Solar PV Up (and not yet running)

Three days and a swarm of people and the solar array is UP.

But not up and running, yet. We still need the town to inspect the electricity and the building, NSTAR to approve the interconnection, to install the monitoring system, someone to commission the system, and us to be trained in its operation and maintenance. Another week or so…

But in the meantime, here is the info for our system:


24 SANYO HIT Power Modules 100% of maximum power (Pmax) = 215.0 Watts / DC rate per panel 210 Watts / Total = 5040 Watts system

12 Enphase D380 module-direct inverters

Modules are placed in portrait orientation and racked as two rows of twelve modules each. Each row of modules is as a single string with six inverters, resulting in a total of two strings.

Production estimates

Estimated first year production in kWh: 4,735

This estimation takes into account historical weather data, the orientation of the south-facing roof and the tilt of the south-facing roof.

At this production rate, our solar fraction would be around 87% of our 2010 electrical consumption which translates to avoided utility costs of approximately $899 per year (this value is based on your current utility rate of $0.18 per kWh).

Value of solar energy harvested over project life: $ 50,922.89

Carbon Savings

Pounds of carbon saved in the first year: 7,103

Pounds saved over the project lifetime: 187,469

Cost (estimates, but close)

Base system cost: $ 35,558.00
Projected Commonwealth Solar rebate: $ 8,000.00
Invoice cost: $ 27,558.00
Federal Tax Credit (30% of remaining cost): $8,260
State Personal Tax Credit: 15% of remaining, up to $1000
Cost after installation: $18,290
minus yearly deductions beginning in year 1:
  • savings on our electricity bill per year: $900/year at our current utility rate of $0.18 per kWh > assuming prices don’t change, the system pays for itself in approx. 20 years
  • and we can sell 5 SRECS a year. At the moment SRECS are worth $520 each, but assuming the worst-case scenario with the lowest value per SREC at $285 each (so $1425/year), then the system is paid for in approx. 8 years.

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