How the two mechanisms actually combine
Massachusetts offers net metering for residential systems, crediting exported solar at or near the retail or basic service rate, and layers the SMART production incentive on top.
SMART payments are made directly by the utility to the system owner via the same billing structure as net metering. Each month the utility reads the production meter, and the owner receives a payment representing the difference between the SMART rate and the value of the energy already credited through net metering.
So the SMART payment is a top-up to a defined level rather than a separate payment stacked on at full value. A projection that adds a full net metering credit and a full SMART payment together is overstating what arrives.
Ask your installer to show both across a year and to explain how the monthly difference is calculated. That single request will tell you quickly whether the projection was built from the programme mechanics or from a template.
Ten years of payments, then net metering alone
For residential systems under 25 kW, SMART incentive payments last for a fixed term of 10 years, at a rate determined when you enrol and locked for the duration.
A solar system lasts considerably longer than ten years, so a long savings projection has to show what happens in year eleven when the incentive stops and net metering carries the return on its own.
Ask to see the figures with SMART removed entirely. That is your floor, and it tells you how much of the case depends on income that has a defined end date.
Ask what the current residential rate is and what determines which rate your system receives. Under SMART 3.0, launched in October 2025, residential systems under 25 kW are no longer subject to capacity block limits, but the rate is still set at enrolment.
Two things to confirm before you sign
Confirm you are eligible. SMART is provided to customers of Eversource, National Grid and Unitil, and customers of municipal light plants are not eligible. Massachusetts has approximately 40 municipal light plants, so this is a real question rather than a formality.
Confirm the production meter. Because the incentive is paid on metered production, a production meter has to be installed and reporting for you to be paid at all. Ask in writing who supplies and installs it and how its readings reach the programme.
Then ask how you can verify it is still reporting a year later. Missing incentive payments are far easier to overlook than a missing bill credit, and a fault costs you part of a ten-year entitlement.
Keep the interconnection approval, the SMART application approval and the meter details together. That file is what you need if something has to be corrected and what a buyer of the house will want to see.
Three state benefits, and the federal one that ended
Massachusetts has a state income tax credit of its own. Under 830 CMR 62.6.1 an owner or tenant of a residential property who occupies it as their principal residence is allowed a solar and wind energy credit against personal income tax equal to fifteen percent of the net expenditure for renewable energy source property, or $1,000, whichever is less. It is claimed on Schedule EC.
Note that it is available to a tenant as well as an owner, which is unusual and worth knowing if you are paying for a system on a property you occupy but do not own. Ask a tax advisor how it applies to your circumstances, since a credit is only worth what you can use against tax owed.
There is also a property tax exemption of 100 percent for 20 years for solar installations, and equipment for a solar system used as a primary or auxiliary energy source in a principal residence is exempt from sales and use tax. Neither arrives as a cheque, which is exactly why both get left out of people's own arithmetic.
On the federal side, the 30 percent Residential Clean Energy Credit under Section 25D expired for property placed in service after December 31, 2025, so a cash or loan purchase now receives no federal credit. Section 48E survives at 30 percent for third-party owners under leases and power purchase agreements, so ask any such provider what they claim and what of that value reaches you, and confirm with a tax advisor.