem of deciding to replace the whole pack or just the failed cells which isn't a great idea.And to achieve the < £.07/kWh lifetime battery cost the battery will need to be operating for 20 years or more (because to operate on PV alone the battery is necessarily very large and so has very shallow discharges for the majority of the year). Are you sure you'll still be living in the same house in 20 to 25 years - no buyer is likely to want to take on such a system? Will you still want to be managing the batteries and maintaining the generators in 25 years? Or would your partner want to take it on should the batteries outlive you?Don't forget the hazards - some recommend having a barrel full of water nearby to jump in when a cell explodes for reasons unknown, or due to dropping a spanner across the terminals and showers you with acid - not unknown.If you fancy the challenge then go for it - it could be a lot of fun and might even save money especially if you can get cheap or free second hand batteries; just don't underestimate the work and risks involved. I'd suggest organizing the cells into at least 2 parallel batteries if possible so that when you have a problem with one of them you aren't faced with running the generator for long periods until you can get replacements. Alternatively you could have a smaller reserve battery made from retired UPSs or older cells with insufficient capacity for your main bank.You'll have a large surplus of electricity during the summer so try to devise a profitable use - a bit of aluminium smelting perhaps? Oh and the batteries will have useful scrap value when they do need to be replaced - if they haven't been nicked, along with your panels when you were on holiday. (Ground mounts are more vulnerable than roof mounted panels).A good UK resource is the Navitron forums which has some experienced off-gridders:http://www.navitron.org.uk/forum/

author: bills
author_rank: Frequent Contributor
timestamp: August 17, 2015, 03:41:06 am
content: SplinGreat write up very concise, 35yr's ago I owned a l/a battery manufacturing shop.I agree with you on the care and feeding of l/a batteries to get the most life from these you want to choose batteries with the thickest plates. Automotive, sla,(agm) just don't cut it,At minimum a good quality golf cart battery.

author: johansen
author_rank: Super Contributor
timestamp: August 17, 2015, 04:04:47 am
content: Quote from: splin on August 17, 2015, 01:16:41 ami agree with the last part, you have to use the batteries till they have fallen to less than 50% nameplate capacity.but.. if you actually believe you can get 2100 cycles to 80% dod, then i don't know what to tell you. 500 cycles to 80% dod would be good.. that's why i said 25 to 50 cents/kwh.now if you only discharge to 20% dod then you should do a lot better, if the battery can handle twice the total energy flow then you would have 500 times 8 or 4000 charge discharge cycles to 20% dod.Or 8000 to 10% dod.10% dod is what a lot of off grid folks try to reach... 8000 days is 22 years.

author: bills
author_rank: Frequent Contributor
timestamp: August 17, 2015, 04:54:07 am
content: I think one of the main factors in battery life is the battery (duh) a lot off grid users are using batteries that are not suitable for the application, as I posted in my last post you need a battery that has plates that are thick enough to withstand heavy use, and that results in a lower amp hr. capacity. But longer life.I worked on a system for southern cal. edison about 25 years ago for off peak storage they had a 56,000 sq foot building with banks of 2volt cells that were 18"x18"x30"(8000) the cells were in glass jars and were 11 plates (IIRC) the plates were about .750" for the positive and .600 for the negative they used compressed air to circulate the electrolyte. (think aquarium filter)I was talking to one of the project engineers and they expected battery life to be 30 years.Only they were having a problem with heat, Well who ever designed the cells used Styrofoam shims to take up the space in the jars appox. .750 one each side and to add to that they used Styrofoam to separate the jars (earthquake protection) I also noticed the air tubes extended into the sediment chambers at the bottom of the cellscausing any of the material to be circulated back into the active material.I pointed this out to the project engineer and was given the look (who the f--k are you)last I heard the project was a failure.BTW my part in this project was installing and maintaining the air system I worked for Ingersol rand at the time.linkhttps://www.edison.com/content/dam/eix/documents/innovation/smart-grids/Energy-Storage-Concept-to-Reality-Edison.pdf

author: TheElectricChicken
author_rank: Frequent Contributor
timestamp: August 17, 2015, 05:37:55 am
content: Quote from: ralphd on August 16, 2015, 09:28:18 pmYou can buy twice as many and STILL save money. If they fail, the credit card or paypal or the seller give back the money. If they work for a week then they are perfectly normal, as good as any other item. There is no saving in making something that lasts a week as opposed to years, such things are hard to engineer. Some companies manage it.There are no end to companies that have permanent "Warehouse clearout"s and 1 month warranty is just fine. It works for a month it's likely to keep on working. You pay for your own fixing if ever it needs it. As you have 3 extra swap units because you got 6 instead of 1 and still saved money that's fine.

author: bills
author_rank: Frequent Contributor
timestamp: August 17, 2015, 05:53:05 am
content: BTW I have a grid tied system 3kw. and my cost per year is about $ 300.00 a year, cost for the installation was $ 15,000.00 but that was 10 years ago.It has paid for it self ,my power bill was $250.00 to $ 350.00 usd per month for the summer (4 months) and $ 60.00 to $ 70.00 for the rest of the year. now my monthly bill is $2.00 to $4.50 than I get an adjusted bill every September for $250.00 to $300.00 for the year. and the system works ( but not as it was sold to me ) This is an another story.I have no problem with a grid tied system they work (at least in the usa)

author: bills
author_rank: Frequent Contributor
timestamp: August 17, 2015, 06:03:22 am
content: Mr. chicken what are you trying to say?sure we can salvage a but load of UPS's but how long is that going to work? than what are you going to do with the old stuff?Sir you are entertaining but not very relevant.I will have to admit it is fun to read your posts.

author: Simon
author_rank: Unknown
timestamp: August 17, 2015, 06:07:36 am
content: My intention is not to be completely off grid at least not immediately as this is something that would be very expensive. However I do not want to do grid tie inverter's as this is where I risk giving the electricity back to the electric company for free.There are lots of leisure batteries Claiming that they can be discharged 500 or 700 times to a discharged state. That is why I would not want to discharge any batteries beyond 50% because I don't see the point in using those valuable cycles and destroying the batteries early.Having established that 48 V is the high input voltage I can get for an inverter I would obviously be running set of 4x 12 V batteries in series which is not too expensive to buy at a time and I can add more sets in parallel.Obviously the other possibility is to switch to an economy seven tariff and charge the batteries up overnight if solar has not done enough this is what photonic induction does in fact.So my next main problem is to work out what batteries to buy. I don't need anything huge I was thinking around the 110 A mark there are plenty of cheap leisure batteries but are they good enough? I don't exactly want pounds any battery I buy I will just gradually add batteries to the system to make it capable enough.

author: TheElectricChicken
author_rank: Frequent Contributor
timestamp: August 17, 2015, 06:14:25 am
content: I doubt any educated person would name anything 'edison' if they wanted it taken seriously.

author: bills
author_rank: Frequent Contributor
timestamp: August 17, 2015, 06:25:57 am
content: SimonI don't know what the rules are in the UK. ( I will have to reread to this thread to understand)here in the us the power co's are required to buy the power in excess that you use.the price is nowhere near what they charge you for the top tier rate it is close to the lower tier rate.If anyone is confused about tier rate let me know and I will try to explain.

author: bills
author_rank: Frequent Contributor
timestamp: August 17, 2015, 06:28:28 am
content: Quote from: TheElectricChicken on August 17, 2015, 06:14:25 amSnappy come back.regardsbill

author: bills
author_rank: Frequent Contributor
timestamp: August 17, 2015, 06:33:05 am
content: Wow note to self don't relay on spell check.( RELAY )

author: TheElectricChicken
author_rank: Frequent Contributor
timestamp: August 17, 2015, 06:35:51 am
content: Quote from: bills on August 17, 2015, 06:28:28 amI'm not trying to be snappy or have any argument or anything, I'm just wondering why any educated person would want to associate themselves with a loser who electrocuted kittens, puppies, topsy the elephant, a prisoner, and so on. He stole everything, never invented a thing, his teacher described him as "addled" which describes a chicken egg in which a developing chick has died. Tesla, I can understand why you'd name a car or a company Tesla, but Edison ? It says that these people take you for idiots.

author: bills
author_rank: Frequent Contributor
timestamp: August 17, 2015, 06:52:00 am
content: Mr. ChickenEdison was an unusual guy.Gee do you watch movies listen to music how about multiplex, yes he was a different person but a genus. ( GD spell check)Would you like more info on Edison please let me know .regardsbill

author: notsob
author_rank: Frequent Contributor
timestamp: August 17, 2015, 07:14:18 am
content: Have a look at the lith-ion storage packs that elon musk [based on the ones he has in Tesla's] is intending to sell for home energy storage

author: Aodhan145
author_rank: Frequent Contributor
timestamp: August 17, 2015, 03:04:35 pm
content: Quote from: notsob on August 17, 2015, 07:14:18 amThose Powerwall's are quite impressive. 10kwh for $3,500 if I remember correctly.

author: Simon
author_rank: Unknown
timestamp: August 17, 2015, 04:46:31 pm
content: Quote from: Aodhan145 on August 17, 2015, 03:04:35 pmFor £1200 I can get the same power in lead acid allowing for 50% only discharge....

author: bookaboo
author_rank: Frequent Contributor
timestamp: August 17, 2015, 04:52:06 pm
content: Quote from: Simon on August 17, 2015, 04:46:31 pmDoesn't the powerwall do all the solar charging and include an inverter?In any case, I wonder if you would get a better return direct hot water solar. Straight to a buffer tank so you can give the fingers to British Gas, you wouldn't be able to do much of the project yourself but anyone I know that has them reckons they are a great investment.

author: Simon
author_rank: Unknown
timestamp: August 17, 2015, 05:06:18 pm
content: I live alone so think i might use more electric than gas for hot water that in winter won't help much. The best location is too far from the house for the pipe work to work out.

author: AG6QR
author_rank: Frequent Contributor
timestamp: August 18, 2015, 05:45:30 am
content: Quote from: bookaboo on August 17, 2015, 04:52:06 pmNot at that $3500 price -- that's just the battery alone.http://www.autoblog.com/2015/05/21/what-do-you-really-get-for-7000-tesla-powerwall-home-battery/Lithium has a tremendous weight advantage, so I understand why it's ideal for use in electric vehicles. But weight isn't nearly so important for stationary in-home applications. Lead acid isn't sexy, but it's boring, dependable, and cheap. And it has an established infrastructure for recycling. It seems well suited to the job.Gotta admit, the packaging of the powerwall is pretty, sleek, and curvy, though.

author: DenzilPenberthy
author_rank: Frequent Contributor
timestamp: August 18, 2015, 10:39:37 am
content: Have a good look through the website of 'Wind and Sun'. They've done tonnes of off-grid installations from houses up to large islands etc. They also are importers and distributors for loads of the good quality manufacturers of panes/inverters/batteries etc.I recently did a fully off grid set up for some friends using all stuff from Wind and Sun. REC panels, Trojan flooded batteries and Victron inverter, battery charger and battery monitor. Extremely happy with all of it.For a domestic set-up Victron do all-in-one units which combine MPPT charge controller, Inverter and batteries in one unit. Plus mains and generator AC inputs and switching. Just add panels and a G59 relay to changeover to the grid supply and you're all set to go.http://www.windandsun.co.uk/products/Inverters/Victron-Inverters/Victron-InverterChargers#.VdMJ1PlVhHw

author: DenzilPenberthy
author_rank: Frequent Contributor
timestamp: August 18, 2015, 10:46:47 am
content: I should add to that - If you are doing a homebrew system then don't overlook the fact that there are some quite specific requirements for changeover switching between private and public supply and how to manage the earthing of the two systems - see BS7671 for details on that.Also if you are using several smaller inverters feeding separate circuits then it will be a ball-ache to organise appropriate switching to interlock them from each other and the public supply. Also if they are not able to be synchronised together then bear in mind that you could have circuits which are 180deg out of phase with each other which would leave you with perhaps 480v RMS phase-phase inside a single-phase domestic wiring system which isn't designed to cope with that. (679v peak!)Aaaaand... it is likely that small cheap inverters will not have sufficient power capacity to supply sufficient fault current to blow fuses or operate circuit breakers within the required times in BS7671aaand.. probably more cans of worms I haven't thought of yet

author: TheElectricChicken
author_rank: Frequent Contributor
timestamp: August 18, 2015, 11:02:52 am
content: Quote from: DenzilPenberthy on August 18, 2015, 10:46:47 amthis is nonsense if all wires are connected to the mains.

author: DenzilPenberthy
author_rank: Frequent Contributor
timestamp: August 18, 2015, 11:10:26 am
content: Quote from: TheElectricChicken on August 18, 2015, 11:02:52 amDid you miss this bit?Quote

author: Aodhan145
author_rank: Frequent Contributor
timestamp: August 18, 2015, 11:36:06 am
content: Quote from: AG6QR on August 18, 2015, 05:45:30 amWe were talking about just the batteries. Look at the number charging cycles lithium iron phosphate has compared to Lead Acid. Lead Acid are shit. If you want to stick with Lead, Lead Crystal looks better. LFP batteries have massive life cycles.

author: Simon
author_rank: Unknown
timestamp: August 18, 2015, 11:50:20 am
content: is the victron inverter grid tied ? quite expensive though but guess it's well build. I was aiming to build my capacity gradually. 1 set of batteries, inverters for just lights and add some panels (My current capacity is just 40W/hour so need to get some decent size panels)

author: Seekonk
author_rank: Super Contributor
timestamp: August 18, 2015, 12:15:59 pm
content: Read very few of the posts, but most are into big dumb power. Any time you use batteries, the cost per KWH used is about 12 cents. With that you can't win economically. Add to that, most systems are over designed so they can operate without a bit of thought. Most of the potential energy that can be harvested is wasted. Making a system smart and scheduling loads will be the next generation of RE.I live off grid in the summer for many months and use only a car battery out of a vehicle I don't bring with me. It is used primarily for initial surge current of the fridge inverter. Storage is not necessary to the massive extent most moronic solar systems are designed to. Fridge runs real time off solar only during the day, I store cold for night. Any excess power is converted to hot water at power point. Currently I divert over 3KWH a day to heat water, more than enough for my uses. It is possible to operate appliances real time without storing energy if done one at a time under processor control. I have next to nothing invested in all the electronics.

author: DenzilPenberthy
author_rank: Frequent Contributor
timestamp: August 18, 2015, 12:16:13 pm
content: No,it's not grid tied, just a standard inverter. The AC inputs allow battery charging (and AC feedthrough) when running off a generator or plugged into mains AC.http://www.windandsun.co.uk/media/314351/Victron-EasySolar-1600-Data-Sheet.pdfIf it's like the other Victron stuff I've used then yes it definitely feels like you're getting your money's worth quality-wise. In fact the battery charger I used for my friends' system got replaced FOC recently by Victron as they were recalling some units due to not getting expected performance out of some components (read: probably a dodgy batch of electrolytics, right?). That makes me think that they actually care about their units' longevity and quality. I've not seen any recalls for cheap chinese inverters on ebayThe system I built used all separate components but it required a lot of thinking and design work and a significant amount of time wiring up. If I was doing the whole project again I think I'd definitely use the all-in-one unit. You can add battery and panel capacity incrementally as your requirements grow but it's probably worth generously over speccing the components like charge controller and inverter. It will cost a relatively small amount extra now but will avoid having for example to bin a £300 inverter and buy a £400 one if you want an extra 500VA in the future. e.g. in the system I built It was an extra £30 something pounds to over spec the charge controller so that in the future I could double the number of panels and batteries if necessary.

author: TheElectricChicken
author_rank: Frequent Contributor
timestamp: August 18, 2015, 01:32:39 pm
content: Quote from: DenzilPenberthy on August 18, 2015, 11:10:26 amHow can you have all wires connected to the mains in a single phase system and still be out of phase ? hello ? how. You have to find an idiot on the scale of you forget your multimeter and so test for 220vAC by touching your tongue to the mains switchboard. really. Draw up a circuit with one phase wiring and show what you mean. You can only do it with a multiphase wiring system at the least,

author: DenzilPenberthy
author_rank: Frequent Contributor
timestamp: August 18, 2015, 02:10:35 pm
content: If you take the time to read Simon's post and my reply he was suggesting feeding separate circuits in his house with separate inverters.It then becomes several different single phase installations but with no way of ensuring they are all in phase with each other. Imagine the following situation: you are feeding, for example, the upstairs lights from inverter A and the downstairs lights from inverter B. The inverters are not synchronised together so it is entirely possible that the supplies to the upstairs and downstairs lights are 180deg out of phase.Now think about the double switch at the bottom of the stairs where Switch 1 controls the stairway lights fed from upstairs and switch 2 controls the hall light which is fed from downstairs. The wires that perhaps share a conduit run and the double switch now contain wires with 480v between them which they are unlikely to be rated for.

author: TheElectricChicken
author_rank: Frequent Contributor
timestamp: August 18, 2015, 02:21:05 pm
content: Quote from: DenzilPenberthy on August 18, 2015, 02:10:35 pmyes, sorry, here it is.Quote from: Simon on August 16, 2015, 02:53:47 pmI get a similar worry when I disconnect the 'lights' circuit at the fusebox to convert it all to 12v for solar installations. It's like, did they do something bodgey ?

author: SeanB
author_rank: Super Contributor
timestamp: August 18, 2015, 05:23:02 pm
content: Most mains rated wire is tested to 1kV in any case, as it is the same wire type used for 4 phase circuits in any case. Thus not a worry about voltage, more the accidental connecting of the outputs of different inverters together. The outputs must be separate, both line and neutral wiring, or else you will have issues.

author: Simon
author_rank: Unknown
timestamp: August 18, 2015, 05:28:17 pm
content: I've seen automotive rated wire that officially only goes to 50V used at 300V, although I did my nut when I found out, but it worked in that instance.

author: johansen
author_rank: Super Contributor
timestamp: August 18, 2015, 05:36:53 pm
content: Quote from: DenzilPenberthy on August 18, 2015, 02:10:35 pmromax on their website says 300 volts, but when you use romax, you don't have loose wire floating in conduit, so you won't have that problem.also, the wire sold in europe where 240 is the standard minimum will be rated to 600 volts minimum.additionally, the THHN wire used in conduit in the states is rated 600 volts.two unsynchronized 240v inverters is not a problem for a household installation unless you don't know what you're doing or the house is wired wrong. additionally most legit inverters which have a groundable output.. also allow for synchronization.the inverters which cannot synchronize usually have floating outputs.. or their output midpoint is connected the battery negative terminal.. this latter issue can be a mess to work with.

author: Simon
author_rank: Unknown
timestamp: August 18, 2015, 05:40:26 pm
content: Actually the cable rating is not a problem anyway in the event of inverters being 180° out of phase. Each conductor is already rated to withstand the full peak voltage in either positive or negative with respect to ground. If two wires have current in them which is 180° out of phase it would make no difference at all as there would be twice the amount of insulation between them. The cables have to withstand a single voltage anyway so that you can handle them without getting a shock to earth. The problem never existed.

author: splin
author_rank: Frequent Contributor
timestamp: August 19, 2015, 01:12:34 am
content: Quote from: Simon on August 17, 2015, 06:07:36 amQuoteSimon, I think you will be seriously dissapointed if you buy 110A leisure batteries for £80 hoping to get 500+ 50% cycles. I think you should be happy if you get 200 cycles but 100 might be more likely. Take a look at this:http://www.caravanclub.co.uk/media/6552072/technical.pdfAnd these shocking tests:http://www.caravanclub.co.uk/media/13871919/ccmnovtechnical.pdf?type=archiveThe 115Ah Trojan 27TMH is £113.5 and claims 600 50% cycles, but the golf cart batteries, and others in the same class, should be better - the T105 is 6V, 225Ah so the same capacity for £119 but claims 1200 cycles, so potentially much better value. I'd be very surprised if you could get anywhere near 1200 cycles though.A Crown 27DC115 115Ah cost £117 from BimbleSolar and claims 525 cycles @ 50%.http://www.yhipower.co.nz/downloadhandler.axd?type=2&id=100096&ins=1Don't know how good they are but the cycle life table looks very suspect showing 300 x 100% DOD equivalent cycles at 20% and 40% DOD, reducing to 262.5 @ 50% DOD then increasing to 350 @100%! You have to wonder if they they just make the numbers up sometimes...Note: none of the above are recommendations - just examples for comparison.As to the 20 year lifetime, you might achieve that on the top of the line batteries but T105s are typically expected to last 2-7 years. You might get lucky and get 8+ years but you might only get 4 or 5, no matter how well you treat them.Many suggest starting with cheaper batteries as you are likely to kill them while you gain experience.

author: Simon
author_rank: Unknown
timestamp: August 19, 2015, 06:10:59 am
content: I'm confused. The listings generally refer to full discharge cycles and that the batteries can take five or 700. Now what you are saying is that these discharge cycles are only to 50%. I thought the whole idea of only discharging to 50% was to never enter that region of discharge that permanently damages the battery and reduces its lifespan. At this point I might as well get car batteries.

author: bookaboo
author_rank: Frequent Contributor
timestamp: August 19, 2015, 08:36:12 am
content: Some useful info on LA battery choice:http://sterling-power.eu/support-faq-2.htm

author: Aodhan145
author_rank: Frequent Contributor
timestamp: August 19, 2015, 09:38:01 am
content: You should watch mjlorton's videos if you haven't yet.

author: DenzilPenberthy
author_rank: Frequent Contributor
timestamp: August 19, 2015, 09:39:29 am
content: Quote from: Simon on August 18, 2015, 05:40:26 pmThis problem was discussed some time ago on the IET forum (I think). It really does open a big can of worms. There was someone who was wanting to install some stuff on a farm which had a split-phase supply. i.e. two phases 180 deg apart instead of the more usual 120deg. It's really unusual here.Aside from the insulation of the wiring which yes, will be fine at 480v (if it's all rated at 600/1000v) - your circuits will still need protection from overcurrent. The problem is that you will find it extremely difficult to find a consumer unit or any accessories which are rated to 480v phase-phase. Three phase boards commonly available here are typically not rated to such a high phase-phase voltage. You could use a separate 1 or 2 way consumer unit for each inverter but then you'll need a lot of wall space to fit one for each inverter plus another one for your incoming mains plus all the contactors or changeover switches plus the inverters themselves. You will find that you have a very significant problem on your hands when you show all of this to your house insurance company if it is not all done and signed off by someone who knows BS7671 inside-out and back-to-front. You will likely then also have a big problem with your mortgage company when you can't get house insurance. Also bear in mind that if you do a homebrew project of this nature that isn't fully compliant with the regs then when you come to sell your house the purchaser would be wise to include the cost of a full rewire in their negotiations.I fully agree with several commenters above that yes it will work but my point is that if you wan't to do this project properly then there are significant issues with using multiple inverters which are certain to end up costing more than using one large inverter.I'm not purposefully trying to pee on your fire but I'm just pointing out some issues that might not be obvious at first glance.

author: DenzilPenberthy
author_rank: Frequent Contributor
timestamp: August 19, 2015, 10:24:19 am
content: Also to open some more cans of worms, your inverters will likely have a floating output (if you use small cheap ones). This will mean some of your circuits will be supplied from an IT system (not a good idea). You will have to modify them yourself to reference the output to earth. Expensive or large inverters will be designed with this in mind and have an internal N-E link which can be fitted. If the rest of your house is supplied from a TNS or TNCS system then you will have to convert it to TT because you can't rely on the electricity company's earth when using your own power. This will mean earth rods, extra cables and an RCD on your mains incomer. Remember to add suitable double pole switching so that your inverters' N-E links aren't there when you switch over to the public supply.Also you will have some work to do to check that your circuits will still disconnect in the required time when supplied from your inverters. It is likely that they won't because they can't supply enough current. This will mean all kinds of RCDs everywhere and maybe upgrading the bonding conductors throught your house.cans of worms everywhere!! Sorry!

author: Simon
author_rank: Unknown
timestamp: August 19, 2015, 11:50:34 am
content: Quote from: bookaboo on August 19, 2015, 08:36:12 amSo basically I need forklift batteries

author: bookaboo
author_rank: Frequent Contributor
timestamp: August 19, 2015, 12:59:54 pm
content: Well basically yes some form of deep discharge battery, there may be other newer options since that article was written but it outlines the basic difference between car batteries and power back up batteries.

author: DenzilPenberthy
author_rank: Frequent Contributor
timestamp: August 19, 2015, 01:05:33 pm
content: Yep. Flooded lead acid batteries are king for this sort of application. It does mean though that they'll need to be maintained with de-ionised water occasionally and you'll have to put some thought into how to safely manage the explosive hydrogen and oxygen they will give off while charging.I've used these before. Very happy with them.http://www.trojanbattery.com/product/t-105-re/Edit: these are part of a range of suitable renewable energy batterieshttp://www.trojanbattery.com/markets/renewable-energy-re/and they have a very handy calculator to work out the required battery bank size based on your loads and how discharged you want the batteries to get. The datasheet for the battery will have a graph of depth-of-discharge vs how many cycles they will last.http://www.batterysizingcalculator.com/

author: max_torque
author_rank: Super Contributor
timestamp: August 19, 2015, 02:37:36 pm
content: Sorry to say, but i can think of very many better ways to "stick it to da guverment" than this!!Going off grid in the UK is totally pointless waste of money! Take the same capital, put it in a suitable ISA (tax free) your pension (taxfree) or invest abroad( could be tax free if you have a good accountant.....), or best, use it as a deposit on a BTL property!Then wait 10 years, retire early, and emigrate to a nice hot country with good beaches and a favourable view on rich british ex-pats.......... ;-)Take THAT you pesky Parliamentarians!

author: TheElectricChicken
author_rank: Frequent Contributor
timestamp: August 19, 2015, 03:41:35 pm
content: Quote from: max_torque on August 19, 2015, 02:37:36 pmNow that IS insane, you can't taper a ponzi scheme and the UK is almost maxed out on it's bubble economy. Speaking of Maxed out, Max Keiser is a brilliant source of information that anyone can understand about this. The LAST thing any sane person would want to do right now is put money into the market. Solar panels ON your roof can't crash all at once the way the stock market can. Well, perhaps a few extra bolts.... as for the markets, you CANNOT taper a ponzi scheme. Can't be done.edit: add searchwww.google.com.au/search?output=search&q=taper+ponzi

author: splin
author_rank: Frequent Contributor
timestamp: August 19, 2015, 03:45:12 pm
content: Quote from: Simon on August 19, 2015, 06:10:59 amIf a cycle life is quoted at all for cheap leisure batteries they rarely provide any details, but where they do 50% DOD is typical. Even then they never detail the test conditions - what rate of discharge? How long before the batteries are recharged? How long a rest before the next cycle? Temperatures? You can be certain your operating conditions won't match the ideal conditions used for their quoted cycle life hence you will probably fall well short - especially when recharged by solar PV which is generally a poor match to lead-acid requirements.Forklift batteries typically quote 1500 cycles @ 80% DOD - because forklifts owners don't want batteries any bigger than they need them to be so they need to be able to use most of the capacity.Car batteries? Forget them - they are designed for high currents for starting engines but very low DOD. You might only get 50 cycles if you deep discharge them.You might find this interesting as it provides a lot of detail as to why paralleling batteries is problematic:http://physics.ucsd.edu/do-the-math/2012/12/death-of-a-battery/https://www.google.co.uk/search?q=battery+tall+cells+corrosion+discharging+overcharging&biw=1252&bih=866&ei=6ZjUVevBMsutabbxiNAF&start=20&sa=NForklifts batteries are probably a good choice but they do have their own problems apart from their sheer weight. Being tall cells, stratification of the electrolyte is a problem which can lead to plate corrosion. To avoid this you need to charge them with enough gassing to mix the electrolyte - but this itself is damaging the cells through excessive overcharging. Alternatively you could use an air pump to bubble air through the acid.This provides some useful information:http://www.battcon.com/PapersFinal2013/11-Larry%20Meisner%20-%20The%20Effects%20of%20Mechanical%20Electrolyte%20Mixing%20VLA%20Cells%20in%20Renewable%20Energy.pdfYou can buy 2V 1000A forklift cells from BimbleSolar for £161 which at £80.5/kWh is the same as a 12V/110Ah £106 leisure battery - except it is rated for 1500 cycles @ 80 DOD. Again, I'm not recommending BimbleSolar, its just that they are about the only website I can find showing a price for a forklift battery.

author: Simon
author_rank: Unknown
timestamp: August 19, 2015, 05:05:02 pm
content: Quote from: max_torque on August 19, 2015, 02:37:36 pmI've already done the expat thing the other way around. If I've not bored the pants off you already about how crap italy is I can do next time your in. Every country has it's problems although most british expats i knew in italy were miserable bastards who lived in isolation thinking highly of themselves and that provided them with enough fun, if all you want to do is eat good food not a problem. I have no idea what the future holds, other than fuel and raw materials becoming more scarce and/or expensiveThere are other sources of power like economy 7 charging which I hear has been done and of course maybe a wood fuelled generator. Garden space is abundant if I had to and it became viable I could cover the whole thing in panelsand it's big enough to put another house on thanks to the substation being in the way of allowing some to do that before I got there.

author: Simon
author_rank: Unknown
timestamp: August 21, 2015, 04:14:16 pm
content: No that I've seen a datasheet yet but I can get 24x 2V 345A batteries for £1920 that's 16.5KW about 11p/W or 44p/W if i take into account only a 25% discharge and use 4KW of that. It does depend on what you buy as 8.4KW of a different not so commonly used cell type would have been £1440

author: nowlan
author_rank: Frequent Contributor
timestamp: August 23, 2015, 02:25:08 am
content: Am waiting to see if anything comes from Nickel-Iron and graphene.

author: Simon
author_rank: Unknown
timestamp: August 29, 2015, 07:33:42 am
content: well if i bought 16.5KW of batteries for £2000 and assume 25% dicharge for 4000 cycles, that is 4KWx4000 = 16'000 KW£2000 / 16'000 = £0.125 per KW of capacity, oh dear, I'm paying about that for electric,The panels themselves will pay for themselves in 5 yearsSo yes very financially unviablemight have to make it a grid tie system after all.

author: max_torque
author_rank: Super Contributor
timestamp: August 29, 2015, 01:09:38 pm
content: Can i suggest some research into "units"?? kW and kWHrs are not the same thing at all!

author: Simon
author_rank: Unknown
timestamp: August 29, 2015, 04:14:38 pm
content: ok, ok

author: Seekonk
author_rank: Super Contributor
timestamp: August 29, 2015, 08:12:49 pm
content: While not how to calculate it, he came up with the typical life cost for a battery KWH. With panels being cheap I run real time power and skip the battery bank. I have only a car battery for motor surge start currents and sequence loads. I run a fridge, make all my hot water and run the house for fie months of the year totally off grid. Everything is done by micro control. I hate batteries. They should be promoting new ideas here not retarded thinking.

author: Simon
author_rank: Unknown
timestamp: August 29, 2015, 08:26:02 pm
content: Well see I could pay for a grid tie system (£5000 and up) and get what I get or get one of those free installations where the installer gets to sell any I don't use (assuming they have not all gone bust). panels alone pay for themselves in 5 years, obviously I can't sell it back unless i use an official installer who will put them in the wrong place and cost me a fortune so after the 5 years of inefficient operation on my roof the installers time and the inverter and fixtures need paying for.But then I can't swallow the fact that the government has given preferential treatment to one company over another. essentially all home owners and installers are now gifting energy to the energy companies to sell at a huge markup well beyond accounting for a bit of profit and transmission costs particularly when you consider that all the transmission network I'd be using is what is on my on street!

author: splin
author_rank: Frequent Contributor
timestamp: September 02, 2015, 03:55:13 pm
content: Quote from: Simon on August 29, 2015, 08:26:02 pmErmm... what are you on about? I can't parse this statement into anything that makes any sense.What company has the government given preferential treatment to?How exactly are *all home owners* now gifting energy to the energy companies? Presumably you mean those with solar PV and other renewable generation? Are they not being paid far more for it through the feed in tarrifs (> £0.15/kWh) than the energy companies can buy it from the main generating companies (approx £0.05/kWh)?How are they supposed to "sell at a huge markup" when they actually have to sell it for around £0.11/kWh retail which is less than they are forced to pay for it?

author: Simon
author_rank: Unknown
timestamp: September 02, 2015, 04:58:57 pm
content: Quote from: splin on September 02, 2015, 03:55:13 pmI'm actually struggling to find any data on feed in tarrifs. I may be confused by government subsidy and amount energy companies are offering. It seems so far the government has been giving the money away to people with the money to install a system. I don't think that the government at this stage should be subsidizing the home generation market but then heaven fobid the government don't give money to people with money, today a solar syustem pays for itself in 5-6 years, if people want to invest, they should be investing. The subsidy is now going down to 1.63p/KW if so far most of the money paid for FIT if not all was from the government by the sounds of it so that begs the question, what will the enery companie be paying in 2016 ? of course as we abandoned price controlls on anything a long time ago, I think we all know how this will go.Mean while the government is fretting about the lack of capacity in the energy generation market due to a lack of investment by power companies who will now just smile, lean back in their comfy chairs and say "so how much money is the government willing to give us so that we can invest what we should have invested instead of taking it in profits" And we will all pay again! As it happens coal powered stations take i beleive 30 years to pay for themselves. I think the last one to be comissioned was on the back of a government loan with little to no interest.

author: Simon
author_rank: Unknown
timestamp: September 02, 2015, 05:01:48 pm
content: All I can find is here:https://www.gov.uk/feed-in-tariffs/overviewQuoteNow that makes no sense.

author: johansen
author_rank: Super Contributor
timestamp: September 03, 2015, 04:08:44 pm
content: Quote from: Simon on September 02, 2015, 05:01:48 pmin most of the usa you need a separate export meter to backfeed the grid and you will get paid at most half at most of the residential rate. so its utterly unprofitable.if you have one of the older meters you can back feed the grid and as long as you don't back feed more than you use in a month, they will never find out.however, that is against the fine print... (no, its not dangerous, buy a legit back feed generator)another option some people have is to back feed the grid no more than you draw from it at any given instant.but i haven't found an off the shelf solution that will do that.^this solution would be perfectly legal if you run your house from a doubly feed UPS. however it will cost you about 100 watts no load losses for a 10KW inverter.

author: Simon
author_rank: Unknown
timestamp: September 03, 2015, 04:25:48 pm
content: The problem is that things are volatile, you have 3 main points of interest driving the whole thing.1) the government who may or may not offer subsidies and may or may not put controls in place2) the energy companies who may or may not be regulated on how much they have to buy the electrity for3) the fact that there are rules on how much CO2 we produce and therefor potential incentive to spend the "fine" money in the nations own economy to provide a solution that prevents the fine occuring.Of course all this will be governed beurocratically and not with an engeneering head. To pay near 50p/KW was ridicolous. I firmly beleive in the industry supporting itself but it also needs not be at the mercy of radiacal changes in law and energy companies with no regulation. As far as i can tell the government has been paying over the odds and energy companies have possibly not been paying for the solar power, and I'm supposed to beleive they are about to.it looks like this site:https://www.abundancegeneration.com/how-to-invest/might even be a better idea, after all there is economy in scale and better return.

author: Aodhan145
author_rank: Frequent Contributor
timestamp: September 15, 2015, 11:30:20 pm
content: You have to get your system in before the tories tear everything to shreds.

author: Simon
author_rank: Unknown
timestamp: September 16, 2015, 05:09:02 am
content: bit late for that and if the big 6 were regulated on this there would be no problem. Obviously all the rish tory voters now have their systems installed so they can abandon supporting the market and not even bother to make sure that once again a huge company can rip you off if they wish. There is no real published data on what tarriffs actually are that I can find.

author: CatalinaWOW
author_rank: Super Contributor
timestamp: September 16, 2015, 05:11:07 am
content: I have been trying to justify putting in a solar system for 20+ years. It was just getting attractive financially to install a grid tied system in Arizona (about as good as it gets for solar energy) when I moved to a more northerly, forested and cloudy location. Pfft. It makes no sense here, and I suspect I am still both south of and in a less cloudy location than Simon.Twenty years ago people were acknowledging that the numbers didn't work out at current costs, but were predicting rapid inflation of electricity costs. It hasn't really happened. As always past performance is not a prediction of future performance, but my crystal ball isn't absolutely positive that electricity costs will go through the roof.Even for grid tied systems in favorable locations it is likely to get less attractive. The utility companies have recognized the threat to their business models and are starting to request tariffs for attachment to the grid. This is even justifiable in general terms. They do have costs in maintaining the distribution system, and also in making generation match consumption, which have historically been amortized in the electric bill. When people cut their grid purchases by 50-90 percent or more the costs of maintaining the grid don't drop by anything like the same percentage. The tariffs proposed seem out of line high relative to the actual costs, but who knows how that will settle out. Even a charge that matches actual costs hurts the economic case for solar.

author: Simon
author_rank: Unknown
timestamp: September 16, 2015, 05:21:35 am
content: the day electricity goes up panels will too, I'm sure we know the way markets operate fundamentally, its about how much can you get.As i said before I don't mind not being paid distribution costs but we will now be at the mercy of the companies that can do as they please, they have before and will again. When we had a cold winter and consumption went up they doubled their profits over that year, but because of the racus over prices kept them the same or they may have given a 5% cut because of huge cuts in wholesale price, so despite higher consumption, lower wholesale prices and a doubling in profits what did that do ? they claimed the 5% cut in prices had harmed them and made 2000 people redundant to cut costs. This is why my original plan was to go off grid, I know what they are like, we all do or we choose to ignore it.One day resources will get scare and they prices will have to go up.

author: bills
author_rank: Frequent Contributor
timestamp: October 03, 2015, 05:44:07 am
content: Quote from: CatalinaWOW on September 16, 2015, 05:11:07 amTen years ago the numbers did not match for me but I went ahead anyway total cost was 18k after rebates and tax credits.The system paid for its self in 8 years, my total cost for power is about $250.00 per year.Was 200-350 per mo.

author: mtdoc
author_rank: Super Contributor
timestamp: October 03, 2015, 06:05:48 am
content: 10 yrs ago, PV panels cost $ 5-10 per watt here. Now they cost $0.50 - 1.00 per watt, a 10 fold decrease.So today you can get more PV electricity production per $ in a relatively cloudy region (say NW Washington State where I live) than you could in a sunny area ( like Arizona) 10 years ago.

author: bills
author_rank: Frequent Contributor
timestamp: October 03, 2015, 06:12:23 am
content: I plan on adding 2 more 235w panels to max my inverter out and see if I can get to 0 cost per year should be a 2.5 year pay back.

author: Simon
author_rank: Unknown
timestamp: October 03, 2015, 07:58:39 am
content: Well somebody beat me to it. I was wondering if I would upset people if I replied to such an old topic. But today I should be getting six 250 W panels and a Sunny boy grid tie inverter for just under £1000. Not sure they are new but as long as they work I'm not too bothered.I abandoned the idea of batteries as obviously that technology is yet to mature. I think as electric cars develop the battery technology will come down as a side effect for other things. The grid tie inverter is anyway only meant for solar panels or at least so they say. I know I won't get paid for any of my energy which I estimate to peak at about 5 to 600 W per hour so if I am at home during the day that or something less will happily run my computer which is usually left on anyway and as others suggested I could time things to happen when the sun is out like my washing machine (that has a broken heating element anyway) and I am also an avid user of a dehumidifier as it means particularly in the winter that I can actually breathe through my nose and of course I have a fridge all things that would benefit regardless of whether I'm there or not. Of course by night meh I will have to pay.It is a pity that regulations are so tight and inflexible and dreamed up by stupid bureaucrats because at the end of the day the only reason why you need a certified system is so they can make sure they are not paying you to pump diesel generated electric back into the grid and get paid a packet. All they need to do is put the onus on the energy companies to come out and check that you really have the system and of course is going back into the grid and when making it very easy stop people defeating the system. Energy meters could also simply run backwards. If we work on the assumption that the technology should not be subsidised but pay for itself then this is by far the simplest and least bureaucratic method. You use it by night you put it back by day everybody is fair and square. Should you have a surplus which is extremely unlikely in the average home a sensible tariff could be agreed. Obviously this means that the energy you are effectively selling back is being paid at the same rate you buy it and the rate you buy it at also includes transmission costs et cetera. This is simply mitigated by a small increase in the cost of electricity. Yes I hear people crying that everybody would have to pay for that well we are all going to pay dearly somebody does not do something soon. As I mentioned at the beginning of this thread my motivations are more than just economical I just want to do the right thing. if People were incentive to to set up systems like I am the system cost would drop dramatically and it will be obtainable by more people.The reason why not going for one of those free systems is that I am sure they are already chock-a-block with requests and also my roof faces east and west exactly and is extremely unsuitable as it is also at a steep angle. Had I been in the house next door turned by 90° it would have been perfect. I doubt any of these freebie installers is going to want to put up a frame in my garden in just the right place to face the panels the right way. That is something I will do in my own time I have pretty much all winter now and the ground they would stand on is full of wood waiting to be given to a friend for his wood burner. Buying an official system is beyond a joke considering what I would actually get paid it's pointless trying to pursue the guaranteed payout I will have to lay more money down and probably be worse off financially.

author: CatalinaWOW
author_rank: Super Contributor
timestamp: October 12, 2015, 04:52:53 pm
content: Quote from: mtdoc on October 03, 2015, 06:05:48 amAgree costs are coming down, but still doesn't work for me. When I was in Arizona my electrical usage peaked in the summer months (surprise, you need AC in AZ in the summer.) That was a good match to the solar availability. I could size a system to provide a relative fixed proportion of usage year round. Didn't have to worry about how much the utility would pay for excess electricity I produced. My particular site didn't have any roofs oriented in a southerly direction so I either had to build structure or seriously oversize to the system to work out. Costs had dropped so much that even with these penalties it made sense.Now I live in SW Oregon. Electricity consumption peaks in mid-winter when geometry and clouds seriously limit solar production. In addition my site offers limited areas where trees don't provide significant shading. These restrictions make a system that provides enough power to put a dent in winter consumption very large and costly. Rates that utilities will pay for the excess power in summer don't help. Not surprisingly they don't need extra power in the summer either, since they have sized their systems for the high demand winter months.By the way, panel costs have dropped to the point where they are not the dominant cost in the system. Further drops in panel prices will not make dramatic changes in solar costs. The other costs in solar systems are in much more mature technologies which can't be expected to drop rapidly. Things like structures, brackets and wiring.

author: Simon
author_rank: Unknown
timestamp: October 13, 2015, 05:58:38 am
content: Yes my (new) inverter that I only paid £245 for actualy costs around the £1000 mark, this starts to dwarf the panel cost as the cost of panels to run it is little more than that. I'm at about halve capacity with so called 1.5KW of panel (which are new) that of course "up here" will only make 750W i estimate so i need another 6 250W panels to get to the 1.55KW the inverter can do.But even in autum as we are with the panels left flat on their back I'm getting 500W, it's a pity I have a large tree in my garden as it means i need to spent money to put the panels on a frame to increase their height. I got 250W at dusk but I think that was a specific combination of cloud as well that scattered back the sun rays that were in totally the wrong direction.

author: coppice
author_rank: Super Contributor
timestamp: October 13, 2015, 06:24:01 am
content: The Sunny Boy 1.5 seems to be under 500 pounds in the UK, so I assume your 1000 pound unit is some high end 1.5kW model. 500 pounds puts it in the ballpark of the panel costs. You have to mount panels on something substantial, even if they are laid flat, as they will blow away in a storm if you don't. That probably costs about as much as the panels or inverter. So, we seem to be looking at around 3 times the panel costs + installation. This is looking a lot better than a few years ago.

author: Simon
author_rank: Unknown
timestamp: October 13, 2015, 06:44:03 am
content: I've got the SB1700 which can actually do 1.55KW continous, neber mind the headline number of 1700:http://www.criticalpowersupplies.co.uk/SMA-sunny-Boy-SB-1700I won't be making too complicated a frame. I'll probably weigh it down rather than sink posts into the ground.

author: coppice
author_rank: Super Contributor
timestamp: October 13, 2015, 07:25:31 am
content: Quote from: Simon on October 13, 2015, 06:44:03 amAlthough Critical Power Supplies are still listing that model, it seems to be an obsolete one. The newer models seem to have halved in price for similar capabilities. Although these things use mostly mature technology, the growing size of the market does allow considerable reductions in price.... and, of course, growing competition pretty much forces their hand.

author: Simon
author_rank: Unknown
timestamp: October 13, 2015, 11:35:55 am
content: Well at 50% the retail price I'm still happy. It's cheap even for a second hand unit and it's new. Plus he had the decency to come and measure up cables for me and help me get the wires through my wall and crimp the connectors for me. All round I certainly can't complain.

author: EEVblog
author_rank: Unknown
timestamp: October 13, 2015, 11:45:48 am
content: Quote from: Simon on October 13, 2015, 11:35:55 amBargain!What is your feed-in tariff compared to your electricity cost?Although with a 1.5kW system you probably wouldn't be outputting all that much to the grid?

author: Simon
author_rank: Unknown
timestamp: October 13, 2015, 12:01:52 pm
content: There is no feed in tariff, I paid £930 for the lot and for another £660 can get the extra panels to make it proper 1.5KW.My roof faces the wrong way and to get the same gear installed by a proffesional (that would get me a certificate for feed in) would be £5-8000. So I'll build my own frame and have them up in the garden. If I'm home I use it all, if I'm not well....... what little I'd likely get would hardly have covered the cost of a pro installation.The problem here is that the government have been paying you for the electric and then selling it off at a loss to the energy companies. Now they have reduced the mandatory feed in tarrif to £0.0167/KW so unless your energy provider will pick up the difference your screwed and of course I've not heared of any regulations yet that force a minimum price.I doubt any of the companies offering free instalations would have bothered with my roof being the wrong way.

author: jnissen
author_rank: Regular Contributor
timestamp: January 11, 2016, 09:27:28 pm
content: Only makes sense if you live in a liberal hell hole like I do here in Austin! O0 One of the few places they actually believe you can use solar for power generation.The local utility gave me enough to cover roughly 60% of the cost of the system. The tax write off was worth more and now my utility company is paying me for every kW produced. I have had my system up for about four years now and in four more years it will be at a point where it will actually make money.Then again it's making money now but paying me back. I guess it was a good investment as it pays about 13% per year. My skills (or better yet my investment advisor) has not been able to find consistent 13% returns lately! Part of the fun of the system is just in monitoring it and seeing how much it's delivering back. I use micro-inverters (Enphase energy) so it's easy to see per panel contribution.BTW - I have enough room to use a ground mount system. The panel are facing due south so I don't have a lot of limitations from the orientation. Trackers were just not economically feasible. My power output is very consistent and about as optimized as you can hope for. Not a compromise by installing on a roof and hoping to get the correct angles. The only advantage a roof mount has is that it does provide shading for the attic. Add later costs for more expensive roof repair (it will need a new roof some time in the future) and a roof mount is a non-starter.Quote from: CatalinaWOW on September 16, 2015, 05:11:07 am

author: tggzzz
author_rank: Super Contributor
timestamp: January 11, 2016, 09:42:32 pm
content: Don't forget to factor in what your insurance company will say when you need to make a claim. Consider their wriggle-room w.r.t. not being able to prove the electrical, chemical and mechanical installations were sound enough that they themselves did not add to the risk.And if you think insurance companies won't try to wriggle, I have a bridge you might like to buy.

author: mtdoc
author_rank: Super Contributor
timestamp: January 11, 2016, 09:52:55 pm
content: Quote from: tggzzz on January 11, 2016, 09:42:32 pmShould not be an issue here in the US as long as UL listed equipment is used and proper permitting of installation is done.

author: tggzzz
author_rank: Super Contributor
timestamp: January 11, 2016, 11:06:22 pm
content: Quote from: mtdoc on January 11, 2016, 09:52:55 pmUNfortunately the OP is not in the US and is thinking of doing everything himself. Apart from that, you are spot on.

author: mtdoc
author_rank: Super Contributor
timestamp: January 12, 2016, 12:31:09 am
content: Quote from: tggzzz on January 11, 2016, 11:06:22 pmOk - I wasn't sure who you were responding to. And just as an FYI - in some states here, homeowners can be permitted and do FYI just like an electrician For example, in WA state were I live, I can go online and pull an electrical permit and do whatever electrical work I want - then call for an inspection when I'm done - no difference at all from an electrician. I did the DC work for my solar installation that way.

author: Simon
author_rank: Unknown
timestamp: January 12, 2016, 08:00:07 am
content: Well it's a comercial off the shelf inverter with any required approvals and it plugs in so I would not need to be an electrician to hook it up.

author: Mechanical Menace
author_rank: Super Contributor
timestamp: January 13, 2016, 04:43:31 pm
content: Quote from: bills on October 03, 2015, 05:44:07 amI spend a little more (at current conversion rates an extra $10) than your top monthly spend on electricity in a year. I think I should maybe look into a proper whole house system myself...

author: tggzzz
author_rank: Super Contributor
timestamp: January 13, 2016, 05:51:51 pm
content: Quote from: Simon on January 12, 2016, 08:00:07 amI can't comment on whether that is sufficient. My cautionary tale about insurance companies' SOP...I was rear-ended in a queue of traffic; I moved forward and stopped, the person behind me moved forward and didn't stop. That's pretty much the prime example of a "not-at-fault" accident.The insurance company sent around a loss adjuster, and thefirstthing he did was look at my tyres. If you think about it, they simplycannothave beenrelevantto the accident let alone the cause of it!Why? Because if the tread was too low or anything else amiss, my car would have been "unroadworthy" - and therefore he wouldn't have needed to assess the damage.Don't presume that insurance companies aren't adept at wriggling out of what you think they might owe you.

author: Simon
author_rank: Unknown
timestamp: January 13, 2016, 06:00:06 pm
content: I try and hope not to rely on insurance companies. they are certainly not in the business of paying out.

author: tggzzz
author_rank: Super Contributor
timestamp: January 13, 2016, 07:12:14 pm
content: Quote from: Simon on January 13, 2016, 06:00:06 pmJust so. If you can swallow a loss, don't bother with insurance. OTOH, I'm no longer prepared to risk losing house and contents, so they are insured!As with all these calculations, it comes down to an individual's assessment of the maximum plausible loss - plus how easy it is to mitigate the loss or probably of loss.

author: Simon
author_rank: Unknown
timestamp: January 13, 2016, 07:38:48 pm
content: oh I'm insured. But I often see instances when driving where I miss having an accident that would not be my fault and would get blamed for anyway. I have had two car accidents aready both not my fault but both deemed to be my fault. Insurance is not a guarantee.

author: tggzzz
author_rank: Super Contributor
timestamp: January 13, 2016, 08:00:08 pm
content: Quote from: Simon on January 13, 2016, 07:38:48 pmJust so. The worst outcome is that after the event you find you weren't covered because they deem that you had invalidated a precondition.When buying insurance I don't bother to look at what's covered, I go straight to the Ts & Cs to understand the exclusion clausesOr is that

author: Seekonk
author_rank: Super Contributor
timestamp: January 13, 2016, 08:13:35 pm
content: Time to get one of those $20 dash cams.I have a second home that is totally off grid that is used five months a year. I've built most of the electronics and no rebates on the panels. Still the payoff is pretty quick not having to pay monthly service fees alone. Only about 1500W and it provides all my hot water and just two car batteries for storage. One is out of my car which I don't bring and the other is the boat battery when not in the boat. Scheduling and prioritizing replace massive storage. And a change in lifestyle. Incidentely the utility company at my other home says I use twice the electricity of my average neighbor.