Hi - I'm working with a Tesla Energy advisor for a 27kw residential roof (tiles, not panels) system on Cape Cod / Eversource Eastern MA R1. I spent hours researching the SMART incentive program enough to understand how to build a spreadsheet to capture the IRR, but I failed to recognize my install would be in the >25kw category which seems more complicated. If I use the
SMART-BTM-Value-of-Energy-Workbook calculator (ex storage), I get a measly SMART incentive payment of $0.0196/kWh, whereas it would be $0.0918/kWh under the <25kw category (and a compelling ROI). Granted, the lower incentive rate is for 20 years rather than 10, but it absolutely kills the project economics unless I'm failing to account for additional economic gains from moving to the >25kw category. I'm reasonably certain I understand the storage adder, although given Eversource doesn't have time-of-use rates, the economics on the Powerwalls appear awful to me as well.
So, 2 questions if anyone can help:
1) Does moving to the >25kw category provide any additional economic incentives (other than volumes) that the SMART incentive calculator fails to capture? Or am I stuck with a lower return despite offsetting more of my usage (seems perverse to dis-incent lower CO2 consumption)?
2) Is there a compelling economic case for the Powerwalls other than peace-of-mind? I already have a propane-fired generator, so continuity in an outage is not an issue and therefore has no value to me other than the lower propane consumption. But, if I'm doing the math right, the #s stink. Net cost of 2 powerwalls $12,580 ($17k for bundling discount less 26% fed taxes) goes into denominator. $0.0357 incentive adder * 20,400kwh annual estimated production = ~$730 * 10 years * (1-.46 marginal tax rate) = $3,940 as one component of the payback. Second component is Connected Solutions (2 powerwalls, assume 4kw average discharge from each * $225/kw = $1800 pre-tax or $972 post-tax * 5 years = $4,860. Add the two payback components ($3,940 + $4,860) = ~$8,800 vs a $12,580 after-tax install cost. My propane consumption for backup generation is modest, so this really doesn't seem to pencil unless I'm missing something. Any other thoughts/perspectives/missing points would be welcome.
Thank you in advance! I'm a finance/#s guy, and can't believe the info to piece this together is so difficult to find in so many disparate places.