I have too many demands on my time to be able to review this proposal unless you are willing to hire me for which I charge $250 an hour.
In general though, look for:
- Panels made by companies you recognize (like Panasonic, LG, Sunpower, and I just bought Solaria) so they have the staying power to honor the 25 year warranty. Don’t go with cheap panels from no-name companies many of which are Chinese.
- A 25-year panel power production warranty that allows you to make a claim based on the data in the app – avoid the warranties that require you to get the panel inspected.
- A 10-year “total energy per year from the entire array” warranty from the installer
- A 10-year roof penetration warranty if there are roof penetrations. If you have a flat roof get a quote for a ballasted system. If you have a standing-seam metal roof, great, the panels clamp onto the seams, if you have slate or shingles forget a roof mount and look at either ground mount or suppliers like NexAmp or community source aggregation in your town.
- Get the NPV, IRR and payback periods for the investment. Be wary of inflation calculations higher than 3% as they inflate the returns. Electricity prices (which determine your avoided cost or cost savings) are currently astronomical (almost 50c/kWh) because of the war in Ukraine and are likely to come down. I am currently using 25c/kWh plus 3% annual inflation in my projections.
- Barring these numbers (which are not easy to do properly) look for the cost per kWh over the guaranteed life of the panels. Calculate this by taking the net cost of the array (after tax breaks and subsidies) and dividing it by the guaranteed kWh produced per year, multiplied by 25 years. This should come out somewhere between 8-12c per kWh. The lower the better. Even the high end is a 50% discount to my 25c/kWh long term estimate for electricity prices and is by far the cheapest way to get electricity.
- If the cost differences and warranty differences are small, trust your gut and go with the installer you feel most comfortable with.
I hope this helps!
David Green – the “Green Guru”
The highly-acclaimed book “Zero Carbon Home”
How we cut our home’s carbon emissions to zero
The Easiest Way to Calculate Your Home’s Carbon Footprint:https://greenzerocarbonhome.com/2018/07/what-is-the-carbon-footprint-of-natural-gas-heating-oil-propane-and-coal/
Written Answers to over 300 Questions about Zero Carbon Homes:https://greenzerocarbonhome.com/webinar-questions-and-answers/
Finance and Net Zero Energy Terms explained: https://greenzerocarbonhome.com/energy-and-finance-terms-explained/
Zero Carbon Home Website Home Page: https://greenzerocarbonhome.com
Database of State Incentive for Renewable Energy (DSIRE) https://www.dsireusa.org
Published articles on Zero Carbon and Net Zero Energy:
Department of Energy, EnergySage, “Zero Carbon Home”https://www.energysage.com/project/7230/zero-carbon-home/
Zero Energy Project, “My Zero Energy Retrofit beats my 401k”https://zeroenergyproject.org/2018/09/23/my-zero-energy-retrofit-beats-my-401k/
Cool Effect, “Mr. Green’s Zero Carbon Home” https://www.cooleffect.org/content/news/green-testimonial?utm_source=Cool_Effect_CRM&utm_medium=EMAIL&utm_campaign=20180814Engage_Testimonial&utm_content=green_CTA
Green Energy Times, “My Zero Energy Pool is a Great Investment!” http://www.greenenergytimes.org/wp-content/uploads/2019/05/GET_May-2019.pdf
Published Presentations on Zero Carbon Zero Bills:
To see a 3-minute interview of David Green by NBC Boston anchor Joy Lim Nakrin, please click here:TV interview
To see a 20-minute TED talk at Harvard Business School, please click here: TED Talk
You can watch a recorded version of my Zero Carbon, Zero Bills webinar here: Zero Carbon, Zero Bills Webinar
Reviews of my “Zero Carbon, Zero Bills” webinar included, “Minute-for-minute, point-for-point, one of the best webinars I have ever attended. Thank you!”, “David is a true inspiration and asset to our community. He inspired us to get solar panels and a new front door”, “This is like a masterclass in ZeroCarbon”, “Thank you soooo much for the sensible advice and your fabulous resources!!” and, although this next comment is a little flowery, it does express the sentiment of many other comments, “Your contribution to Greening America is great and will probably help our survival as a species a bit longer than expected”.