Massachusetts solar calculator
Estimate system size, panels, roof space, gross cost, savings, and payback using Massachusetts starter assumptions.
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Enter monthly kWh or electric bill. The calculator uses state-level assumptions and shows the math behind the result.
Your estimate
Example resultEstimated system size: 8.3 kW. This is an estimate, not an installer quote.
Confidence
Medium
Planning estimate only — not an installer quote, engineering design, or tax advice.
Payback uses gross system cost before verified incentives, financing fees, batteries, and roof work.
Annual usage: 10,800 kWh
Annual production target: 10,800 kWh
State rate: 29.61 cents/kWh
Export assumption: Partial export credit
Direct solar use: 5,940 kWh
Modeled exports: 4,860 kWh
Panel count view
19-23 panels
Estimate shape
Privacy note: the printable report link stores estimate inputs in the URL, including ZIP and usage or bill values. Keep it private if those details are sensitive.
Local scenarios
Compare a few assumptions without creating an account.
Saved scenarios stay in this browser only and may include ZIP, bill, and usage inputs. SolarCalcNow does not sync them or send those values to analytics.
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Confidence drivers
Expected production: 10,800 kWh
System loss: 14%
Export value: Partial export credit
Direct solar use: 5,940 kWh
Modeled exports: 4,860 kWh
State production default: 1,304 kWh/kW/year
EIA Electric Power Monthly, Table 5.6.A — June 2026 - 2026-09-04
NLR PVWatts V8 · author-selected reference point - 2026-09-04
EnergySage marketplace + SolarCalcNow cost scenario - 2026-09-04
Production evidence: California has a saved full PVWatts response; eight states have successful API yields recorded to two decimals. Colorado, Illinois and Pennsylvania retain explicit author assumptions. The download distinguishes these evidence levels.
$0.2961/kWh
29.61 ¢/kWh
EIA Table 5.6.A, June 2026 residential column; published August 26, 2026. Divide the published cents/kWh by 100. This preliminary statewide average is a fallback, not your utility tariff. Use your bill's energy-only rate; fixed charges remain payable.
1,304.2 kWh/kW/year
kWh/kW/year
PVWatts V8 typical-weather model at an author-selected reference point in the state: 4 kW DC, roof mount, 20° tilt, 180° azimuth, 14% system losses. Annual AC kWh ÷ 4 gives kWh/kW/year. Losses are already included and are not deducted again. Neither a statewide average nor a ZIP or roof survey. Shade and ±10% production bounds are separate author scenarios.
$2.33–$3.49/W
$2.91/W × 0.8…1.2
EnergySage's state marketplace average, table updated August 28, 2026. We calculate an author-selected range of average × 0.8 to average × 1.2, rounded to cents/W. This ±20% scenario is not an observed price distribution or confidence interval. Cash solar only, before incentives; compare like-for-like local quotes.
SolarCalcNow provides planning estimates only. Results are not installer quotes, engineering designs, tax advice, financing recommendations, or utility interconnection approval.
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Installer quote matching is not active yet. You can still calculate, save, and print your estimate before contacting installers directly.
State-specific review
These planning notes interpret the same source-linked inputs used by the calculator. They do not add an incentive, utility tariff, or site-specific claim to the estimate.
Massachusetts electricity rates can make self-consumed solar valuable, but a new 2026 purchase should still start with gross cost. SolarCalcNow's reviewed IRS record treats the homeowner Section 25D credit as unavailable for expenditures after the 2025 cutoff and therefore does not subtract it from the default estimate. Older examples that assume a federal percentage can produce a net price and payback that no longer describe a new project. Keep every state, utility, storage, income-qualified, or local claim outside the base calculation until its primary source, active status, eligibility, ownership, amount, and timing are verified for the household. This preserves a comparable pre-incentive baseline.
Sources: IRS Section 25D update (reviewed 2026-09-04); EnergySage marketplace + SolarCalcNow cost scenario (reviewed 2026-09-04)
The state production assumption and the residential rate do different jobs. Production determines the system capacity needed for annual energy; the rate values electricity avoided by direct solar use. A high rate can improve modeled savings, but it cannot compensate for an inaccurate roof assessment. Snow, shade, pitch, azimuth, separate roof planes, setbacks, and seasonal output can move the site result. Compare the calculator's state-level kW with the installer's monthly production model, and ask for its loss assumptions. If the proposal reaches a shorter payback mainly through a higher rate rather than better verified production or a lower gross price, that difference should be visible.
Sources: EIA Electric Power Monthly, Table 5.6.A — June 2026 (reviewed 2026-09-04); NLR PVWatts V8 · author-selected reference point (reviewed 2026-09-04)
The EIA rate on this page is a statewide residential average used for consistent early planning. It is not a reconstruction of the household's utility tariff and does not guarantee that solar can remove every charge. Fixed fees, minimum bills, supply and delivery structure, time periods, taxes, and export settlement can remain. Review twelve months of billed kWh and energy charges, then compare the calculator input with the actual plan. Ask any installer using rate escalation to provide a zero-escalation case as well. SolarCalcNow keeps the current rate flat so users can identify how much of a payback claim comes from today's inputs and how much comes from a forecast.
Sources: EIA Electric Power Monthly, Table 5.6.A — June 2026 (reviewed 2026-09-04)
The same Massachusetts panel count can produce different savings when household demand and solar output occur at different times. Electricity used immediately avoids a purchase at the modeled retail rate; exported energy follows the selected export-value scenario. SolarCalcNow keeps those streams separate and does not claim one utility-specific settlement rule from a state average. Run retail, partial, and low export cases while holding system size constant, then compare the spread with the applicable current tariff. Batteries may shift timing and add resilience, but they also add cost and losses, so evaluate a battery as its own scope rather than assuming it automatically improves solar payback.
Sources: EIA Electric Power Monthly, Table 5.6.A — June 2026 (reviewed 2026-09-04); NLR PVWatts V8 · author-selected reference point (reviewed 2026-09-04)
The source-linked cost-per-watt range is a market planning benchmark. It does not include enough property detail to approve or reject a quote. Calculate price per watt from the solar-only gross price and DC system size, then separate roofing, structural work, batteries, service upgrades, trenching, financing charges, and program-dependent adders. Ask for the exact panel and inverter models, AC and DC capacity, monitoring, warranty responsibility, production assumptions, and excluded work. A proposal outside the benchmark may have a legitimate scope reason, but that reason should be documented. Monthly payment alone cannot show whether two Massachusetts proposals contain the same equipment, work, or financing cost.
Sources: EnergySage marketplace + SolarCalcNow cost scenario (reviewed 2026-09-04)
Start with household bills, pass the annual kWh through the transparent state model, and require the installer to replace remaining uncertainty with site evidence. The bills establish demand. SolarCalcNow exposes the state rate, production, cost, losses, panel wattage, and export assumption. A site proposal should add measured roof geometry, shade, electrical condition, interconnection scope, equipment, schedule, and written price. Incentive claims belong in a separate source-checked layer and should not silently reduce gross cost. If the three records disagree, adjust one input at a time and preserve the comparison. That produces a traceable decision instead of selecting the largest savings claim or shortest unsupported payback.
Sources: EIA Electric Power Monthly, Table 5.6.A — June 2026 (reviewed 2026-09-04); NLR PVWatts V8 · author-selected reference point (reviewed 2026-09-04); EnergySage marketplace + SolarCalcNow cost scenario (reviewed 2026-09-04)
Production evidence: California has a saved full PVWatts response; eight states have successful API yields recorded to two decimals. Colorado, Illinois and Pennsylvania retain explicit author assumptions. The download distinguishes these evidence levels.
$0.2961/kWh
29.61 ¢/kWh
EIA Table 5.6.A, June 2026 residential column; published August 26, 2026. Divide the published cents/kWh by 100. This preliminary statewide average is a fallback, not your utility tariff. Use your bill's energy-only rate; fixed charges remain payable.
1,304.2 kWh/kW/year
kWh/kW/year
PVWatts V8 typical-weather model at an author-selected reference point in the state: 4 kW DC, roof mount, 20° tilt, 180° azimuth, 14% system losses. Annual AC kWh ÷ 4 gives kWh/kW/year. Losses are already included and are not deducted again. Neither a statewide average nor a ZIP or roof survey. Shade and ±10% production bounds are separate author scenarios.
$2.33–$3.49/W
$2.91/W × 0.8…1.2
EnergySage's state marketplace average, table updated August 28, 2026. We calculate an author-selected range of average × 0.8 to average × 1.2, rounded to cents/W. This ±20% scenario is not an observed price distribution or confidence interval. Cash solar only, before incentives; compare like-for-like local quotes.
Source coverage: Eversource · National Grid · Unitil
State-regulated net metering covers the listed investor-owned utilities. Municipal light plants have separate rules. Check facility class, cap exemption, tariff and credit allocation; SMART enrollment does not determine export credits.
Read the primary source — Massachusetts net-metering eligibilitySource checked: · Next review due: 2026-10-04
Source coverage: Massachusetts · SMART participating utilities
MassCEC lists $0.03/kWh for most systems up to 25 kW in 2026, or $0.06/kWh for qualifying low-income customers. Qualification locks the rate for 20 years. Confirm utility and application eligibility.
Read the primary source — SMART 3.0Source checked: · Next review due: 2026-10-04
Program documented; eligibility required · Not subtracted from calculator cost
Planning example
This example uses the same calculator engine as the interactive form: 400W panels, low shade, 100% target offset, and no ZIP-level PVWatts override.
System size
8.3 kW
Panel range
19-23 panels
Roof area
507 sq ft
Gross cost
$19,294-$28,900
Annual savings
$2,263
Simple payback
8.5 years-12.8 years
For a home using 900 kWh per month in Massachusetts, the default planning estimate is a 8.3 kW system with 19-23 panels at 400 W each, producing about 10,800 kWh per year and needing roughly 507 sq ft of roof. Estimated gross cost is $19,294-$28,900 before incentives, with simple payback of 8.5 years-12.8 years. The estimate uses EIA Electric Power Monthly, Table 5.6.A — June 2026 (updated 2026-09-04) and NLR PVWatts V8 · author-selected reference point (updated 2026-09-04).
Usage sensitivity
These rows keep every input fixed except monthly usage. If your home is closer to 600 or 1,200 kWh/month, this gives a faster sanity check than reading one generic state paragraph.
| Usage | System | Panels | Gross cost | Payback |
|---|---|---|---|---|
| 600 kWh/mo | 5.5 kW | 12-16 | $12,863-$19,266 | 8.5 years-12.8 years |
| 900 kWh/mo | 8.3 kW | 19-23 | $19,294-$28,900 | 8.5 years-12.8 years |
| 1,200 kWh/mo | 11.0 kW | 26-30 | $25,725-$38,533 | 8.5 years-12.8 years |
Local context
Very high electricity rates can support savings even with lower annual solar yield.
Before using this as a purchase decision, compare a no-battery and battery quote, verify your utility export rate, and check current incentives from state or utility sources.
For a home using 900 kWh per month, the Massachusetts starter model estimates about 8.3 kW, 19-23 panels, roughly 507 sq ft of roof area, and a gross installed-cost range of $19,294-$28,900. Simple payback is shown as 8.5 years-12.8 years before verified incentives, financing, batteries, roof work, or utility-specific export rules.
Massachusetts estimates use 29.61 cents/kWh as the residential rate assumption. Higher retail rates can improve the value of self-consumed solar, while lower rates usually make system size, export credit, and installed cost more important to the payback result.
Massachusetts savings are rate-sensitive; net metering, program rules, and utility territory can change the value of excess production. SolarCalcNow's default advanced setting models exported kWh below retail value until utility-specific rules are verified. This keeps the planning estimate conservative when a home exports more power than it uses immediately.
The current production assumption is 1,304 kWh per kW per year. This is a state-level starter value, not a roof-specific PVWatts result. Actual output can change with azimuth, tilt, shade, snow, weather, usable roof planes, setbacks, inverter choice, and module degradation.
The gross cost range uses a starter benchmark of $2.33-$3.49/W. SolarCalcNow does not subtract incentives from this estimate unless each incentive has an official or reviewable source, updated date, eligibility note, active status, and explicit permission to be included in net-cost math. Use the quote checker to compare installer price per watt against the same gross-cost baseline.
Data status
Electricity rate
EIA Electric Power Monthly, Table 5.6.A — June 2026
Updated 2026-09-04 - Confidence: official
Solar production
NLR PVWatts V8 · author-selected reference point
Updated 2026-09-04 - Confidence: official
Installed cost
EnergySage marketplace + SolarCalcNow cost scenario
Updated 2026-09-04 - Confidence: market-benchmark
FAQ
Start with a full-year average of monthly electricity use, then choose how much of that use the system should offset. The Massachusetts calculator converts annual kWh into a system-size estimate using the visible state production assumption, shade setting, and system-loss factor. It then divides system watts by the selected panel wattage and shows a range rather than pretending the roof layout is known. Higher-wattage modules can reduce the count for the same system size, while setbacks, vents, separate roof planes, and shade can change the installable layout. Treat the result as a planning range and compare it with a site-specific design before signing a proposal.
The calculation uses 29.61 cents/kWh from EIA Electric Power Monthly, Table 5.6.A — June 2026, reviewed 2026-09-04. The figure is a statewide residential average, not a promise about a particular utility account. It helps value solar energy used directly in the home, while exported energy is valued separately under the selected export assumption. A real bill can include fixed charges, seasonal pricing, time-of-use periods, minimum bills, taxes, and other terms that the statewide rate does not reproduce. Use the source-linked average for early comparison, then verify the exact tariff and recent usage history on the account before treating savings or payback as project-specific.
No incentive is subtracted from the default gross-cost estimate. SolarCalcNow requires an official or otherwise reviewable source, a review date, active status, eligibility rules, ownership conditions, and an explicit inclusion decision before a program can enter net-cost math. This prevents an expired, conditional, or third-party-only benefit from making a planning result look cheaper than the written project price. Review the state incentive page and the primary program source separately, confirm personal eligibility with qualified professionals, and keep each claimed credit or rebate on its own line when comparing proposals. Gross price, financing charges, battery cost, roof work, and incentives should not be collapsed into one unexplained number.
Massachusetts savings are rate-sensitive; net metering, program rules, and utility territory can change the value of excess production. Solar used immediately in the home is valued at the residential rate assumption, while exported energy is valued under the selected export scenario. If the export credit is below retail, a system designed for full annual usage offset can save less than a simple one-for-one net-metering model suggests, especially when much of its production leaves the home. The calculator therefore separates direct solar use from export and keeps the assumption editable. Confirm the serving utility, tariff, settlement period, fixed charges, rollover rules, and time-of-use treatment before relying on the modeled annual savings or simple payback.
The model combines user inputs with Massachusetts statewide rate, production, and cost assumptions, but it cannot inspect the property. It does not measure roof orientation, tilt, shade patterns, structural condition, usable roof planes, setbacks, electrical-service capacity, or interconnection constraints. It also cannot know the final equipment package, installer scope, financing fees, insurance requirements, utility tariff, or verified incentive eligibility. Those details can change panel count, production, gross cost, and payback. Use the result to understand scale and compare assumptions, then ask installers to document their site survey, production model, equipment, exclusions, and written price so differences can be traced rather than accepted as unexplained precision.
The current calculator does not geocode ZIP codes. It uses an author-selected reference point in the selected state, including when the optional live PVWatts provider responds. Entering a ZIP does not establish property-level accuracy. The model does not know the exact roof plane, azimuth, tilt, shade, setbacks or module layout. Check which production basis appears in the result, then compare it with the installer model and the physical roof survey before relying on annual output.