What to build now to get 30% Solar Tax Credit?

[PatBlack]

Sorry this is long but if I don’t put in the details now, I’d just get asked to provide the details later!

I am seeking guidance on what I might think about installing before year-end to take advantage of the 30% solar tax credit.

My current situation:
My house is 2800 sq ft, on the grid with a 100Amp service. I use an average of 190 kWh monthly, ranging from 120 to 300 kWh usage depending on the month. Rural property with great solar exposure, so plenty of room to panel up on a ground mount system. Grid is very unreliable with outages of 2 – 6 hours several times a year. My county’s electric grid is going to be 100% daytime solar electric by 2022. Not sure how they define daytime! Nighttime, it’s coal-fired electric. (Yeah I know, that coal plant is really going 24/7.)

Reasons:
My purpose for installing a system is practical, educational, and ecological. I’d like some power during outages, I like to learn new things, and if I can save a few train car loads of coal from being burned, I’d like to do it.

Do It For Me System:
In 2017 I got a quote from the local PV installer for a grid-tie ground-mount 2.85 kW PV system installed for $13,000. That was spec’d as 10 Suniva OPT285-60-4-1B0 panels and a SMA America SB3.0-1SP-US-40 Inverter. I did not move forward with that. I could get an updated quote, but I imagine they would still want to charge me some overly large amount of cash.

Experience:
I don’t have much experience with solar systems. Willing to learn. Just to gain some practical experience I got one of those harbor freight 100 watt kits, plus a 35 Ah battery and a 1500 watt modified sine wave inverter. I learned a lot and still use it to charge devices and run some lights. I swapped out the battery and the charge controller and now I have 2 100-Ah Battle Born batteries and a Victron MPPT 100/30. Those parts are supposed to be part of a future van build project, but can be repurposed temporarily if desired. Tried to replace the panels with a single 315 watt Canadian Solar panel from those local installers, but their quote was 30% higher than any online price.

Possibilities:
I am intrigued by hybrid grid tie possibilities so that I could run some loads during an outage. (Refrigerator, some lights, wireless internet and a WiFi router.) I imagine at some point in the future I’ll be driving a 4WD electric pickup truck, so something expandable in the future seems prudent.
I looked at Will’s videos about the MPP solar inverters. I quickly got confused on MPP’s website as to which model would be appropriate for me. I didn’t see how I’d wire that up to more than a couple appliances on a power strip. Could I put a few circuits into a critical loads panel and put the solar inverter between the main panel and the sub panel? I have a local electrician who can do the standard stuff but I doubt he has any solar experience at all.

Any other ideas of a useful solar project that I could build and have the Feds pay 30%? I would appreciate any suggestions on what’s useful and feasible to install / get installed by year-end.

Kudos if you’ve read this far! Thanks for any ideas I should consider. I need to decide a direction quickly.

 

[svetz]

Welcome to the forums PatBlack!

Good job saying no to that installer, $4.56/w sounds ridiculous. See What should you pay for a Solar Installation?

Don't fret too much about losing on the 30% rebate, if you fall into next year it's still 26% in the states. Also check your state, many offer incentives of some type (e.g., Florida doesn't charge sales tax on it).

Sounds like you learned a lot from your starter kit! But, check out the FAQ, there are a few other topics in there that might interest you.

So, here's some quick math based on your post. I know your intent is to learn, more power reliability, and being a friend to the environment.

Power Needed
The good news is you don't use a whole of power, the bad news is there's a big swing to it. So, you have to make some choices. But let's look at what it takes for the whole 300 kWh (just change the numbers to whatever you think is best for you).

300 kWh/ month / 30d/month = 10 kWh / d that you consume on average. But the real question is when do you that power? If it's mostly in the evening then you'd need batteries to cover most of it. If it's mostly during the day you might not need a lot of battery to get you through the night. See the FAQ for tips on figuring that out.

In terms of how many panels you need, you first need to know your insolation number which you can get from an insolation map. That number represents the average amount of solar power per day you can get at 1000 W/m2; very useful as that's how solar panels are rated. I know that sounds weird, but as you'll see from perusing the FAQ you might only possibly see 1000 W/m2 at noon for a few minutes, after that it's all downhill as the sun's angle takes it through more of the Earth's atmosphere absorbing that energy.

Anyway, let's say your insolation number is 5. So, let's assume 20% losses on average in wire, dust, and equipment efficiencies and we get

10 kWh/d / 5 / .8 = 2.5 kW array. With 315W panels that would be 2500 / 315 = 8 panels.​

Other Stuff
There's more examples in the FAQ to figure out how many many batteries and such you'll need. Also check out the forums to see where members are buying their gear and what they buying and why.

If you get stumped on something just ask, there are a lot of different forums but hopefully you'll be able to find the best.

 

[PatBlack]

Thanks Svetz for your kind reply. Can I suggest that FAQ be a top-level forum category? The forum search engine does not allow a 3-character search term. That restriction bit me before, when I was trying to find a thread on the MPP solar inverters. Maybe that search restriction could also be changed? I did find the FAQ after a while.

I looked at the insolation map you suggested and am fortunate to be in an area with a number of 5.5 or 6. So your math was pretty spot on!

The FAQs will certainly come in handy when I get into the details of designing something that fits my goals. Right now I am still in the high level thinking about *what* I should build. The only local installers are working on megawatt arrays right now. We'll see if I even get a call back for my relatively tiny needs. Net metering may or may not be allowed anymore with my utility provider. I pay about 25 cents a kWh. I need backup when grid is down. Right now I just fire up a generator and run extension cords, very inconvenient.

You mentioned in another thread the Sol-Ark in limited home mode, sounds interesting. Zero-out the home use as much as possible in the day, charge a battery bank, dump the excess power to something useful, run from battery bank and/or grid at night and on the cloudy days. My goal to have the system be expandable gets me thinking about micro-inverters. I know I can build a nice ground mount racking system out of steel components. I can install and wire panels. I can wire a battery bank. Choosing the right inverter is going to be a lot of research. Then I need an electrician to get that installed. I think that's beyond my skill set.

 

[svetz]

Hey PatBlack!

Can I suggest that FAQ be a top-level forum category? The forum search engine does not allow a 3-character search term. That restriction bit me before, when I was trying to find a thread on the MPP solar inverters. Maybe that search restriction could also be changed? I did find the FAQ after a while.

I'm a retired moderator (see Retirement Party!) They're just a bit undermanned and haven't gotten around to fixing the title. But I do like that idea, you should post that it in the forum for improving the forums.

I looked at the insolation map you suggested and am fortunate to be in an area with a number of 5.5 or 6. So your math was pretty spot on!

Those maps are amazing!

I pay about 25 cents a kWh. I need backup when grid is down. Right now I just fire up a generator and run extension cords, very inconvenient.

Holy Toledo that's pricey!

For the outages, what you need to ask yourself is how much power do you really need and for how long. You might check into the thread Solar Generator and Micro Systems. My favorite of course is the cheap-but-immediate-gratification-with-a-future-DIY-LiFePO4-Battery-option: Budget Models with Amazing Future Power; some DIY required.

My goal to have the system be expandable gets me thinking about micro-inverters. I know I can build a nice ground mount racking system out of steel components. I can install and wire panels. I can wire a battery bank.

Lots of members here who have been there and done that and more than happy to share tips.

Choosing the right inverter is going to be a lot of research. Then I need an electrician to get that installed. I think that's beyond my skill set.

Hiring an electrician for the dangerous bits is always a good idea.
Microinverters are the ultimate for expansion, no pesky matching of panels for string voltages and currents or working with set size limits or worrying about mismatch due to age. Plus a 25 year warranty. If you're not sure what the future brings, they're the way to go. The IQ8 that will support being grid-tied and battery power should be out soon; but the Tesla powerwall already works with most microinverters and they're fairly cost competitive (well, not as much with DIY or some of the new low-cost lithium batteries that have recently come onto the market). You might find this of interest too: Incrementally Adding AC Batteries

 

[bulrush]

Solar power market research, costs, and incentives for US states are here. https://www.energysage.com/solar-panels/solar-rebates-incentives/ia/

This might help.

 

[PatBlack]

Thanks @bulrush looks like $3 - 4 a watt for an installed system in my state.

 

[Bigbillsd]

I had asked about a back-feed system in another post yesterday. And this morning a friend sent me this link. https://legionsolar.com/index.html

There is a way to charge batteries too, but their solution appears very limited. I guess you could always run a charger from the 120v side on a timer and make a larger battery bank if that is actually a requirement. My 4 @ GC2 260ah batteries will run my 40' motorhome for a long time while drycamping, including toaster, coffee pot, lights, radio, microwave and hair dryer. (aka boondocking) (I will be upgrading that to LiFePo4 this winter and maybe I just found a use for the GC2's I will be removing...)

The interesting part is there is no back-feeding the power company so no permits are required. I will be calling them on Monday to ask a few questions but this seems like a no brainier to lower my always on 600w of daytime consumption.

I cannot believe there is someone selling this. I thought I was going to have to modify a micro inverter to work, but had no idea how to prevent power from backfeeding the grid when I wasn't able to consume it all.

 

[PatBlack]

Yes I came across legion solar in my search. Look at the post in this thread to understand why I didn't pursue it.

https://diysolarforum.com/index.php?threads/legion-solar-4.680/

Also search for reviews on legion solar and plx devices. There's an old reddit thread which says this:

"They are a kickstarter project that basically sold themselves based on the fact that "you don't need permission from your utility or city" to install.

None of that is legit at all.

They literally have a document about "what happens when someone when someone finds out I illegally installed solar" (link removed because automod dont like). With helpful hits like "I do not consent to a search of this premises". They also go on to explain that equipment only needs to be UL certified (which Legion products are not) if you are doing a legal installation by the books, and since this isn't one of those, you don't need to worry about it. Never mind the fact you just completely invalidated your homeowners insurance.

They also say that you don't need any city permits either because you're not paying a contractor to install it."