What happened to the DIY in solar! - Page 1
Forum section: electronics / general

author: fourtytwo42
author_rank: Super Contributor
timestamp: May 31, 2017, 07:56:29 am
content: Seems to me all I read about here is buying this that and the other or who is the best installer etc and that is common among most sites I look at. As far as I can see in the UK at least with the current feed in tariff rates a fully commercial installation (required to attract tariffs) is just not economically viable as the payback time is longer than the equipment life.However for those of us determined to do our own thing buying at component level the silicon cost has dropped dramatically over the last few years and I heat all my water in summer using PV (and save some fuel in winter). I must admit to buying panels as they were cheaper than I could make them but everything else is entirely DIY.So all you latent electronic/software engineers post some systems here too

author: DenzilPenberthy
author_rank: Frequent Contributor
timestamp: May 31, 2017, 01:09:53 pm
content: ... designing something from scratch then building it from retail parts is always going to be vastly more expensive than buying a commercial product.Unless you value your own time at £0 per hour which I don'tAdd in the fact that you won't get a feed-in tariff paid if you use home-made and installed equipment. Also good luck convincing your house insurance company that it's all legit!The only case I see for DIYing stuff is where you want something that's not commercially available cheaply.

author: tszaboo
author_rank: Super Contributor
timestamp: May 31, 2017, 01:40:07 pm
content: I guess they dont want you to feed in more solar energy, but do the so called self-consumption. Dont you use net metering in the UK? If so, just size the system to your yearly usage.

author: JacobPilsen
author_rank: Regular Contributor
timestamp: May 31, 2017, 03:37:37 pm
content: DIY PV is banned here in CZ.

author: Seekonk
author_rank: Super Contributor
timestamp: May 31, 2017, 03:43:52 pm
content: That picture may be why. I assume those are lethal voltages. Don't even see an earth connection.

author: fourtytwo42
author_rank: Super Contributor
timestamp: May 31, 2017, 05:54:46 pm
content: Quote from: DenzilPenberthy on May 31, 2017, 01:09:53 pmWell I don't charge my time to what is essentially a hobby and I shouldn't think anybody else does either so I don't buy that argument. Sorry I didn't mention I was getting FIT's and I don't want them. Why do you think it involves the house insurance company ? Well I guess you must be a golfer or something other than an electronics/software hobbyist then

author: fourtytwo42
author_rank: Super Contributor
timestamp: May 31, 2017, 05:55:52 pm
content: Quote from: JacobPilsen on May 31, 2017, 03:37:37 pmAt what level, grid interconnect ?

author: fourtytwo42
author_rank: Super Contributor
timestamp: May 31, 2017, 05:57:33 pm
content: Quote from: Seekonk on May 31, 2017, 03:43:52 pmNo more lethal than many other items without an earth connection, its called double insulated and tooled entry.

author: fourtytwo42
author_rank: Super Contributor
timestamp: May 31, 2017, 06:00:23 pm
content: Quote from: fourtytwo42 on May 31, 2017, 07:56:29 amPerhaps I can answer my own question, seems to be a lot of negativity around, perhaps your all pro PV installersanybody got anything positive to say ?

author: james_s
author_rank: Super Contributor
timestamp: May 31, 2017, 06:02:16 pm
content: Wouldn't it be safer *without* an earth connection assuming it's not grid tied? It's a floating source, you don't earth battery powered devices.I've thought about setting up a small PV system to power DC loads like my internet router and hubs and such. Just stuff that is relatively low power but it on constantly. It would be fairly easy to feed them from a battery that is float charged from some small PV panels.

author: fourtytwo42
author_rank: Super Contributor
timestamp: May 31, 2017, 06:20:47 pm
content: Quote from: james_s on May 31, 2017, 06:02:16 pmExactly then if you touch something your not completing a circuit to earth! But like I say its all tooled entry and double insulated anyway with warning signs NOT connected to the grid in any way.I was originally thinking along your lines as there is loads of stuff in this house running continuously consuming background power BUT then I realised how they were spread all over and joining them with an LV bus would be lots of wire or bring them all together. Also here in the UK the smaller PV's have quite a high cost/W I guess because there designed for recreational use. That's when I started looking bigger and using them for water heating, that saves a lot more energy than the background load of bits n pieces and my boiler doesn't have to run in the summer anymore. Downside is the capital investment is bigger but I dont think anymore complex. All depends if you enjoy doing it or are going to charge yourself for your labour

author: mtdoc
author_rank: Super Contributor
timestamp: May 31, 2017, 06:37:56 pm
content: With respect to DIY solar installations using commercial products - PV panels, inverter, and charge controller/batteries (if off grid or grid-tie with battery back-up), then the DIY installer will definitely save a lot of money compared to using commercial installers (and their inflated PV prices). This kind of installation can easily be done safely and will usually require some type of electrical inspection by local authorities.Building the DIY power electronics - charge controllers and inverters - on the scale needed to power a house is an entirely different matter. While I'm sure there are people on this forum with the skill and experience to do this safely and efficiently, I doubt 99% of DIY'ers could accomplish that.The quality commercial charge controllers and inverters capable of powering a typical home are not cheap for good reason. There is a lot of metal there and a lot of engineering.On the other hand, small scale "power a shed" type of DIY systems with home made charge controllers are common and can be made easily and safely. This is done all the time and there is tons of stuff on the web detailing these. These are usually small DC only systems. Rarely have I seen any small AC systems with DIY inverters.With respect to grounding - It gets complicated with battery based systems in the US due to the NEC's requirement for ground fault protection. For an excellent discussion regarding some of the issues involved seeHERE

author: metrologist
author_rank: Super Contributor
timestamp: May 31, 2017, 07:37:31 pm
content: several years ago I saw on the youtubes one could buy the small crystaline wafers to build up your own panel. They were about $10 each back then. Is that still available?

author: rob77
author_rank: Super Contributor
timestamp: May 31, 2017, 07:46:50 pm
content: Quote from: fourtytwo42 on May 31, 2017, 05:55:52 pmi assume you can't connect it to the grid... but no-one can stop you building your own solar system which is NOT connected to the grid.

author: hendorog
author_rank: Super Contributor
timestamp: May 31, 2017, 09:06:33 pm
content: If you can find a retailer who will sell you spot priced power then you can get away with a much smaller PV + battery system. No need to feed anything back into the grid so you can bypass that mess.I reckon that is the future, spot pricing with distributed storage and/or generation at the households covering the peaks. You heard it here first folks.

author: Someone
author_rank: Super Contributor
timestamp: June 01, 2017, 02:51:27 am
content: Quote from: metrologist on May 31, 2017, 07:37:31 pmIndividual cells are much less than a dollar each, even 10 years ago. But the other materials to make a useful outdoor panel are still expensive and require specialised equipment or skills to assemble, so its much cheaper to buy assembled panels wherever possible.

author: Seekonk
author_rank: Super Contributor
timestamp: June 01, 2017, 07:59:57 am
content: A 2011 discussion on grounding. Where have you been?https://www.homepower.com/articles/solar-electricity/design-installation/code-corner-earth-shifting-change-grounding

author: Codebird
author_rank: Regular Contributor
timestamp: June 01, 2017, 01:12:52 pm
content: I built my own from-scratch charge controller as a personal project. It has the feature set and capabilities you'd expect of a mid-range PWM controller, and cost about the same in parts - but a lot more if you factor in time as well. And there we have it: Even if you don't need the certifications required of grid tie, off-the-shelf solutions are just as good as anything one of us could build and lower in cost. The only reason to build your own is if you either have some very unusual requirements or just like the challenge of designing and building your own electronics projects.

author: fourtytwo42
author_rank: Super Contributor
timestamp: June 01, 2017, 03:00:59 pm
content: Quote from: Codebird on June 01, 2017, 01:12:52 pmI might disagree with you on both counts, cost and as good as! Myself I can usually build something substantially cheaper than I can buy (not counting stupid labor costs) and a better quality/more reliable. Having helped other people repair the horror stories they have bought I am fully aware of commercial build "quality" and "reliability" and want none of it!I think the problem here is the same as many other "renewable" discussion groups, it's infested with commercial interests trying to sell you some simple function at some exorbitant cost with all sorts of claims (pseudo science) attached. Not a place for genuine hobbyists or engineers to discuss anything sadly!

author: Seekonk
author_rank: Super Contributor
timestamp: June 01, 2017, 03:04:42 pm
content: A quote I saved from HOMEPOWER about how crappy systems are today and why I design my own to schedule and divert power. But, it is true that if the systems were better almost no one would be able to set them up. Fridges should store cold at peak sun periods and water should heat for example. Part of the move to smart appliances that might be utilized in ten years. My design was almost free, a post consumer product.This is a fascinating arena for creative homebrew, but “turnkey” products are rare. It’s sad to think of all the solar energy that is wasted becausemanufacturers and installers consider it such a low priority.

author: fourtytwo42
author_rank: Super Contributor
timestamp: June 02, 2017, 06:45:22 am
content: Whats happened to the DIY PV debunkers, given up! I replied to your points and got no responses, does that mean your going to stop trying to discourage me and others with your hocus pocus now ?

author: mtdoc
author_rank: Super Contributor
timestamp: June 02, 2017, 06:51:59 am
content: Quote from: Seekonk on June 01, 2017, 07:59:57 amThe origin of some of the recent NEC changes outlined in your Homepower link re: grounding can be found in that very same 2011 discussion. The bureaucracy is slow to catch up (and in some cases never does).Your Homepower link only outlines the changes in the 2017 re: grounding and does nothing to explain the underlying issues. The discussion I linked to presents a much more thorough exploration of some of the practical issues that arise with respect to grounding in battery based systems. In particularthis paperlinked in that discussion and authored by one of its participants, does a good job expounding on some of the conflicts which arise due to the NEC's GFP requirements.

author: DenzilPenberthy
author_rank: Frequent Contributor
timestamp: June 02, 2017, 10:37:42 am
content: Quote from: fourtytwo42 on June 02, 2017, 06:45:22 amI'm not trying to discourage you. I'm merely pointing out that personally I have a limited amount of free time so I have to allocate that to things I want to do.Designing an MPPT solar charge controller, mains battery charger, coulomb-counting battery monitor and a good quality 500VA inverter, all with bluetooth connectivity and an Android app to view all their parameters and history etc would be a fascinating and enjoyable project. It would also take up at least a couple of years of my time available to work on such things. So instead I just bought them. For not very much money. Certainly much much less money than I could earn if I spent the same amount of time doing paid side-work. This frees up my time to work on higher priority or more important things, for example renovating an old caravan which the solar kit is for. ... and be ready in time to go to Glastonbury in a couple of weeks' time.If I want something which isn't cheaply and easily available off-the-shelf then I'll consider building my own but that has to be prioritised with other things I want to do with my non-infinite time.

author: Codebird
author_rank: Regular Contributor
timestamp: June 02, 2017, 02:05:03 pm
content: If anyone does want to give it a go, I have published my design for a PWM controller - it's good up to 200W (any more than that you'd want MPPT anyway) and included fully software-definable charge cycle management and serial port output of all readings.

author: fourtytwo42
author_rank: Super Contributor
timestamp: June 02, 2017, 06:01:13 pm
content: Quote from: DenzilPenberthy on June 02, 2017, 10:37:42 amAnd so why make a comment upon a thread entitled DIY SOLAR! Dont bother answering please.

author: sokoloff
author_rank: Super Contributor
timestamp: June 02, 2017, 06:25:30 pm
content: By all means, let's not have a discussion about the relative tradeoffs of other engineering solutions to a problem.We should only discuss the specific route a poster has chosen, nothing else...

author: fourtytwo42
author_rank: Super Contributor
timestamp: June 03, 2017, 07:36:13 am
content: Quote from: sokoloff on June 02, 2017, 06:25:30 pmYou are quite right, my language was intemperate BUT I have recently suffered mightily from trolls elsewhere.

author: Red Squirrel
author_rank: Super Contributor
timestamp: June 03, 2017, 07:50:30 am
content: The idea of going DIY on the electronics is intriguing and something I've considered. Need to learn more about SMPS design and get to know all the ins and outs first, especially on the safety and failsafe side of things. Ex: if it fails you don't want it to take out a bunch of other stuff with it. Especially at the inverter you would not want it to fail in a way where it presents destructive voltage/frequencies to what is connected to it. Or even the charge controller, you would not want it to kill the battery bank.What would also be interesting is DIY battery cells. Seems lead acid is not THAT complicated, though the issue is getting the raw materials and the acid itself. But if one can come up with a design and a way to manufacture it consistently you could whip out cells made from like 5 gal pails or something and have crazy reserve time for way cheaper than buying the equivalent batteries. Though I guess it might make more sense to go lithium ion at this point if you were to DIY on the batteries. Issue is they have a more complex charging profile. Not sure how you'd charge a battery bank while it's also in use, which is essentially what happens in a solar setup. I'm sure there's a way to do it though.

author: fourtytwo42
author_rank: Super Contributor
timestamp: June 03, 2017, 08:17:33 am
content: Quote from: Red Squirrel on June 03, 2017, 07:50:30 amThe reason I do it is to keep the grey matter ticking over as much as anything but also I am intrigued with all the different possibilities and by doing DIY I can wring many idea's/answers from one setup, nothing is ever finished, it's always work in progress to the next trial/improvementI am fortunate to have some professional experience in SMSP/Converter design so I have a starting place, as you say boiling batteries or fire are serious consequences of careless design. There are unfortunately a lot of dangerous designs floating around on the web so it is not a good thing to copy. One of the best routes to getting started is manufacturers application notes that often include details of magnetics etc, TI & ON semi are good (Natsemi got swallowed by TI and Fairchild by ON).Fortunately PV is fairly safe as the input current is self limited by the cells to ~10A, High voltages can be avoided by limiting the length of strings employed and converter topology (avoid boost and flyback). Certainly no inexperienced person should attempt grid-tie as both the voltages and potential energies are high. If you want to avoid boiling batteries a transformer coupled design is good as if a mosfet fails the result is no output!I have seen home built batteries in oil drums on the web somewhere, intriguing but I am not sure where to get hold of large quantities of electrode materials. I think about Lithium and my mind immediately springs to fire so I have not been tempted even though I have several applications, again I have seen many DIYers using Chevy Volt packs and similar, if I did something I think it would be in a shed down the bottom of the garden

author: Codebird
author_rank: Regular Contributor
timestamp: June 06, 2017, 07:39:27 am
content: If you are building your own batteries, perhaps nickel-iron would be a better option? As for acid, well... I got two litres of concentrated sulfuric on eBay once.