raydias wrote: »
- Would it be possible to see the paperwork submitted to the local inspector? (with any personal info redacted)
- Does the leasing company have someone come out and inspect the system as well as clean the panels? If not it would be interesting to see what cleaning the panels does for production now that we are heading into summer.
- If you reduced your consumption would your cash flow increase?
thanks for sharing the experience
Feel free to ask questions here. Others may benefit.
The system is in it's 6th year. It's performance is carefully measured, and can be publicly viewed here:
These charts range from real time to historical rolling last 13 month charts.
Key learnings have been:
1. The best sustained energy performance my system (36 Astronergy 225W panels mounted with 2 roof orientations and connected as 3 strings into a 7000W Sunny Boy inverter) is currently capable of is about 35 kWh per day. It is right now, early Aug., that I get this sustained performance, annually. While it's hot here (over 100 degree days continuously) at the moment, the days are still long and the weather has few clouds.
2. The period of best one day energy performances my system is currently capable of long ended 3 months ago. In the early May time frame days are still long, and temperatures are cooler. Best one day performance this year is about 42 kWh.
3. What you see is with no maintenance since 2010 installation. Since I don't own the panels I'm reluctant to sweep ice off of them in the winter (scratching) or spray them with potable, chlorinated drinking water (spots).
4. One of the charts has the monthly PV Watts numbers for my exact location. It's in the month of August that I actually come close to producing what PV Watts predicts. For the rest of the months I always produce less than PVWatts estimated performance. December is the worst month, where I only produce about half of what PVWatts says I should be. All of this less than PVWatts predicted performance is due to design deficiencies of my system long discussed in this thread.
5. On another chart, my utility, in 2009, paid a lot of incentive money to my installer. In return, they're requirement was that the array had to produce at least 62% of PVWatt's estimate. On an annual basis, it does (it's about 68% - blue line). On a monthly basis, it does not general for the months of Nov., Dec., Jan. and Feb.
6. My leasing arrangement was no up front money required of me. All components were installed, and are owned by the solar installer. Every year now I am approximately $250 cash flow positive per year, from day one. This is net of the three cash flows that influence the subject: The savings of kWh I'd otherwise have to pay, the payments from the utility for kWh I put on to the grid, and the monthly lease payment to the installer. Through 2015 I have saved $1500 for an investment of $0. Not big numbers but always cash flow positive, and, I'm doing good for the environment.
Hope this helps.
Sometimes I get asked about long term performance and degradation.
The online measurement system referenced earlier is configured to be real time to about 13 months. To analysis numbers all the way back to installation I have to do it with a 'batch' process.
Here's the chart for annual performance. It shows 'Year Beginning' numbers - i.e. 2011, 12, 13, 14 and 15 - six years of annual numbers (ignore the months on the x axis).
While the chart suggests that annual deterioration is significant, I don't have annual kWh output rationalized to weather conditions, and thus I believe it's too soon to make any conclusion on long term performance.