RexRoller
1 mW
I work with a company that has installed about 1000 grid tied solar systems in the Bay Area. I have found most of our competition gives inaccurate solar quotes to people. People will show me a proposal from another company that shows the same system producing more kWh per year. I had our company pay for the bees knees in solar software (which is super expensive) but showed me how to accurately put together a solar production proposal.
Make sure to ask your contractor these questions.
1. Which roof spaces did you use to calculate my production?
2. Are you taking in consideration the azimuth of each roof space for production?
3. Did you use the correct azimuth?
4. How many watts will be used on each roof space?
5. Does your proposal include production data from PVwatts and my local weather station?
6. Did you include the 14% ish system losses?
Note: Most companies use a spreadsheet to guesstimate your kWh production. Many times the production will be based on a 180 degree, due south azimuth. This will significantly inflate the estimated kWh production. If the company is good, their software will account for the exact azimuth of each surface used and how many watts of solar modules will be on each surface.
7. If you want the most accurate forecast modeling available, make sure the company is using your "interval data" and not just an average monthly usage. For PGE this is the "green button" data when you login online.
8. Do you sub contract my install? We used to sub for other companies. We have to cut corners to keep up and do things we would never do when stamping our own company name on the install.
9. What is the warranty on the inverter? You want them to include the upgraded 20-25 year warranty on your inverters. The standard warranty is 10-12 years on string and hybrid inverters such as SMA and SolarEdge. They have an estimated lifespan of 15 years. Enphase micro inverters are more expensive but have standard 25 yr warranties. They will probably only talk about the 25 year warranty on the panels which is standard. The cost to upgrade a warranty is usually about $500. If you work it right, you should be able to get one of the companies to include it to win your business.
10. What financing is available? Get a loan calculator and check out the numbers on different interest rates and terms they offer. If you are going to pay it off early then probably a long term 20 yr 6-7% interest deal will give you the lowest monthly payments. There are deals out there such as 2.99% for 12 years (bank charges us 15% dealer fee!!). So we have to charge 15% more for the system total but if you are not paying it off early, you will save a ton of money in interest over a 20 year 6-7% loan on a system that costs 15% less. Solar is a numbers game and like ebikes, you can usually find a way to win.
11. What is my cost per watt installed? This may be the most important question for many folks. If you like them and they have good reviews and a competitive price per watt, I'd say you are good to go.
12. What kind of system monitoring comes with my system? You want this. Ask for it.
13. ?
I'll try to update this as I think of more info for you guys. I don't have experience with hooking solar to ebikes so I'm learning that with you guys here. I do have a pretty good grasp on grid tied systems for residential and commercial here in NorCal.
Thank you to all forum members. I built an ebike in April and have been over 1000 miles on it. I found trails I never knew existed. It had been a hell of a ride!!!
Make sure to ask your contractor these questions.
1. Which roof spaces did you use to calculate my production?
2. Are you taking in consideration the azimuth of each roof space for production?
3. Did you use the correct azimuth?
4. How many watts will be used on each roof space?
5. Does your proposal include production data from PVwatts and my local weather station?
6. Did you include the 14% ish system losses?
Note: Most companies use a spreadsheet to guesstimate your kWh production. Many times the production will be based on a 180 degree, due south azimuth. This will significantly inflate the estimated kWh production. If the company is good, their software will account for the exact azimuth of each surface used and how many watts of solar modules will be on each surface.
7. If you want the most accurate forecast modeling available, make sure the company is using your "interval data" and not just an average monthly usage. For PGE this is the "green button" data when you login online.
8. Do you sub contract my install? We used to sub for other companies. We have to cut corners to keep up and do things we would never do when stamping our own company name on the install.
9. What is the warranty on the inverter? You want them to include the upgraded 20-25 year warranty on your inverters. The standard warranty is 10-12 years on string and hybrid inverters such as SMA and SolarEdge. They have an estimated lifespan of 15 years. Enphase micro inverters are more expensive but have standard 25 yr warranties. They will probably only talk about the 25 year warranty on the panels which is standard. The cost to upgrade a warranty is usually about $500. If you work it right, you should be able to get one of the companies to include it to win your business.
10. What financing is available? Get a loan calculator and check out the numbers on different interest rates and terms they offer. If you are going to pay it off early then probably a long term 20 yr 6-7% interest deal will give you the lowest monthly payments. There are deals out there such as 2.99% for 12 years (bank charges us 15% dealer fee!!). So we have to charge 15% more for the system total but if you are not paying it off early, you will save a ton of money in interest over a 20 year 6-7% loan on a system that costs 15% less. Solar is a numbers game and like ebikes, you can usually find a way to win.
11. What is my cost per watt installed? This may be the most important question for many folks. If you like them and they have good reviews and a competitive price per watt, I'd say you are good to go.
12. What kind of system monitoring comes with my system? You want this. Ask for it.
13. ?
I'll try to update this as I think of more info for you guys. I don't have experience with hooking solar to ebikes so I'm learning that with you guys here. I do have a pretty good grasp on grid tied systems for residential and commercial here in NorCal.
Thank you to all forum members. I built an ebike in April and have been over 1000 miles on it. I found trails I never knew existed. It had been a hell of a ride!!!
