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The "Watch City" on the Route 128 tech corridor with ~64,000 residents and diverse housing from suburban ranches to downtown triple-deckers. Eversource territory at $0.2836/kWh. SMART 3.0 + ConnectedSolutions make Waltham an excellent solar market.
Eversource territory • SMART 3.0 • ConnectedSolutions eligible • Route 128 corridor
2026 Reality: The 30% federal tax credit (Section 25D) expired for homeowners December 31, 2025. All costs in this guide reflect $0 federal credit. Full details
An 11 kW solar system in Waltham costs $33,550-$37,400 in 2026. In Eversource territory at $0.2836/kWh, with SMART income of ~$396/yr and full retail net metering, the investment pays for itself in 7-8.5 years and generates ~$120,000 in savings over 25 years.
Cost Range
$3.05-$3.4/W
Fully installed
Avg System
11 kW
Waltham average
Payback
7-8.5 yrs
Cash purchase
25-Year Savings
~$120K
Estimated total value
Waltham is a diverse city of ~64,000 residents straddling the Route 128 tech corridor. Known historically as the Watch City, it features a broad mix of housing -- from post-war suburban ranches to downtown triple-deckers -- at more affordable prices than neighboring Newton or Lexington.
Population
~64,000
Median Home Value
~$680,000
Primary Utility
Eversource
Electric Rate
$0.2836/kWh
Typical System Size
9-14 kW
Solar Irradiance
4.2 kWh/m²/day
Costs for different system sizes in Waltham at $3.05-3.40/W. Waltham homes range from condos and smaller ranches (7-9 kW) to larger colonials with EV charging needs (14-17 kW).
| System Size | Low Cost | High Cost | SMART 3.0 | Best For |
|---|---|---|---|---|
| 7 kW | $21,350 | $23,800 | ~$252/yr | Condo / smaller ranch |
| 9 kW | $27,450 | $30,600 | ~$324/yr | Mid-size colonial or cape |
| 11 kW | $33,550 | $37,400 | ~$396/yr | Typical Waltham single-family |
| 14 kW | $42,700 | $47,600 | ~$504/yr | Large home / EV + battery |
| 17 kW | $51,850 | $57,800 | ~$612/yr | High usage / multi-zone HVAC |
Prices include equipment, labor, permits, and grid interconnection. No federal tax credit included (expired). $1,000 MA state tax credit not deducted.
Waltham's neighborhoods range from dense downtown areas to spacious suburban lots along the Route 128 corridor. Here is how solar conditions vary across the city.
Home Types
Ranches, split-levels, 1950s-70s colonials
Avg System
10-13 kW
Post-war suburban housing with great roof access. Larger lots, fewer mature trees. Many tech workers from the Route 128 corridor choosing solar. Excellent solar candidates.
Home Types
Capes, colonials, newer construction
Avg System
10-12 kW
Residential neighborhoods with well-maintained homes and good south-facing roof exposure. Family-oriented areas with strong solar adoption rates.
Home Types
Multi-family, triple-deckers, mixed-use
Avg System
8-10 kW
Denser housing near downtown. Triple-deckers and multi-family buildings can work well for shared solar. Some buildings may benefit from community solar instead.
Home Types
Victorians, colonials, older homes
Avg System
9-12 kW
Historic area with mature tree canopy. Larger older homes with high electricity bills. Some shading challenges but microinverters handle partial shade well.
Waltham's Building Department handles solar permits. The process typically takes 2-3 weeks. Waltham is generally straightforward for residential solar installations.
Installer evaluates roof condition, shading, orientation, and structural integrity. Neighborhood-specific factors (tree canopy, roof age) identified.
Application to Waltham Building Department with electrical and structural plans. Standard residential solar permit process.
Typical installation 1-3 days. Electrical and building inspection by the City of Waltham.
Eversource approves grid connection. 2-4 weeks. Net metering activated once approved.
Massachusetts offers one of the strongest solar incentive packages in the country. Here is what Waltham homeowners can stack.
$0.03/kWh for all electricity produced for 20 years. An 11 kW system generates ~$396/yr in SMART income.
~$396/yr
~$7,500 over 20 years
1:1 credit at full retail rate of $0.2836/kWh. Credits roll over monthly and true up in April.
~$3,742/yr
Annual electricity savings (11 kW)
Eversource demand response. Earn $275/kW summer + $50/kW winter for discharging your battery during peak events.
$3,250/yr
Typical 10 kW battery
15% of system cost, capped at $1,000. Claimed on your MA state tax return.
$1,000
One-time credit
Solar systems are exempt from the 6.25% MA sales tax. Immediate savings at purchase.
~$2,222
Savings on typical system
Solar-added value is exempt from property tax for 20 years. Saves annually based on local tax rate.
~$349/yr
20-year exemption (~$6,980 total)
Section 25D (the 30% residential solar tax credit) expired December 31, 2025 under the OBBBA. Waltham homeowners buying cash or loan receive $0 in federal credit. However, third-party system owners (PPA/lease) can still claim the commercial Section 48/48E ITC -- which translates to lower PPA rates for you.
Read: What happened to the solar tax creditThree ways to pay for solar in Waltham. PPAs offer $0 down because the third-party system owner claims the commercial Section 48 ITC.
Upfront
~$33,550-$37,400
Monthly
$0
25-yr Savings
~$120K
Ownership
You own it
Best long-term ROI. 7-8.5 year payback. Full SMART income + net metering yours.
Upfront
$0 down
Monthly
~$230-320/mo (5.5-8% APR)
25-yr Savings
~$75-95K
Ownership
You own it
10-25 year terms through local lenders and credit unions. SMART income + net metering offset monthly payments.
Upfront
$0
Monthly
Fixed ~$0.14-0.18/kWh
25-yr Savings
~$30-45K
Ownership
Third party owns
Third-party owner claims Section 48 ITC. You buy power at a discount. Immediate savings.
Waltham has a significant renter population and many multi-family buildings near downtown. Community solar is an excellent alternative for those who cannot install panels on their own roof.
Savings
10-20%
On electricity bill
Upfront Cost
$0
No installation
Contract
Flexible
Cancel anytime
How Waltham solar costs compare to neighboring communities. All are in Eversource territory with access to the same state incentives.
| City/Town | Cost/W | Avg System | Utility | Notes |
|---|---|---|---|---|
| Waltham | $3.05-3.40 | 11 kW | Eversource | Route 128 corridor, diverse housing, affordable entry point |
| Newton | $3.10-3.45 | 11.5 kW | Eversource | 13 villages, higher home values, slightly higher costs |
| Lexington | $3.10-3.45 | 12 kW | Eversource | Affluent suburb, large colonials |
| Watertown | $3.05-3.40 | 9 kW | Eversource | Denser, smaller lots, more multi-family |
| Belmont | $3.10-3.45 | 11 kW | Eversource | Similar market, slightly higher values |
Solar panels in Waltham cost $3.05-3.40 per watt installed in 2026. A typical 11 kW system costs $33,550-$37,400 before MA state incentives. The federal Section 25D residential tax credit expired December 31, 2025 -- homeowners receive $0 in federal credit. Massachusetts state incentives (SMART 3.0, net metering, state tax credit, and tax exemptions) still make solar highly profitable in Waltham.
Yes. Waltham is excellent for solar. It sits in Eversource territory at $0.2836/kWh (among the highest in the US), has SMART 3.0 income ($396/yr for an 11 kW system), and 1:1 net metering. The city has a mix of housing stock from the Route 128 corridor suburban homes (ideal for solar) to multi-family near downtown. Waltham also has a more affordable entry point than neighboring Newton or Lexington, making the payback period competitive at 7-8.5 years.
SMART 3.0 (Solar Massachusetts Renewable Target) pays solar system owners $0.03/kWh for all electricity produced, locked in for 20 years. An 11 kW system in Waltham generates approximately $396/year in SMART income, totaling roughly $7,500 over the program duration. Low-income households qualify for $0.06/kWh (double rate). Battery storage adds $0.04/kWh on top.
ConnectedSolutions is Eversource's demand response program for battery owners. During peak grid events (primarily summer), you discharge your battery to the grid and earn $275/kW in summer and $50/kW in winter. A typical 10 kW home battery can earn $2,750 in summer plus $500 in winter, totaling $3,250/year. Waltham is in Eversource territory, which offers the highest ConnectedSolutions rates in MA.
Yes. Even without the expired 25D federal credit, Waltham solar pays back in 7-8.5 years thanks to high Eversource electricity rates ($0.2836/kWh), SMART 3.0 income, and 1:1 net metering. Over 25 years, a typical system saves approximately $120,000. The 20-year property tax exemption saves an additional ~$349/year, and the $1,000 MA state tax credit helps offset costs in year one.
We will assess your specific roof, neighborhood conditions, and Eversource rate to show you exactly what solar costs and saves for your Waltham home -- including SMART 3.0 and ConnectedSolutions.
Complete guide to solar in Massachusetts.
Read moreStatewide solar costs and city-by-city breakdown.
Read more$0.03/kWh for 20 years. How to enroll and earn.
Read moreEarn $225-$1,500/yr per battery.
Read moreMetroWest neighbor. $3.00-3.35/W.
Read moreMetroWest solar. $3.05-3.40/W.
Read more25D expired. What options remain.
Read moreCompare utility rates, net metering, and solar economics.
Read moreTrack rate changes across MA utilities since 2020.
Read moreLive installation data, capacity trends, and market stats.
Read moreCurrent wait times, bottlenecks, and how to get connected faster.
Read morePricing: EnergySage Solar Marketplace (January 2026), NuWatt Energy Greater Boston installations.
Utility rates: Eversource residential rate schedule RS, effective February 2026.
SMART 3.0: MassDOER / MassCEC, SMART program guidelines PY2026.
ConnectedSolutions: Eversource demand response program rates, 2026 season.
Tax exemptions: MA Department of Revenue, Waltham Assessor data.