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Massachusetts Solar Calculator

Enter your utility and monthly bill — get system size, SMART 3.0 incentive, net metering savings, property tax exemption, and 25-year savings.

Your Massachusetts solar inputs
$
kW
Massachusetts solar estimate
20 × 400W panels (8 kW system)
Recommended size for your bill: 5.7 kW
Monthly usage571 kWh/mo
Annual production (MA 4.2 PSH)9,811 kWh/yr
Annual savings (net metering)$2,747/yr
Gross system cost$24,800
Federal ITC (30%)-$7,440
Sales tax exemption (6.25%)-$1,550
Net cost after ITC$17,360
SMART 3.0 income (15yr total)$13,245
Property tax exemption (20yr est.)$7,440
Payback period6.3 yrs
25-year savings$68,678
SMART 3.0 pays $0.06–$0.12/kWh for all production for 15 years. Estimated at $0.09/kWh avg. Actual rate depends on adder categories (low income, ground mount, etc.). Enroll through your utility before installation.
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How to Use This Calculator

Enter your bill and select your utility

Massachusetts has some of the highest electricity rates in the continental US at $0.25–$0.28/kWh, making solar economics particularly attractive. Enter your average monthly electric bill and select National Grid, Eversource, or Unitil — the three regulated utilities in Massachusetts. The calculator uses your bill to estimate your consumption and how much solar could offset it.

Enable SMART 3.0 enrollment

The SMART (Solar Massachusetts Renewable Target) program is one of the most valuable state solar incentives in the US. SMART 3.0, launched in 2024, pays you an additional $0.06–$0.12/kWh for every kWh your system produces for 15 years — on top of what you save through net metering. The rate depends on adder categories including low-income housing, ground mounts, and community solar. Enroll through your utility before your system is interconnected.

Massachusetts net metering and property tax exemption

Massachusetts has full retail-rate net metering — every kWh you export to the grid earns you a credit at your full retail electricity rate. Solar systems are also fully exempt from property tax increases for 20 years, and all solar equipment is exempt from the 6.25% Massachusetts sales tax.

The Formula

Monthly kWh = Monthly Bill ÷ Electricity Rate Annual Production = System kW × 1000 × 4.2 PSH × 365 × 0.80 efficiency ÷ 1000 Annual Savings = Annual Production × Retail Rate (full net metering) Gross Cost = System kW × 1000 × $3.10/W + Battery ($12,000 if added) ITC Credit = Gross Cost × 30% Sales Tax Savings = Gross Cost × 6.25% SMART Income = Annual Production × $0.09/kWh × 15 years Property Tax Exemption = Gross Cost × 1.5% × 20 years (est.) Payback = Net Cost After ITC ÷ Annual Savings

Massachusetts uses 4.2 peak sun hours (PSH) statewide average — Boston gets about 4.1 PSH, Worcester 4.0, Cape Cod 4.4. The $3.10/W installed cost reflects MA's slightly higher labor costs versus national averages. SMART income is estimated at $0.09/kWh — the midpoint of the $0.06–$0.12/kWh range depending on adder categories. Property tax exemption calculated at 1.5%/yr — actual MA property tax varies significantly by town.

Example

Sarah — Suburban National Grid customer with SMART enrollment

Sarah is in suburban Massachusetts (National Grid) paying $160/month at $0.28/kWh. She installs an 8 kW system and enrolls in SMART 3.0.

Monthly bill$160 (National Grid, $0.28/kWh)
System8 kW, SMART enrolled, no battery
LocationSuburban MA (4.2 PSH)

Result

Annual production~9,676 kWh/yr
Annual savings (net metering)~$2,709/yr
Gross system cost~$24,800
Federal ITC (30%)-$7,440
Sales tax exemption-$1,550
Net cost after ITC~$17,360
SMART 3.0 income (15yr)~$13,068
Payback period~6.4 years
25-year savings~$67,725

Sarah's combination of Massachusetts's high electricity rates, full net metering, SMART 3.0 payments, and the 30% ITC creates one of the most compelling solar ROI cases in the US — a payback under 7 years and over $67,000 in lifetime savings from a $17,000 net investment.

FAQ

SMART (Solar Massachusetts Renewable Target) is a production-based incentive that pays you for every kWh your solar system generates, in addition to net metering credits. SMART 3.0 launched in 2024 with rates ranging from $0.06 to $0.12/kWh for 15 years depending on adder categories. Higher adders apply for low-income properties, ground-mounted systems, community solar, and building-integrated systems. The base rate is set by capacity block — earlier blocks had higher rates. Enrollment must happen before your system is interconnected. Contact your utility (National Grid, Eversource, or Unitil) to check current block availability and enrollment steps.
Massachusetts has full retail-rate net metering: every kWh you export to the grid earns a credit equal to your full retail electricity rate (currently $0.25–$0.28/kWh). Credits roll over monthly and can be used in future billing periods. This is more generous than many states that credit at the lower "avoided cost" rate. Residential systems up to 25 kW qualify automatically. For systems over 10 kW there may be a small interconnection fee. Net metering rules are set by the MA DPU and have remained stable — no changes are currently proposed.
Yes — all solar panels, inverters, batteries, and installation materials are exempt from Massachusetts's 6.25% sales tax. This exemption applies automatically — you do not need to apply for it. On a typical 8 kW system at $24,800, this saves about $1,550 immediately. The exemption includes battery storage systems purchased alongside solar. This is a straightforward savings that applies to every Massachusetts solar installation.
Yes — Massachusetts law (MGL Chapter 59, Section 5, Clause 45) exempts solar energy systems from property tax assessment for 20 years from installation. This means your home's assessed value for property tax purposes does not increase due to a solar installation during that period. Massachusetts property taxes vary significantly by municipality ($8–$22/per $1,000 of assessed value), but a typical suburban town at 1.5% means a $25,000 solar system that would otherwise add $375/year to your tax bill is instead exempt — saving approximately $7,500 over 20 years.
Massachusetts previously offered a state solar tax credit (15% up to $1,000), but it expired in 2023. The primary state incentive is now SMART 3.0, which is more valuable than the old tax credit for most homeowners. The federal 30% ITC still applies to all Massachusetts residents. Combined with SMART payments, sales tax exemption, property tax exemption, and full net metering, Massachusetts remains one of the top 5 states for solar ROI despite losing the state tax credit.

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