Off Grid PV DIY Install - Page 1
Forum section: electronics / general

author: zeke.
author_rank: Contributor
timestamp: February 05, 2022, 04:50:03 pm
content: Im looking to install my own off grid PV system (not sure how large but lets just say a 6kW system). I want to build this myself with some help from my cousins.If I want to connect it to my house, do I need call my utility company and tell them to disconnect me or is there a way I can leave my grid connection and have a disconnect switch at my house. I would only connect myself back to the grid if my off grid system is down.

author: geggi1
author_rank: Frequent Contributor
timestamp: February 05, 2022, 06:12:33 pm
content: You probably got a main breaker somewhere in your electrical installation. This breaker can be fused or just a isolator.Some engineering on the size of your battery bank must be done also regarding low sun in the winter time.In the summer you might have more power than you need and if your distribution company are interested you might be able so sell some power back to them. By selling back power you will be able to break even in the investment earlier.By having the possibility to selling back you will also have an option of getting power form the grid in case something happens to your PV installation.

author: tggzzz
author_rank: Super Contributor
timestamp: February 05, 2022, 08:36:43 pm
content: Get the power company involved.They are interested in fault conditions e.g. the mains is down, people are working on the line, and your setup unexpectedly back feeds lethal voltages to them.

author: Faringdon
author_rank: Super Contributor
timestamp: February 05, 2022, 09:06:41 pm
content: Quote..Great statement....thats what kills off this otherwise good idea. Your system woudl have to have some failsafe way of never putting your power system voltage back on the line when the line is down......and its just not possible for the power company to allow this....just think of thousands of people with an islanded system like you propose.......it only takes one of them to have their safety disconnect fail and the linesman gets electrocuted.The only way really is to have two totally separate mains wirings in your house...and your island system never gets connected to the grid system.Then again , maybe their is some kind of huge mechanical changeover switch which breaks one and makes the other, and could never connect your system to the grid....i bet the power company woudl want to inspect it...and would thereby demand to see the official electricians certificate for wiring up all your islanded system.

author: themadhippy
author_rank: Super Contributor
timestamp: February 05, 2022, 09:28:30 pm
content: QuoteTheirs loads,either manual or electrically operated,and 6kw is piddly not huge

author: daveismissing
author_rank: Contributor
timestamp: February 05, 2022, 10:17:52 pm
content: There are manual changeover switches designed to switch 2-3 key circuits over to generator power safely, even Amaz has them. Probably all you need with only 6KW available. If you want to switch the whole house over better talk to an electrician.

author: zeke.
author_rank: Contributor
timestamp: February 06, 2022, 02:37:08 am
content: Well I wanted to build this all myself and have this off grid system powering the same loads the mains would. I would definitely have a mechanical switch that separates mains and the PV so they can't operate at the same time.Regardless, I will consult with an electrician before I do the build.

author: bdunham7
author_rank: Super Contributor
timestamp: February 06, 2022, 03:50:22 am
content: You simply need a manual transfer switch, which then will have a second circuit breaker box that you'll transfer some or all of your circuits to. This is the same concept as having a standby generator, except you'll be in 'standby' all of the time.

author: PaulAm
author_rank: Frequent Contributor
timestamp: February 07, 2022, 11:54:48 pm
content: If you wire it as a backup generator (ie, use a transfer switch so it has no possibility of connecting to the mains), then you do not have to talk to the utility and only have to satisfy your electrical inspector. I think most US states will allow you to do your own work as long as it passes inspection.Transfer switches (even manual) can get really expensive, particularly when you get to 100A and above. The last time I looked 200A transfer switches were > $500USD and they're just a box with a big knife switch in them.If you get interested in selling power back to the utility, there are a couple things to remember. 1) Most utilities are getting rid of net metering, so they want to charge you for every watt going across their meter, regardless which direction it's going. 2) If you connect to them, you have to enter a co-generation agreement and they can specify how big your array can be. They do not want you getting a free ride despite you putting up the capital for the array.I built and wired my house, so I have 200A transfer switches immediately after 200A breakers which are immediately after the utility meters. I can flip the breakers and work on anything without worrying about the utility feed. I wired my system for a large backup generator with the ultimate aim of being off grid using solar/wind. Instead of having a generator subpanel with specific loads, it just transfers the entire house over, which is what it sounds like you want to do.Storage is the big problem, to be off grid you need several days of storage and I suspect 6kw of panels is a bit low. They're not as effective in winter so you might need more panels to cover the load even though you might be over capacity in the summer.You might look into buying used solar panels. I have a 10KW array and picked up another 25KW of panels this year and the price was around $0.25/watt, delivered. The panels, of course, are about the cheapest part of the system.

author: NiHaoMike
author_rank: Super Contributor
timestamp: February 08, 2022, 01:44:13 am
content: You can consider making it a "zero export" system, thereby eliminating the hassles with exporting. Downside is that you'll need storage to get good utilization, but a few kWh of EV battery modules combined with automated load management can do that quite well. You'll still need a transfer switch to get automatic backup, but it can be much smaller as it would only have to handle the loads you want backed up.Just make sure to check the exact capabilities of the inverter, many that claim to support "zero export" only support that for loads connected to the output and do not have the external sensor connections needed to zero export to upstream loads. As far as I know, only Sol-Ark supports both zero export to upstream loads and built in backup.

author: zeke.
author_rank: Contributor
timestamp: February 10, 2022, 09:45:54 pm
content: Quote from: PaulAm on February 07, 2022, 11:54:48 pmThanks for the info that was a big help. Do you have a battery storage system with your panels?Quote from: NiHaoMike on February 08, 2022, 01:44:13 amThanks, I will keep that in mind when looking at inverters. Is there any reason to have a manual transfer switch than an automatic one?

author: free_electron
author_rank: Super Contributor
timestamp: February 10, 2022, 10:00:23 pm
content: Quote from: zeke. on February 05, 2022, 04:50:03 pm- you will need a licensed electrician- you need permits- you need to get this inspected both by city/county and the power company.- you will need to submit detailed plans and get them approved.- in most states it is illegal to not have a power connection ( mandatory ) . you don't have to use it. but the wire to the house and the meter needs to be there.6kw won't cut it. if you want to go offgrid you need to account for nighttime. so during daytime you need to produce for both daytime and nighttime and store it. take a look at your current power consumption month to month over an entire year and find what is your maximum consumption month. That's your starting point. keep in mind that most big consumption happens late afternoon till 9pm ! ( assuming you are not home during the day ) people arrive home at 6pm, start cooking, washer , dryer, airco / heating ... when the sun is not producing a lot anymore...I run 'quasi' offgrid. In the sense that i export more to the grid than i pull from the grid (over an entire year). Summertime my draw is zero and i export. Winter i draw a bit mainly for car charging, but it is offset in the summer. My monthly bill is 3$56 which in the fee for the power meter. I have a 18Kw solar array (48 panels) and 56KWh in storage (4 Tesla powerwalls). Whole house is electric (no other energy sources), including electric car.

author: PaulAm
author_rank: Frequent Contributor
timestamp: February 10, 2022, 11:19:39 pm
content: QuoteLocal and state requirements are all over the map. You may not need a licensed electrician (or you may, my state doesn't require it. In my case, I installed the meter boxes and everything on the house side, the utility ran the feed and installed the meters)You will need permits. You may need zoning approval for the array (and maybe not)You will need inspections by your local inspector (building and electrical). The power company may or may not care.Your building inspector will need approval on the plans. If you use a ground array, they may need engineering drawings to demonstrate it will handle wind and snow loads. Use a commercial rack and the vendor will have engineering drawings you can use. Don't build it out of 2 by 4s.Get to be friendly with your building and electrical inspector. Try not to argue with them, that won't go well. In fact, you might want to have a friendly chat with your local inspectors before you start to get an idea of what they would be looking for and what works well in your area. Bring donuts. They will be happy to point out potential problems to you (if you avoid them, it makes their job easier).I have a 10KW ground array and had to coordinate with my utility because I'm connected under a net metering agreement (which ends in 4 or 5 years). That was the largest the utility would allow. They had to do an anti-islanding test before I could turn it on and approve the size, but they didn't care too much about the details other than making sure the inverters were acceptable for grid tie use. I was completely unimpressed with the utility people, they screwed up right and left and some were complete idiots. From my conversations with my inspector, my experience was not uncommon (we also have among the highest electrical rates in the country and we had a 4 day blackout last year and we can't blame it on wildfires)When my net metering agreement ends, I will triple the array size, add storage and go off grid. I'm hoping for better storage options by then.Apparently, in my neck of the woods, people don't like to see solar arrays. The zoning guy gave me a limited number of possibilities over where to locate it. Rooftop might have been easier, but I can clear the snow from the ground array without problems. My neighbor has a rooftop array and it's been covered in snow for 2 weeks.So all kinds of things to consider, but you need to identify your local requirements before putting a plan together

author: NiHaoMike
author_rank: Super Contributor
timestamp: February 11, 2022, 02:34:45 am
content: Quote from: zeke. on February 10, 2022, 09:45:54 pmJust cost, even then there are relatively cheap ATS modules although they tend to be on the slow side to switch. Some inverters have the transfer switch built in which is likely to be faster than any external transfer switch, but they're pretty limited in capacity. If you already have a subpanel for essential loads, that can work well.

author: zeke.
author_rank: Contributor
timestamp: February 15, 2022, 03:57:33 pm
content: Quote from: free_electron on February 10, 2022, 10:00:23 pmI should of mentioned, this is for a house that’s in the middle of nowhere in upstate NY. We only visit it on the weekends so I was thinking a lower power production and larger power storage. If there is extra power generated during the weekdays, we could install a filter in our pond that only runs on extra power generated.How much did your offgrid set up cost? Also any regrets you had during the process of building it? Sounds like you are fully invested into it.

author: zeke.
author_rank: Contributor
timestamp: February 15, 2022, 03:59:04 pm
content: Quote from: PaulAm on February 10, 2022, 11:19:39 pmThat was some great info, thanks!

author: DougSpindler
author_rank: Super Contributor
timestamp: February 19, 2022, 11:57:16 pm
content: Where are you located?If you are in California and a PG&E customer solar no longer makes sense.On August 1st PG&E new solar rates are being phased in making solar more costly than buying electricity from the grid. Payback for my solar system with PG&E was just under 5 years. When PG&E lowers the rates in August the payback will be nearly 75 if not 100 years.Before spending $15,000 to $20,000 for solar panels take a look at your power companies rates.

author: NiHaoMike
author_rank: Super Contributor
timestamp: February 20, 2022, 12:09:47 am
content: Quote from: DougSpindler on February 19, 2022, 11:57:16 pmYou're horrible at reading.Quote from: zeke. on February 15, 2022, 03:57:33 pm

author: DougSpindler
author_rank: Super Contributor
timestamp: February 20, 2022, 12:11:22 am
content: Missed that part.