Optimistic solar breakeven calculation

My drive for solar started with just battery backup for wifes cpap machine. Then I thought how do I recharge them if something happens to the grid? So here comes solar. Then what about heating and cooling the house. And it just spirals up from there. Whole hog or none.

I'm tied to my current home for at least the next 15 years - so that was my initial payback period.
Everything is a hedge against the future and increasing my own homes resiliency.

My electric use will never go down. More devices always coming in AND we now has an EV.
Electric cost will never go down. Any upticks in utility rates only makes my payback better.
We wanted a generator for grid loss. So I took that money and put it towards batteries.

We had a >5 year old roof, good southern exposure, and a healthy line of credit. Yes, I paid someone to install the panels [to get the extended manufacturer warranty] and the rest of the system is warranted beyond or to that 15 year payback (except the batteries).

So far, even with her nightly charges, we've pushed our bill to nearly zero on usage and are only paying the ridiculous fees that the utility levies. But that was during the low solar months at the beginning of the year and I'm expecting to get those wiped over the summer when we are exporting enough to hit the export limit/payback limit from the utility.

If all stays as is and the system performs to the same levels is have over the past 6 months - we will be in a single digit year payback scenario. Sure, that's still a long time to most people who want sub-5yrs or nothing, but I'm comfortable knowing that even in a prolonged grid loss - all I need is a mildly sunny day to maintain my life and my home.

I've even got about 600gal of rainwater collection and a solar battery/pump for the drip system in my garden out back. Watching the costs of everything rise and I'm just sitting over here bringing in some tomatoes, lettuce, and dewberries to supplement my dinner last night while cooking on the stored battery PV power.

45North said:

Many calcs of breakeven fail to include the "opportunity" cost of capital. This means:

• Loan interest charges, if you are borrowing the money, or
• Alternative Income earned, if you have the cash and invest it elsewhere
• Throw in the extra cost of managing, building and operating your own power company

All these things will lengthen your breakeven time and reduce the attractiveness of your DIY solar project.
If you know this and still want to do it anyways, that's fine but you should recognize that it's more of a hobby project and not really a pure investment decision.
Sorry to rain on your parade, but let's be realistic here.

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I could have installed a whole house gas generator instead. When does a gas generator pay for itself?

I should add, last month I had the lowest electric bill I can remember ever in the 20+ years I have lived in this house.

$25,000 to run juice to the place. Saving money with solar. Maybe. So far….

Looking to help friends in the Philippines with solar, their electric bill for 10 kWh per day is about 52 US dollars per month. Batteries are horrendously expensive still, they are looking at 140 US dollars for EVE 280AH cells, but I suspect they will come down. A battery would be about 3000 including wiring, housing and BMS. An all in one charger/inverter and solar panels should cost about 2500, add inspection fees and the system should cost less than 6000 US complete, at today's prices. Payback would be around 10 years, about the time the batteries are expected to last.

I am not calculating investment opportunities, inflation, or generator running costs during brownouts, in summer where temperatures can go up to 40C, they do need a reliable system. I am not even looking at a reduced carbon footprint or reduced air pollution, which for some is also a motivation.

I am not sure if the batteries and inverter could cope in a shaded shed in that heat, or would they need some form of cooling, if so this would be an added cost. Nor am I sure how much the inspection fees would be, but I will leave that up to them.

New nuke in Georgia is looking hopeful at 80 year payback. Good luck.

“Hopefully, despite being seven years late and billions over budget, the two new units at Plant Vogtle will finally perform well for at least the next 80 years to justify the excessive cost,” said Liz Coyle, executive director of Georgia Watch, a consumer group that fought to limit rate increases.

https://finance.yahoo.com/news/second-nuclear-reactor-completed-georgia-155053005.html

45North said:

Many calcs of breakeven fail to include the "opportunity" cost of capital. This means:

• Loan interest charges, if you are borrowing the money, or
• Alternative Income earned, if you have the cash and invest it elsewhere
• Throw in the extra cost of managing, building and operating your own power company

All these things will lengthen your breakeven time and reduce the attractiveness of your DIY solar project.
If you know this and still want to do it anyways, that's fine but you should recognize that it's more of a hobby project and not really a pure investment decision.
Sorry to rain on your parade, but let's be realistic here.

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I agree that many calcs don't include the opportunity costs, which runs both ways.
One needs to also count the tax rebate + earnings on it and the earnings on the yearly savings.

Lots of good points brought up here.
For me, the world is going nutz, the more stability I can offer my wife and I the happier we both are. ROI doesn't really matter as much as peace of mind.

so, to sum it up, this is our hobby and we just need to figure out how to justify the time and money spent.

aragonx said:

I love your 2nd point. What price can you put on having some peace of mind?

Your third point is also a very strong one. Most server admins I know have backups and redundancy. It never occurred to me until just now that there is a single power option without some sort of self generation. So the grid is a single point of failure. That term alone is enough to make many server admins lay awake at night with worry.

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Something not mentioned is how long will this crap equipment last. From someone who just had to return 2 defective inverters after 3 months of use, I doubt 10 years, even for the more expensive ones. Never heard the word replacement of equipment. Just make sure you have a way to pay for more stuff in the future! Piece of mind is my reason also. Grids coming down eventually!

Your assertions are on point, but there are other intangible factors.

Same logic applies to paying off your house vs keeping a mortgage and investing instead. As long as rate of return is greater than interest, you are ahead.

But I paid off my mortgage, because nothing can happen to my income that will cause me to lose my home.

I also installed solar, so that when I am retired, I will not have an electric bill.