Net metering rules are very different in my state.

Q: In Colorado, our grid-tied solar is restricted to 120% of historical kWh usage. Your solar panel system is massive. Is your system restricted in size OR are you actually using that much electricity? Where is most of your electrical usage in your home?

A: Net metering rules (and the subsidy rules, which are different entirely) vary a lot by state and even by town within a state and even then by utility company within a town. In MA, net metering is generous but there are many limits to net metering. Under 10kW you get 100% credit for any power you export. Above 10kW and below 25kW you get only 60% credit for the excess power not 100%. Above 10kW the utility has to approve your system and if there is, say an overloaded transformer on your street, they will not approve it. The SMART subsidy (the MA subsidy for solar power) drops to almost zero above 25kW, but then it goes up if you add a battery or install the array as a canopy over a parking lot. If you install it over a farm field and maintain the agricultural use, it goes up again. So you just have to pick through your local rules and try to optimize financially. In my experience in MA today, the financially optimal array is just under 25kW with battery back up.


My arrays generate slightly more electricity than I use throughout the year. Most of that electricity now goes on our heat pumps because we use almost no heating oil.

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