Residential solar power questions
March 31, 2017 1:44 PM   Subscribe

We're considering installing solar panels on our house. I'd like to learn about the pros and cons of different equipment types, financing, and installers.

We've started to get quotes for installation of solar panels on our house (for a net metered system). To evaluate the quotes, I'd like to learn more about the different types of panels and inverters - what are the pros and cons of each? Where is good to learn about this?

There are multiple financing options, from cash purchase to loans to leases. How did you choose between them?

Installers seem to range from small local companies to big national ones. How do I evaluate that? If there are MeFites with installer experiences or recommendations in the front range of Colorado, I'd be happy to hear about that as well.

I've read the previous questions, but most are from a few years ago.
posted by medusa to Home & Garden (5 answers total) 12 users marked this as a favorite
The Sweethome's solar power guide is a good starting point. It covers most of your questions.

Solar Panel Talk is a much deeper dive and filled with Strong Opinions but you'll learn a bunch trawling through the forums.
posted by llin at 1:57 PM on March 31, 2017

If you can wait a bit, SolarCity/Tesla's new roofing options look amazing. There's the added benefit that you won't need to repair/replace your existing roof before installing a panel system, or have to remove a panel system to do roof repair/replacement in the future. Not that much of a bonus if you already have a new roof, though.

2nding the Sweethome guide. Also check DSIRE, which is a database of local energy incentive/rebates to see if there's any programs to offset your cost.
posted by givennamesurname at 2:09 PM on March 31, 2017 [2 favorites]

I live in Colorado and had solar installed 2+ years ago. I also have a degree in electrical engineering and dad was an electrician.

You don't say where you are but I assume you've got Xcel. If that is the case, you'll almost certainly want to own the system (cash or loan) instead of lease. I've known some house sales to fall through because the buyer couldn't qualify for both the mortgage and the lease. There are other issues, too. My loan was 4% for 7 years and basically amounted to what my electric bill was - so it wasn't a huge expense. If you're on one of the co-ops, the lease deals may be better - I don't know.

I think Xcel still has two programs you can subscribe to - credits or cash. The credits accumulate during high output (summer) and you can use them during low (winter) output. But, they aren't transferable, and if you make more than you use year after year, you basically lose the credits. With the cash option, they buy the excess for 2-3cents per KWh and you either get a reduction on your bill or they send you a check.

In my case, I opted for the cash - I get 5-20 dollars per month for my excess capacity over and above a total offset of my electric bill. But, I have gas appliances (dryer, water heater, furnace, stove) and a really great unshaded south facing site. So my production roughly tracks and exceeds my consumption throughout the year - I could theoretically, with a battery system, cut out the grid entirely. If your site isn't so good and you have electric heat/appliances, the credits may make more sense because your consumption will be much higher in winter than in summer.

Xcel also makes it hard to upgrade later - so you'll want to size it for as much output as is practical. The largest you can go is 133% of your highest month - if you just bought your house, they have a square footage calculator they use in lieu of past bills. The actual size of your array is going to depend on how good your site is - my array is 1/2 the size of my co-workers for the same output because my siting is better.

If you have all electric appliances (hot water, etc.) and lots of shade trees and bad facing, it might not make sense to install solar, yet.

There are two basic types of inverters - micro inverters that fit onto the panels themselves and the larger inverters that are sized according to the number of panels you have and are placed near the meter. Micro inverters are nice because if a panel is shaded (say snow or something), or something else occurs, the other panels can still produce. Upgrading the system is also easy - just add more panels/inverters. The downside is that they are a bit more costly, somewhat less efficient, and if you have 20 of them, the odds of one failing are higher. The single inverters are sized to the array, and upgrading may require replacing an expensive inverter. They can be slightly more efficient, but if something breaks your whole array is offline.

We used Atlasta Solar - a small local company and have been well served. I like that I can call and talk to the owner, and get really great service. You should collect a few quotes from different places and the arrays should be within the same ballpark of each other. There will be variability based on how you estimate various factors (facing, shading, consumption, etc.) but the salespeeps should explain the model and assumptions they use - the math isn't hard so don't be intimidated.
posted by Pogo_Fuzzybutt at 3:56 PM on March 31, 2017 [4 favorites]

I just had a 3.99 kWh solar system installed over the winter. I used EnergySage to evaluate different quotes from installers - the one I chose included detailed break-even/ROI forecasting for different financing options. Loads of resources. I ended up getting a solar loan for $0 down/3.25%. Should pay for itself in 2 years, assuming my state continues the SREC program.
posted by acridrabbit at 5:00 PM on April 1, 2017

If you don't have a steeply-pitched roof, snow accumulation may affect your energy production. My roof is fairly shallow, and snow loads don't slide off the panels as readily as on some other roofs. This has caused me to lose production for up to a month when it's a particularly cold and snowy winter. As of right now, I'm running a net positive balance with the power company. This is in MA, where the credits don't expire. Colorado looks to have an unusual SREC program (maybe only for community systems), which you should make sure you understand. It can make a big financial difference.
posted by Kirth Gerson at 6:25 AM on April 2, 2017

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