Establish who controls the roof
If you own a unit in a multi-family building, find out what the governing documents say about common elements and who has authority over the roof. That determines whether a personal installation is possible at all, or whether the sensible route is a building-level project.
If you rent, the roof is not yours to alter and a landlord has to be part of the conversation from the beginning rather than being asked at the end.
If the building is one you own and rent out, ask how net metering credit works when a tenant holds the electricity account, since that determines who receives the bill savings and who receives the incentive. Settle it before installation.
Ask your utility what options exist for customers who cannot install on their own roof. It is a short call and worth having before concluding solar is unavailable to you.
Small roofs, shading, and honest estimates
Ask how the usable roof area was calculated and what setbacks or access requirements reduce it. On a small or complicated roof the answer is frequently well below what the roof looks like it should hold.
Ask for a shading assessment covering the whole year rather than the hour of the site visit. In dense housing, neighbouring buildings and mature trees create shading that shifts substantially between seasons, and it is the largest single threat to a production estimate.
Ask whether the production estimate 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.
Orientation is the decision that most affects output and cannot be recovered later with better equipment. On a constrained roof, being honest about that early is better than discovering it after installation.
Why a modest system still works here
Massachusetts offers net metering crediting exported solar at or near the retail or basic service rate, and the SMART incentive is paid on metered production. Neither mechanism penalises a smaller system in the way an export-rate regime elsewhere would.
For residential systems under 25 kW, SMART payments last a fixed term of 10 years at a rate determined when you enrol. Under SMART 3.0, launched in October 2025, residential systems under 25 kW are no longer subject to capacity block limits.
Confirm your eligibility first, since SMART is provided to customers of Eversource, National Grid and Unitil and customers of municipal light plants are not eligible.
Then confirm a production meter is included and reporting, because the incentive is paid on metered production. On a small system every part of the entitlement matters proportionally more, not less.
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.