New to solar, basic idea for DIY Grid-Tie

[kscessnadriver]

New to the solar game, just started doing research within the last few weeks. I live in rural NE Indiana, on acreage, so I'm looking into a ground mount array, probably feeding into a string inverter (most likely multiple Growatt of some size). The local PoCo is a co-op, which publishes their agreements for solar on their website. Currently they bill grid tie systems a flat $57.50 monthly fixed charge, and charge $0.0764 per kWh, or pay the same back per kWh. Household average kWh/month for the last year is around 1750 kWh, as everything in the house is electric. Obviously winter usage is way, way higher than summer, but the single largest month is in the neighborhood of 2500 kWh.

I'm thinking about using used panels of some sort, and building a ground mount in the 12-15 kW range, which would be roughly 250 ft away from the house at the closest. Current electrical service is on a 200A Siemens panel, 40 slot, that unfortunately is full. Obviously I'm going to have to either upgrade the panel, which brings up options. I'm leaning towards making my current panel (which is the service panel) a sub panel, and installing a smaller panel next to it to become the service panel. Something like a 12 slot 225A main panel, which then would feed the current 40 slot panel, and I'd probably move my barn feed onto the new panel. Obviously putting in a 225A panel, with a 175A main breaker, gives me 76A to backfeed. Does this sound like a decent idea, or would I be better off just replacing the whole main panel?

In terms of ground mounts, I'm looking to DIY something, so I'm considering either ReadyRack or Sinclair, both are fairly close to me, so I'd be able to presumably go get them from the manufacture. Or are there better suggestions I'm not seeing. I've seen IronRidge, I'm just not convinced they're cheaper than either of the previously mentioned.

Used panels, any reason to avoid frameless panels? Any reason to get frameless panels?

Just trying to hear myself out almost, any ideas I'm missing?

 

[BryceFreeman]

any reason to avoid frameless panels?

Frameless panels like flexible panel or trickle charger panel are usually used on car or RV. For house solar, frame panel will be better since aluminium frame is strong and solid. That's my opinion. Not good to choose frameless panels for household solar system.

 

[Hedges]

At $0.0764 per kWh, hardly worth investing in PV at all.
I've generally put cost of GT PV hardware at $1/W (no RSD needed when not on house), which amortizes out to $0.025/kWh over 20 years. "Amortizes", as in I'm not including time value, interest rates.

We are seeing cheaper panels lately; bunch of us bought new panels for less than $0.20/W. And the GroWatts you're considering are probably cheaper than my Sunny Boys (but I don't know if they're more likely to fail in that time.) So maybe you can get down to $0.020 or $0.015/kWh. Mounting hardware does start to dominate cost, so scrounging and DIY could save more.

Consider whether it is worth your time to save a nickel per kWh. And give up return on your money (as well as return of your money.)

Net metering terms may change in the future.

As for panels, there are a ton of framed panels out there, and mounting systems. Stick with what is mainstream, and mass market plus used market makes it cheapest.

Mounts, I'm mostly using Unirac.

Electrical panels, I use a 200A main breaker only and Polaris to fan out to multiple breaker panels and PV disconnect. No 120% rule this way. I have a 100A fused disconnect for PV.

225A busbar panel with 200A main breaker allows 70A PV breaker, 56A continuous.
With 175A main breaker, 95A PV breaker, 76A continuous (as you note.)
Either is about enough for 13kW PV, producing about enough year-round with net metering to supply your year-round consumption (but check and insolation website for your location).

 

[kscessnadriver]

Frameless panels like flexible panel or trickle charger panel are usually used on car or RV. For house solar, frame panel will be better since aluminium frame is strong and solid. That's my opinion. Not good to choose frameless panels for household solar system.

I was thinking something along the lines of a Stion panel, something like an STL-145. Frameless glass panel, 26.5"x64". There's a few place I see them listed for sale, but they've been for sale for quite a period of time. Not sure if there's a deal to be had.

 

[Hedges]

What prices?
How do they compare to this:

Do Business Better with Inxeption

Inxeption is the leading technology platform digitizing the global Industrial Commerce value chain. We are advocates for our ecosystem of suppliers and buyers, enabling them to do business better.

inxeption.com

 

[kscessnadriver]

At $0.0764 per kWh, hardly worth investing in PV at all.
I've generally put cost of GT PV hardware at $1/W (no RSD needed when not on house), which amortizes out to $0.025/kWh over 20 years. "Amortizes", as in I'm not including time value, interest rates.

We are seeing cheaper panels lately; bunch of us bought new panels for less than $0.20/W. And the GroWatts you're considering are probably cheaper than my Sunny Boys (but I don't know if they're more likely to fail in that time.) So maybe you can get down to $0.020 or $0.015/kWh. Mounting hardware does start to dominate cost, so scrounging and DIY could save more.

Consider whether it is worth your time to save a nickel per kWh. And give up return on your money (as well as return of your money.)

Net metering terms may change in the future.

As for panels, there are a ton of framed panels out there, and mounting systems. Stick with what is mainstream, and mass market plus used market makes it cheapest.

Mounts, I'm mostly using Unirac.

Electrical panels, I use a 200A main breaker only and Polaris to fan out to multiple breaker panels and PV disconnect. No 120% rule this way. I have a 100A fused disconnect for PV.

225A busbar panel with 200A main breaker allows 70A PV breaker, 56A continuous.
With 175A main breaker, 95A PV breaker, 76A continuous (as you note.)
Either is about enough for 13kW PV, producing about enough year-round with net metering to supply your year-round consumption (but check and insolation website for your location).

Solid info, thanks for looking at it. My thought was to start with something that more or less covers my power usage, and see how it goes. Perhaps a year or two down the road, add more if I could find the right deal. PoCo allows for residential production beyond normal usage, up to 50kW, before you become a "commercial producer" and the terms of the deal change.

I love the look of the frameless panels, like Stion, but the math just doesn't work out for how much they want for the panels used. The idea of just putting in a 200A main breaker only panel might make sense, especially if down the road I might want to add on to the production capability. I'm familiar with the Polaris connectors, having used them in a generator hookup to the house recently. Adding a main breaker only prior to the current service panel wouldn't be too difficult.

 

[kscessnadriver]

What prices?
How do they compare to this:

Do Business Better with Inxeption

Inxeption is the leading technology platform digitizing the global Industrial Commerce value chain. We are advocates for our ecosystem of suppliers and buyers, enabling them to do business better.

inxeption.com

The Stion panels I've seen are STL-145, 145 watt panels, that they want $50/panel for. They're generally listed as "make offer" as well, but I get the feeling they're not willing to budge much on price.

 

[Hedges]

Do you get power outages?
A backup system may give you value, that trying to save off the nation's cheapest electric rates does not.

Could still be a Growatt system, or Sol Ark, SMA, many other options.

$0.22/W vs. $0.36/W is pretty much a no-brainer, unless there are quality differences.
More deals may show up in the teens. We got 370W panels for about $0.19 including delivery and California sales tax. Larger panels aren't quite as cheap.

Of course you get federal tax credit.

When someone advertises used or liquidating inventory, I often ask, "how much for all" and get a deal.

 

[kscessnadriver]

Do you get power outages?
A backup system may give you value, that trying to save off the nation's cheapest electric rates does not.

Could still be a Growatt system, or Sol Ark, SMA, many other options.

$0.22/W vs. $0.36/W is pretty much a no-brainer, unless there are quality differences.
More deals may show up in the teens. We got 370W panels for about $0.19 including delivery and California sales tax. Larger panels aren't quite as cheap.

Of course you get federal tax credit.

When someone advertises used or liquidating inventory, I often ask, "how much for all" and get a deal.

Not frequent power outages, but I've got 2 multiquip diesel generators sitting here for that; A 14 kw single phase and a 40 kw single phase generator, with storage for 250+ gallons of diesel. I have less than zero intrest in a battery system. One of the biggest reasons I like the Stion panels I saw listed was the operating voltage is fairly high on them, while the amps are very low. Wire cost is probably going to be one of the largest costs, as I'm looking at probably a 300+ foot run back to the house, where I'd intend to put the inverters.

I don't want to post a link to said Stion panels, but if you search a large online auction site, they're listed there, if you search.

 

[kscessnadriver]

Also, to add and make clear, the $0.0764/kWh is only once I'd be running a grid-tie operation. Currently I pay $0.0948/kWh, so the math isn't quite as ugly, but it's still not great.

 

[1201]

A pallet of 30 new Canadian solar 390w panels is .305/watt as signature solar

And you can get 30% off of that if you pay taxes

 

[Hedges]

Looks like Growatt GT inverter tolerates 600 Voc, so the 300' run is no problem. Some brands like Fronius support up to 1000V.
I've found it most convenient to have separate 12 awg runs for every string, allowing for changes to inverter configuration later on.

145W, 79.6Voc, 2.38A Imp?

https://cdn.enfsolar.com/Product/pdf/Crystalline/58cf359da8079.pdf

Consider larger panels, in the 300W to 500W or so range, 7A to 12A. Less mounting cost. I have up to 370W, which I can swing around myself.
It is OK to have a couple or few percent voltage drop at peak output, even 10%. There is a trade-off between copper wire and PV panel cost.
Were you going to use 12 or 14 awg for < 2.5A? You can run higher current. If you really want you can use 10 awg for 10A panels, but you don't have to.

A way to get more use out of the copper is to parallel strings of different orientation, so their current peaks at different time of day.


As for batteries, I consider them a wear item and don't want to spend money there, but for at least critical loads backup it is nice to have silent power with no moving parts.


Still, consider where else you could invest your money and time for greater return. Build a rental unit? Some other investment?
If turn-key solar installation would be a money losing proposition, then cheaper due to DIY labor isn't so great.
My utility rates in San Jose are up to 6 times yours. Since I have net metering, PV it is worthwhile.

 

[kscessnadriver]

Looks like Growatt GT inverter tolerates 600 Voc, so the 300' run is no problem. Some brands like Fronius support up to 1000V.
I've found it most convenient to have separate 12 awg runs for every string, allowing for changes to inverter configuration later on.

145W, 79.6Voc, 2.38A Imp?

https://cdn.enfsolar.com/Product/pdf/Crystalline/58cf359da8079.pdf

Consider larger panels, in the 300W to 500W or so range, 7A to 12A. Less mounting cost. I have up to 370W, which I can swing around myself.
It is OK to have a couple or few percent voltage drop at peak output, even 10%. There is a trade-off between copper wire and PV panel cost.
Were you going to use 12 or 14 awg for < 2.5A? You can run higher current. If you really want you can use 10 awg for 10A panels, but you don't have to.

A way to get more use out of the copper is to parallel strings of different orientation, so their current peaks at different time of day.


As for batteries, I consider them a wear item and don't want to spend money there, but for at least critical loads backup it is nice to have silent power with no moving parts.


Still, consider where else you could invest your money and time for greater return. Build a rental unit? Some other investment?
If turn-key solar installation would be a money losing proposition, then cheaper due to DIY labor isn't so great.
My utility rates in San Jose are up to 6 times yours. Since I have net metering, PV it is worthwhile.

I figured I would run those particular Stion panels in a 6P4S configuration, combined in a box. Should get me somewhere around 366V & 9.5A, and keep me safe on the top end, and still be able to run in 12AWG wire. So basically 24 panels to get 3.4kW. Yes, it's a lot of panels, and yes it's a lot of racking. That's why I posted here, just to get some ideas on what route to go.

 

[1201]

I figured I would run those particular Stion panels in a 6P4S configuration, combined in a box. Should get me somewhere around 366V & 9.5A, and keep me safe on the top end, and still be able to run in 12AWG wire. So basically 24 panels to get 3.4kW. Yes, it's a lot of panels, and yes it's a lot of racking. That's why I posted here, just to get some ideas on what route to go.

24 panels for 3..4 kw? Ouch.

 

[kscessnadriver]

24 panels for 3..4 kw? Ouch.

145W a panel. Yeah, they're not real efficient, but they're not as bad as you think, as they're not the normal 39x65 dimension, only being 26x65. Still not great, but not as bad as it sounds.

 

[Hedges]

Lot of fuses, too. With more than 2 strings in parallel, all require fuses.

133W/m^2. You can get panels 200 to 220W/m^2, which saves a lot in mounting hardware.

The ideas we're offering you include getting larger, more efficient framed modules, connecting one or at most 2 PV strings to a home-run wire, feeding one or two strings to each MPPT input.

The inverter I'll be using next is SMA Sunny Boy Smart Energy, 7.7kW, 3 MPPT inputs for up to 15kW PV. (end of next year another model will be 11.5kW, 4 MPPT inputs up to 23kW PV.) Optional battery would be charged by PV over-paneling, otherwise production clipped during full sun.

If you have more than 2 PV strings per MPPT, run separate wires from each string to PV combiner box with fuses or breakers per string.

 

[1201]

145W a panel. Yeah, they're not real efficient, but they're not as bad as you think, as they're not the normal 39x65 dimension, only being 26x65. Still not great, but not as bad as it sounds.

The amount you spend mounting those will be significant and not worth it for the output.