I'm submitting this in case anyone is contemplating having solar installed on their property. This is my almost one year experience. Everyone's situation would be unique. This is just ours.
Why did I install solar? I've had a couple of people ask me that and I had to think about it. Reasons might include saving money, going green, going off grid to screw the utility companies, prevention against unreasonable rate increases, or reducing foreign oil imports. I finally decided in my case it was 80% just wanting to move a step ahead in technology. It just made sense to me. The other 20% was to cut costs but that takes time.
It isn't easy computing the payback of a solar system. In the long run it may not have been a good thing economically. If I simply take the cost, subtract all the government incentives, and compute the lower power bills it looks like it would pay for itself in about eight years. But it isn't that simple. The money to buy the system has to come from somewhere.
I could lease the system but that does not appeal to me. I could borrow the money but then I'd have a loan to pay with interest; and we don't have any loans in our family. I could use cash but that means that amount isn't sitting in the stock market where it can easily double in less than eight years. In the end it wasn't about money after all. I just wanted it.
We live in Redding CA which NOAA says is the 2nd sunniest city in the U.S. after Yuma AZ. We get intense sun for six months, and lots of sun the other six months. Perfect for solar. Our house was consuming about 880 kWh per month in 2017. Due to city restrictions and practical roof space we ended up with a max 7.3kW system which, in the best conditions, can power the house 100%+ for about three summer months. But the other nine months we have to buy some power from the grid.
Where do we stand after almost a year? In 2017 we consumed 10,573 kW without solar. So far in 2018 we consumed 3,155 kW a saving of 7,418 kW. At our rates that is $1,112.7 annual savings. Apples to apples? Not at all. The solar system produced much more than that 7,148 kW because it also charged the Clarity all year. We've never charged away from home.
In 2017 we were driving a 2015 Toyota Prius so our auto fuel consumption was already low. We have a 4Runner but only drive it when we have to (only 71,128 miles on a 13 year old SUV). The above figures of electricity consumption are not just the house for 2018, but also include 100% of the charging for the Clarity. As for auto fuel savings at the pump we saved $1,017 this year. So the solar is working it's butt off for us. Total electricity and auto fuel savings $2,129.69 for 2018. Things should be slightly better in 2019.
The solar installer underestimated the capacity of the panels we selected and installed an under-powered inverter which was clipping at 5kW. That was corrected but we lost some potential power generation for three months.
We also had heavy smoke from the huge Carr fire for six weeks. Not only did the smoke partially block the sun, it also coated the solar panels. I had to wash them three times.
I was disappointed to notice late afternoon shade on the solar panels this week. We have two 50 foot and growing redwood trees that catch the low angle sun. The cost of topping those trees would never be returned in solar savings. Most of the year the sun is high enough so those trees aren't a problem.
The dramatic swings in power generation from the roof solar surprise me. Peak power is about 52kW per day midsummer when the days are long and the sun is high in the sky. A full sun day in December might produce 20kW. We've had days of near zero production when there is full overcast and rain. Surprisingly the system always manages some watts even on the worst days.
This chart shows grid power readings from our electric meter (net metering). Up slope means the solar system needed more help from the grid. Down slope means we were feeding power to the grid. We balance with the electric company once a year.
