diy solar

diy solar

Thoughts and plans of someone new - it's long.

moose09876

New Member
Joined
Dec 28, 2021
Messages
8
Just posting this here for anybody enjoys brainstorming and finding new solutions like I do.

Environment (midwestern Indiana):
1 Main 200A 30 slot panel
1 Secondary main 100A 24 slot panel in detached 4.5 car garage (2.5+2, lengthwise)
Room for 20-22 panels south facing, full sun
Full detached garage available facing east/west, almost full sun. Est. 40 panels (future)
Plan to have 1 electric car/truck/suv, and one electric motorcycle in the next 1-10 years, with an additional car/truck/suv close or after. Currently we both work from home, 2 dogs, no kids, lots of tech, lots of hobbies.
Electric stove, clothes dryer, 2 12kbtu inverter mini splits, and a 3ton 2 stage A/C. Hot water heater and furnace are both natural gas.
All our home lights are LED, the main draws are home theater, microwave, NAS/gaming PC, other 110V cooking implements.
I also have a shop with all 110V air compressor, welder, 1/2hp lathe, 1/3hp mill, 1hp grinder, etc. Nothing essential, but information to have.

Goals:
1) Offset grid cost. All the installers focus on a $0 bill right now, which is not one of my goals and really puts me off the installers. Price is rising, usage is rising, I'd like to get something in place that can grow with us and be financially feasible.
2) Expandability - more PV, more battery, more inverting power. I don't want to be stuck down the road.
3) Provide at least some UPS / grid down functionality. Longest we've been without power was 30 hours in the last 10 years, but it gives me unnecessary stress.

The lobbyists won, so net metering here is dead. No choice other than zero export. Average current usage is ~1800kwh/mo. We will never be off-grid here.

I'm a DIYer, so an off the shelf solution or paying for full install is off the table. For this area and potential benefit, the cost is just too high. The best plan I've come up with so far is (and I'll try to make this make any sense) - Keeping the main grid feed to the 200A panel along with the dryer, stove, and main A/C. I consider these very power hungry and not completely necessary. 60A breaker off the main panel would feed an Outback Power Skybox. Additional 60A would backfeed an interlocked subpanel (see below). The Skybox seems to integrate all the functions I'm looking for and are outdoor rated to save space in the garage. ~8kw PV on the attached south facing garage would feed into the Skybox. That would then feed a subpanel in the house that houses all my loads (except dryer, stove, and 3ton A/C). That panel would have an interlock and be backfed from the 60A breaker mentioned above for the option to switch back to grid if necessary. I can't put all my eggs in the inverter's basket. Battery for the Skybox would be a server rack style 100AH 48V Battery, planning on starting with 2 with the option to expand this bank. The Skybox has CT's that can monitor the mains to insure zero export. My hope is that I won't need an additional skybox for my loads, but if I do, I'll just move the necessary circuits back over to the grid connected box until I get the future skybox installed.

Future:
After electric vehicle adoption.... Add however many panels I can fit on the detached garage both watts and space wise, and add another Skybox in parallel with another 2+ battery bank in the detached garage. The Skyboxes communicate with each other and the consumption monitor to adjust the output to maintain zero export. Another major benefit to using the Skyboxes is if the dumb laws here ever change, they can be reconfigured for net metering.

I antagonize over everything, something this substantial is a lot. Would love constructive opinions on what I missed / haven't thought of / found. Thanks!
 
The lobbyists won, so net metering here is dead. No choice other than zero export. Average current usage is ~1800kwh/mo. We will never be off-grid here.

That average is easy to generate, maybe not so easy to store.
1800 kWh/month / 30 days/month = 60 kWh/day
60 kWh/day / 5 hours effective sun/day = 12 kW PV
$12 kW PV / $1/watt DIY PV system = $12,000

That gets you a grid-tie system.
A bit more and you can have a hybrid inverter (e.g. SolArk) or AC coupled SMA.

Batteries are the killer. $0.05 to $0.50/kWh of cycle life. Best if you can use power as it is generated, rather than storing.
With DIY LiFePO4, you could build a 48V 208 Ah battery for about $2500, around 12 kWh usable. Five of those to store one day's power, $12,500.

So somewhere around $25k, more or less depending on how long you want to get by without sun and without running a generator. If grid is available, use that as your generator. Maybe thermal storage can reduce need for battery. But heat in winter will be the challenge.

Regard lithium batteries as potential incendiary devices, and situate them where they can't burn your house down.
 
I antagonize over everything, something this substantial is a lot. Would love constructive opinions on what I missed / haven't thought of / found. Thanks!

See what deals remain on DC Solar trailers.
The GNB forklift batteries may or may not have survived neglect.
The pair of Sunny Island would be a good start of an AC coupled system, and 2400W of PV with Midnight Classic 250 serves as a starter PV system.
Then look for used and old stock Sunny Boys.
 
Water source?
Well pumps are a key load, starting surge needs to be considered.
 
Thanks for all the replies.
1) Your calculations are spot on with estimates I've done. At this point it's more about hours of backup vs. number of days. I foresee this getting worse by the time this system is exhausted, but for now, this is what I'm solving for with plans for the future.
2) LiFePO4 I wouldn't consider a fire risk. Lithium ion, yes. Everything has risks, but having them safely stored away from the living area is enough risk-averse to me.
3) For the space I have available, the panels / spaces I've outlined are the only feasible places for panels
4) Water is a submersible well pump, 35'. I'll have to measure starting load, but appears to be minimal. could always switch it back to grid till I expand.
 
We're aware here of a few LiFePO4 fires.
DIY rather than UL Listed ESS would put your insurance at risk.
Therefore, I suggest "better safe than sorry".

My system is grid-backup, and I've had net metering at least so far. So my battery is only big enough for one night, and it is AGM.
If NEM 3.0 is adopted as proposed so I get zero benefit from exports, I'll consider my alternatives. Since most batteries other than DIY lithium cost more than grid, they wouldn't give a financial benefit.

AC coupling I'm supposed to have 100 Ah (at 48V) for each 1kW of GT PV, but I have about 1/3 of that. A DC couple system could have smaller battery. It works well for loads like A/C during the day.

Small pump is probably easy to start. Surge current 5x running is my estimate, so inverter needs to supply that.

Because you have natural gas, a quality generator could pick up the load after a very small battery. "Combined Heat and Power" could use the waste heat for your house while also charging batteries. There are fuel cells too, but I would guess cost, lifespan, and overhaul options aren't competitive.
 
Just posting this here for anybody enjoys brainstorming and finding new solutions like I do.

Environment (midwestern Indiana):
1 Main 200A 30 slot panel
1 Secondary main 100A 24 slot panel in detached 4.5 car garage (2.5+2, lengthwise)
Room for 20-22 panels south facing, full sun
Full detached garage available facing east/west, almost full sun. Est. 40 panels (future)
Plan to have 1 electric car/truck/suv, and one electric motorcycle in the next 1-10 years, with an additional car/truck/suv close or after. Currently we both work from home, 2 dogs, no kids, lots of tech, lots of hobbies.
Electric stove, clothes dryer, 2 12kbtu inverter mini splits, and a 3ton 2 stage A/C. Hot water heater and furnace are both natural gas.
All our home lights are LED, the main draws are home theater, microwave, NAS/gaming PC, other 110V cooking implements.
I also have a shop with all 110V air compressor, welder, 1/2hp lathe, 1/3hp mill, 1hp grinder, etc. Nothing essential, but information to have.

Goals:
1) Offset grid cost. All the installers focus on a $0 bill right now, which is not one of my goals and really puts me off the installers. Price is rising, usage is rising, I'd like to get something in place that can grow with us and be financially feasible.
2) Expandability - more PV, more battery, more inverting power. I don't want to be stuck down the road.
3) Provide at least some UPS / grid down functionality. Longest we've been without power was 30 hours in the last 10 years, but it gives me unnecessary stress.

The lobbyists won, so net metering here is dead. No choice other than zero export. Average current usage is ~1800kwh/mo. We will never be off-grid here.

I'm a DIYer, so an off the shelf solution or paying for full install is off the table. For this area and potential benefit, the cost is just too high. The best plan I've come up with so far is (and I'll try to make this make any sense) - Keeping the main grid feed to the 200A panel along with the dryer, stove, and main A/C. I consider these very power hungry and not completely necessary. 60A breaker off the main panel would feed an Outback Power Skybox. Additional 60A would backfeed an interlocked subpanel (see below). The Skybox seems to integrate all the functions I'm looking for and are outdoor rated to save space in the garage. ~8kw PV on the attached south facing garage would feed into the Skybox. That would then feed a subpanel in the house that houses all my loads (except dryer, stove, and 3ton A/C). That panel would have an interlock and be backfed from the 60A breaker mentioned above for the option to switch back to grid if necessary. I can't put all my eggs in the inverter's basket. Battery for the Skybox would be a server rack style 100AH 48V Battery, planning on starting with 2 with the option to expand this bank. The Skybox has CT's that can monitor the mains to insure zero export. My hope is that I won't need an additional skybox for my loads, but if I do, I'll just move the necessary circuits back over to the grid connected box until I get the future skybox installed.

Future:
After electric vehicle adoption.... Add however many panels I can fit on the detached garage both watts and space wise, and add another Skybox in parallel with another 2+ battery bank in the detached garage. The Skyboxes communicate with each other and the consumption monitor to adjust the output to maintain zero export. Another major benefit to using the Skyboxes is if the dumb laws here ever change, they can be reconfigured for net metering.

I antagonize over everything, something this substantial is a lot. Would love constructive opinions on what I missed / haven't thought of / found. Thanks!
Just curious. What state are you from where the lobbyist won?
 
Commercial Power Banks (either powerwall or blocks) with UL/CSA/ETL certification will obviously cost more but that also helps with Insurance Companies, many are quite stupid around solar systems but with a proper electrical inspection they can be "soothed" mostly. Before choosing your path, check with your Insurance Provider about what they need / want.

You are not looking at anything crazy from what you have posted. Complex & Involved maybe but not crazy. It is all quite doable but that also depends on Wallet Depth as to how fast & what level you want. By "Level" I mean grade of gear such as Tier-1 Victron or Tier-2 like Growatt or Value Grade (don't think about insurance) products.

LFP is by far the safest of the Lithium Chemistries today. It is NOT hard to build/assemble a good quality battery pack with proper components from reliable suppliers. For your system, without a doubt 48V Battery Banks are what is called for. 48V@250A (DC) can deliver 12,000W or 50A@240VAC. And yes, you absolutely want 240VAC System, especially if EV Charging is in the plan. NB: The newer models coming are coming with V2G, V2H and even V2V capabilities and so many things will shift within the next 5 years.

An Example to BUILD a 48V/304AH/15,564.8 (15.5kWh) can deliver 304A @ 48VDC for one hour and take 152A for two hours to charge.
16 pcs EVE 304AH LiFePO4 (LFP) 3.2V Cells Battery (Fully Matched&Batched)--Genuine Grade A : US$ 2,192.00 +S&H
1 pc JK-BMS [24S 2A 200A BT] (2s-24S BMS with 2A Active Balancer, BlueTooth UI with options US$ 177.08 +S&H
1 pc Fuse (Eaton/Bussman MRBF 300A) US$ 35.00
1 Case/Box to install it all into.

ALSO Look at this list of Commercial Packs which are in circulation. NOTE not all are availabe in North America but this is a good cross section of currently available... Actually it's out of date as several products from Known Companies have recently entered into the market. https://www.cleanenergyreviews.info/battery-storage-comparison-chart

SOMETHING Many are NOT Aware of here... Growatt makes a LOT of different solar gear, they also make LFP Battery Packs which directly integrate with their AIO's "All In Ones" but it is not unique to them. Even good "Value Gear" companies like Sigineer & Yiyen have prebuild battery systems that integrate. There are BMS' (Battery Management Systems) that we as DIY'ers can buy which integrate with AIO's, while they do cost a bit more the benefits warrant it.

Hope it helps, Good Luck
 
Just curious. What state are you from where the lobbyist won?
Indiana. Full net metering ended with installs in 2017. Installs until 1/1/2022 are on a 10 year grandfathered net metering, but after that are subject to sellback. Didn't really make sense to be screwed right at your breakeven point. Anything after 1/1/2022 has none. You get reimbursed at wholesale rate, not what you pay which makes it not financially feasible. I can't imagine we'll have any installers going door to door after the 1st.
 
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