The SMART payment is a difference, not an addition
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 a projection that adds a full net metering credit and a full SMART payment together overstates what arrives. Ask your installer to show both across a year and explain how the monthly difference is calculated. That request alone will tell you whether the model was built from the programme mechanics or from a template.
Ask what the projection assumes after year ten. For residential systems under 25 kW SMART payments last a fixed term of 10 years, while the system lasts considerably longer, so a long projection has to show the drop.
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 with a defined end date.
The production estimate does double duty
Because the incentive is paid on metered production and net metering credits exported energy, the production estimate feeds both streams. An optimistic figure inflates the projected result twice rather than once, which makes it the assumption most worth testing.
Ask whether it was modelled for your specific roof, orientation and shading rather than derived from a regional average, and ask to see monthly figures rather than an annual total.
Ask for a shading assessment covering the whole year rather than the hour of the site visit. Mature tree cover is one of the better things about living here and one of the harder things about rooftop solar.
Ask what happens if actual production falls materially short, and get the estimate and that answer into the contract. An estimate that appears only in a sales presentation is not a commitment.
What belongs in the contract
Get equipment specified by manufacturer and model number rather than by description. Model numbers are what make a warranty enforceable later and what let you compare two quotes on the same basis rather than on adjectives.
Establish who honours each warranty and for how long. Panels, inverter and workmanship are commonly covered by three different parties on three different terms, and a company that has left the market cannot support a workmanship warranty however well drafted.
Ask what the workmanship warranty covers on roof penetrations specifically. Leaks around mounting hardware are the most common physical failure in residential solar and they typically appear a few years in.
Confirm a production meter is included and reporting, and agree in writing who files the permit, who submits the SMART application and who schedules inspections. On a project with three separate processes the common failure is each party assuming another handled one.
Three state benefits, and the federal one that ended
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, claimed on Schedule EC. It being available to a tenant as well as an owner is unusual and worth knowing.
Massachusetts also provides a property tax exemption of 100 percent for 20 years for solar installations, so the improvement does not raise your property tax bill the way a renovation of similar cost would.
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. Check that your quote reflects that rather than assuming, and ask your municipal assessor what if anything they need for the property tax exemption at your address.
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.