My Solar PV Thread

[redpoint5]

EDIT: Link to the stats on my solar system.


I'm starting a thread here since Saving @ Home doesn't get much attention.

Some Oregon utilities have enticing subsidies for people that meet income criteria. My parents do, so I signed them up with the program to explore PV options.

Tomorrow a PV outfit is stopping by to evaluate the site and bid the project. I'll get at least 2 more bids before moving forward with any of them. The utility subsidy is a direct reduction in upfront price because they fund the installer directly. Then there's a 26% federal tax credit. My parents need a new roof, so a portion of that cost can be offset by the tax credit.

I've not been following PV technology lately, so any advice is appreciated. All I know is we probably want micro-inverters. I'd also like the system a little overbuilt since I'm also looking to get them a used EV.

If all that pencils out well and goes smoothly enough, I'll consider solar for my house. The utility offers higher income households a reduced subsidy, and that stacks with the federal tax credit. I'll need a new roof in 5 years, so rolling that into the install makes sense. That got me to thinking about Tesla's v3 Solarglass.

https://www.tesla.com/solarglass/design

It probably doesn't pencil out well financially, but it could come close. If the roof is capable of outliving an asphalt shingle roof, I'd be willing to pay a bit more. I hate asphalt shingle.

[oil pan 4]

I can literally build or reactivate fully functional RPG7 and have it be 100% legal easier than I can build and install my own solar power generation.

Micro inverters are dumb. They're fine if you have trees you can't cut down or are spending other people's money.
If you have a good location micros are a waste of money.

If you want to do it cheap get big used poly crystal panels no one wants. Hint, they will be too big for micro inverters.
Get a used inverter with some warranty left.

Watch out for installers running up the bill, this is the one thing they are really good at.

[redpoint5]

The appeal of micro inverters is mix/match procured panels as you mention, and expanding later on. Not sure what the price premium of micro is vs series, but I'd pay a small premium for the ease in expanding/modifying the system later on, and the extra data I could nerd over.

[oil pan 4]

Originally Posted by redpoint5

The appeal of micro inverters is mix/match procured panels as you mention, and expanding later on. Not sure what the price premium of micro is vs series, but I'd pay a small premium for the ease in expanding/modifying the system later on, and the extra data I could nerd over.

Oh no if you get used panels, buy them by the pallet, all the same, plus 1 or 2 extra.
It's a big difference. Micro inverters can easily cost 2 to 3 times that of a string inverter.

I would use micro inverters, if my panels were small enough, but let's say I had rood for 12 panels, but 10 puts me at the voltage limit for the inverter and stick those last 2 on micros, or I get a few panels on the edge of the array that get shade.

The best money in used inverters is 3 to 4kw that because those are super common and if you have to have it shipped most 4kw inverters are under the freight weight limit.

[redpoint5]

Well, first bid is complete. They quoted a much larger system than I had originally expected. 10.4 kW 30 panel system (Hanwha duo g5 325 Mono). I asked why not poly, and he said the cost savings aren't there and hardly anyone makes them. AP System YC600 dual microinverter x15.

$31,558 gross cost parts and labor = $3.03 per installed watt.

1. Pretty much needs to be ground mount because permitting on a manufactured home is a 60/40 gamble. That adds $0.30 - $0.40 per kWh, or about 12%.

2. Oregon law precludes series inverters if solar is installed on a habitable structure. That means this contractor has only been installing micros and optimizers, so the quoted cost was for one of those even though a series inverter is acceptable on a ground mount. I didn't follow his logic on that...

3. Array would be approximately 50 feet by 10 feet and a line trenched about 150ft to the house.

Should qualify for $14,000 in upfront incentives or a total bill of $17,558. = $1.69 net cost. Federal tax credit of 26% should bring that down to $12,993, or $1.25 net cost.

[oil pan 4]

You generally want mono, they're more efficient.
When you factor in shipping, racking, weight, available roof area.
But if you have unlimited room for panels go cheap.
I got really big used 295w polys that no one wanted.

Yeah you don't want want to put thousands of pounds on a mobile home roof. My little starter roof top 3.6kw weighs about 900lb the main roof support is a 6 inch I beam.

[redpoint5]

Originally Posted by oil pan 4

Yeah you don't want want to put thousands of pounds on a mobile home roof. My little starter roof top 3.6kw weighs about 900lb the main roof support is a 6 inch I beam.

I'm ok with ground mount. The roof has a shallow pitch and my dad angled the house away from true south. It will be easy to adjust pitch and clean the panels this way, plus they should stay cooler/more efficient.

Curious what your cost per watt ended up being, your own labor excluded?

Tesla's website is estimating a much lower cost compared to the quote above. $25k for an 11.4kW system before any incentives. Of course, that probably assumes roof mount and optimal engineering to fit it all. Maybe I'll get a quote from them too.

https://www.tesla.com/energy/design

[oil pan 4]

Running total is about 70 cents a watt.
But that's big polys no one wants, used inverter, racking on galvanized steel unistrut which may not be an option for places where it rains a lot.
Wire and emt came from my huge collection, it would have run around 10 cents a watt if I had bought it retail.

[redpoint5]

My parents qualify for an extra $5k that I wouldn't, so it makes contracting out the work more appealing, especially since it will have a warranty.

[oil pan 4]

It's hard to find used panels with a warranty but easy to find a used inverter with a few years left.