Time for my fourth annual solar power progress report. This is the fourth year of having solar panels on my roof (for the full story click here), and production has been humming along. For 2018, the panels produced 3591 kilowatts of power, 6 kilowatts less than last year. Below is a chart of my 4 years of production by Month:
We had a sunnier than average year overall, however our summer skies were filled with smoke from wildfires, and I think that is what kept me from beating last years number.
As I have mentioned in previous posts, I had originally penciled out a 6 year payback when I made the decision to move forward with this plan. Last year I was projecting an 8 year payback on my investment, and this year, that is looking optimistic for the following reasons:
- Drop in Incentives. While may incentive rate per kilowatt remained at 50 cents for 2018, I think it is highly unlikely the rate will be above 20 cents after 2020. It may even be 0, as the only reason I am getting an incentive is because my installation was grandfathered in (if I am reading the revised code of Washington correctly). New solar installations do not receive any incentives, which has pretty much stopped installations as the payback is just not there.
- Electricity rates dropping. My assumption back in 2015 assumed electricity rates would increase around 5% a year, given the cost of phasing out coal generated electricity. In 2015, Puget Sound energy was charging 11 cents a kilowatt. My latest electricity bill shows the current price at 9 cents a kilowatt, down 18%. There doesn’t seem to be any pressure to reduce energy production from coal, as Puget Sound energy uses coal from a plant in Montana to generate 38% of its electricity:
Given this drop in incentives and electricity prices, I am now targeting a payback of 15 – 18 years. When the incentives presumably end in 2020, my annual revenue will be in the neighborhood of $370 dollars, unless electricity spikes back up or if they extend the incentive program past 2020.
The good news is the panel production has not been significantly dropping off, so they should last for a long time. Interestingly, I noticed on Amazon.com that you can buy panels now for about 80 cents a watt, the first time I have seen it under a dollar. I suppose if I wanted to double down on solar power, I could buy them as they get cheaper to reduce my payback time. I think some rough calculations show that at 80 cents a watt, that would have around a 4 year payback, assuming I could easily add them into the current array.
Regarding maintenance, still pretty easy. Twice a year or so I use a mop to wash them off with dish washing soap, then rinse them. I don’t notice a big spike in production after I clean the panels, so more frequent cleaning doesn’t seem to make sense. I am collecting a lot of tree debris underneath the panels, so I may have to figure out how to clear that out so as to not hurt my roof from rot. I may invest in some racks that elevate the panels so I can clean under them, and the racks also allow for better angles for the sun.
Power Use Report
As long as we are on the subject of power, I also recorded my power usage again this year. Usage was down again this year, but by only 1%. I again attribute it to replacing more lights with LEDs as the old incandescent ones burn out. I am guessing one of my biggest power expenses if the refridgerator, and we got a new larger one this year, so I will not be surprised if my power usage is up next year.
Overall, still happy with my investment, and I still think residential solar / utility scale wind and solar is the power model of the future. I will get most my investment back in the first 5 years, so it still wasn’t a bad investment in a low interest rate world.