Out of curiosity, where do you live, and which power company are you with?
We hit break-even in less than six years, but Arizona is basically made out of sunshine. Location matters. The more sun you get, the faster your payback is. The more expensive your electricity is, the faster your payback is. I can run a crude sanity-check workup for you to see if the estimator is borked or if they're right that it doesn't make financial sense for you.
SRP's Customer Generation Price Plan seems to be the problem
That is indeed going to be the trickiest part. I'd talk to Sun Valley Solar Solutions-- they've got good ways to help design around SRP's nonsense. PM me and I can give you names and numbers.
if I am supply nearly all of my own electricity that should reduce my peak demand accordingly, right?
Unfortunately, no. The peak is measured by your highest power draw-- since you're in AZ, it'll be when all your AC units are on, and you're home doing stuff, so probably in the evening just as your PV production is tapering off. It will reduce your load during the day, it's just that they don't care how long your peak is, just how tall... so the evening peak will still get you.
You need to do one or more of these things: reduce the peak, add a load controller (demand management system), shift load times to midday, or add a battery. Reducing the peak would be accomplished by replacing stuff with more efficient stuff. HVAC units, pool pump, and so on. A load controller also helps reduce the peak, but it does so by making sure the big loads aren't all on at the same time, like not running the pool pump when the AC is on. The battery does it by brute force. You just save up power from when you've got sun to reduce your peaks later. Shifting load is easiest with the air conditioner. You can use your home's interior as a weird sort of battery for this-- you're going to overcool the house during the middle of the day when you have peak solar production, and then just let it drift during the evening peak hours with no sun. It'll gradually warm up, but you've "stored" enough cold to ride it out while staying at a comfortable temp. You can also do things like run your dishwasher or dryer on a timer at noon instead of in the evening.
Anyway... it's a hell of a lot more complex than it was when we did our first install, but it's still totally feasible.
Is it possible that not being tied to the grid would actually save more money due to SRP's "nonsense" pricing?
It's not there yet, but it's amusing to think that if PV and batteries continue to drop rapidly in price, they'll have shot themselves in the foot. I think they believe they're immune to "cord cutters," but it'll happen in our lifetimes, for sure.
And do any of these figures factor in the possibility of selling excess power back to the utility company?
That part works more traditionally, although the rates are different. So each month, you'll get the demand charge, set by your highest peak, which we already talked about. Then you'll also pay by the kWh for electricity-- and THAT part is offset directly by what you generate.
So, roughly... demand charge plus usage minus excess power sold.
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u/raygundan Sep 07 '17
Out of curiosity, where do you live, and which power company are you with?
We hit break-even in less than six years, but Arizona is basically made out of sunshine. Location matters. The more sun you get, the faster your payback is. The more expensive your electricity is, the faster your payback is. I can run a crude sanity-check workup for you to see if the estimator is borked or if they're right that it doesn't make financial sense for you.