Maine Solar Savings Calculator

Pri Geens

Pri Geens

Maine Solar Savings Calculator

Maine Solar Savings Calculator

Calculate Maine solar costs, 2026 federal tax-credit status, net energy billing export tariffs, property and sales tax exemptions, payback period, and 25-year savings.

Maine 2026 rules: No state solar income tax credit. The federal Section 25D credit ended for systems placed in service after December 31, 2025. New systems receive net energy billing credits at a PUC-set tariff rate instead of full retail; legacy net metering customers remain grandfathered. Maine exempts solar equipment from property tax and sales tax.
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Estimates only. Verify utility rates, net energy billing tariff, tax exemptions, and federal tax status with your utility, installer, and tax professional.

What Is the Maine Solar Savings Calculator?

The Maine Solar Savings Calculator is a financial estimation tool that compares the upfront cost of a solar installation with the value of electricity generated over 25 years.

The calculator estimates how much a residential solar system costs, how much electricity it produces, when cumulative savings may recover the installation cost, and how much money could be saved over 25 years. It uses your electricity expenses, solar system capacity, installation price, utility export credits, and other entered assumptions.

The calculation separates electricity consumed directly by the household from electricity exported to the utility grid. These amounts can have different financial values because the retail electricity rate and export credit rate may differ.

The calculator also includes adjustable fields for federal and Maine tax credits, upfront rebates, annual solar utility fees, and property tax savings. Its results are estimates based on a fixed mathematical model, not guaranteed financial returns or confirmed incentive eligibility.

How the Maine Solar Savings Calculation Works

The calculator estimates installation costs, annual electricity production, and the financial value of solar energy. It then combines these figures to calculate payback time and 25-year net savings.

1. Calculate the Gross Solar System Cost

Gross installation cost depends on system capacity in kilowatts (kW) and the installed price per watt.

Gross Cost=System Size (kW)×1,000×Cost per Watt\text{Gross Cost}=\text{System Size (kW)}\times1{,}000\times\text{Cost per Watt}

The factor of 1,000 converts kilowatts into watts.

For example, an 8 kW system installed at $3.20 per watt has a gross cost of:

8×1,000×$3.20=$25,6008\times1{,}000\times\$3.20=\$25{,}600

2. Calculate the Net Installation Cost

The calculator subtracts entered federal and Maine credit amounts and upfront rebates from the gross installation cost.

Net Cost=max⁡(0, G−GF100−GM100−R)\text{Net Cost}=\max\left(0,\ G-\frac{GF}{100}-\frac{GM}{100}-R\right)

In this formula, G is gross installation cost, F is the entered federal credit percentage, M is the entered Maine credit percentage, and R is upfront rebates in dollars.

The net cost cannot fall below $0. Both credit percentages and the upfront rebate default to zero in the calculator’s 2026 setup.

Annual property tax savings are not subtracted from the upfront installation cost. Instead, the calculator adds that entered amount to each year’s financial savings.

3. Estimate Annual Solar Electricity Production

The calculator assumes each kilowatt of installed solar capacity produces 1,150 kilowatt-hours (kWh) of electricity during the first year.

Year 1 Production (kWh)=System Size (kW)×1,150\text{Year 1 Production (kWh)}=\text{System Size (kW)}\times1{,}150

For an 8 kW solar installation:

8×1,150=9,200 kWh8\times1{,}150=9{,}200\text{ kWh}

The model assumes electricity production decreases by 0.5% each year after the first year. This annual reduction is called solar degradation.

Py=1,150×S×(0.995)y−1P_y=1{,}150\times S\times(0.995)^{y-1}

Here, P represents annual electricity production, S is system capacity in kW, and y is the year being calculated.

The calculator distributes annual production across 12 months using fixed monthly percentages. These percentages total 100%, with more production assigned to certain months than others.

4. Estimate Household Electricity Consumption

The calculator estimates annual household electricity usage from your monthly electric bill and the entered retail electricity rate.

Annual Usage (kWh)=Monthly Electric Bill×12Electricity Rate ($/kWh)\text{Annual Usage (kWh)}=\frac{\text{Monthly Electric Bill}\times12}{\text{Electricity Rate (\$/kWh)}}

For a $160 monthly bill and a $0.25/kWh electricity rate:

160×120.25=7,680 kWh\frac{160\times12}{0.25}=7{,}680\text{ kWh}

The calculator divides estimated annual consumption equally across 12 months. The electricity rate must be greater than zero for this calculation to produce a meaningful result.

5. Calculate Annual Solar Electricity Savings

The calculator separates monthly solar electricity into two categories:

  • Self-consumed electricity: Solar electricity used directly by the household, valued at the entered retail electricity rate.
  • Exported electricity: Remaining solar electricity sent to the grid, valued at the entered export credit rate.

Monthly self-consumption is limited to the smaller of the selected self-consumption share of monthly production or estimated monthly household electricity usage. All remaining modeled production is classified as exported electricity.

Annual Savingsy=∑m=112(Dy,m×ry+Ey,m×ey)−A+T\text{Annual Savings}_y=\sum_{m=1}^{12}(D_{y,m}\times r_y+E_{y,m}\times e_y)-A+T

In this formula, D is directly consumed electricity, E is exported electricity, r is the retail electricity rate, e is the export credit rate, A is annual utility solar fees, and T is annual property tax savings.

The calculator increases both electricity rates each year using the entered annual utility rate increase percentage. Annual fees and property tax savings remain fixed at their entered dollar amounts.

6. Determine Payback and 25-Year Net Savings

The calculator adds annual savings over 25 years and subtracts the net installation cost.

25-Year Net Savings=∑y=125Annual Savingsy−Net Cost\text{25-Year Net Savings}=\sum_{y=1}^{25}\text{Annual Savings}_y-\text{Net Cost}

The payback period is the first whole modeled year when cumulative savings equal or exceed the net installation cost.

If the net cost is $0, the calculator displays “Immediate.” If cumulative savings do not cover the installation cost within 25 years, it displays “25+ Years.”

Worked Example: An 8 kW Maine Solar System

Consider a hypothetical solar installation using the calculator’s default input values:

  • Monthly electric bill: $160
  • Retail electricity rate: $0.25/kWh
  • Solar system size: 8 kW
  • Installed cost: $3.20 per watt
  • Export credit: $0.09/kWh
  • Daytime self-consumption: 30%
  • Annual utility rate increase: 4%
  • Annual property tax savings: $100
  • Federal credit, Maine credit, upfront rebates, and annual solar fees: $0

The gross and net installation costs are both $25,600. Estimated first-year production is 9,200 kWh, with 2,760 kWh used directly and 6,440 kWh exported.

First-year electricity savings are calculated as follows:

(2,760×0.25)+(6,440×0.09)=$1,269.60(2{,}760\times0.25)+(6{,}440\times0.09)=\$1{,}269.60

Adding $100 in annual property tax savings gives total first-year modeled savings of $1,369.60.

After applying the annual production decline and electricity rate increases, cumulative savings reach approximately $51,819 over 25 years.

Subtracting the $25,600 net installation cost produces approximately $26,219 in 25-year net savings. The modeled installation reaches its payback period in Year 15.

These figures illustrate the calculator’s assumptions. They are not guaranteed savings for an actual Maine home.

How to Use the Maine Solar Savings Calculator

Follow these steps to estimate your solar installation costs and long-term savings.

  1. Enter your monthly electric bill. Provide your electricity expense in dollars. The starting value is $160.
  2. Enter your electricity rate. Type your retail electricity price in dollars per kWh. The default is $0.250/kWh.
  3. Enter your solar system size. Specify the proposed system capacity in kW. The default is 8 kW.
  4. Enter the installed cost per watt. Use an installation quote or another price assumption. The starting value is $3.20 per watt.
  5. Select your utility. Choose Central Maine Power (CMP), Versant Power, Cooperative or Municipal, or Other Utility.
  6. Enter the export credit rate. Provide the dollar amount assumed for each exported kWh. The default is $0.090/kWh.
  7. Adjust daytime self-consumption. Enter a percentage from 0% to 100%. The starting value is 30%.
  8. Enter the annual utility rate increase and fees. The calculator starts with a 4% annual rate increase and $0 in annual solar fees.
  9. Review the battery option and incentives. The form includes a battery storage or high daytime self-use checkbox, tax-credit fields, upfront rebates, and annual property tax savings. The battery checkbox does not itself change the calculation.
  10. Click “Calculate Savings.” Review the net installation cost, payback period, 25-year savings, and production estimates.
  11. Click “Reset” to start again. This restores the original field values and hides the previous results.

The main results are Payback Period and 25-Year Net Savings. The first measures how long modeled savings take to recover installation costs. The second shows cumulative savings remaining after subtracting net installation cost.

Understanding Your Maine Solar Savings Results

The calculator provides several financial and electricity production estimates. Understanding their meaning helps you compare different input scenarios.

Gross System Cost and Net Cost

Gross System Cost represents the installation price before deductions. Federal Credit, State Credit, and Rebates show the amounts calculated from your entered incentive values. Net Cost is the remaining installation expense after those deductions, with a minimum of $0.

Payback Period

Payback Period identifies the first modeled year when cumulative savings cover the net installation cost. The result is displayed in whole years, rather than exact months or days.

The accompanying progress meter compares the payback timeline with the calculator’s 25-year period.

25-Year Net Savings

This result represents estimated cumulative financial savings after subtracting the net system cost. A positive figure means cumulative modeled savings exceed installation cost. A negative figure indicates that the initial cost has not been fully recovered after 25 years.

Year 1 Production and Annual Usage

Year 1 Production shows estimated first-year solar generation in kWh. Annual Usage shows estimated household electricity consumption based on the entered monthly bill and electricity rate.

The calculator displays electricity quantities as whole kWh and system capacity to one decimal place.

Solar Offset Percentage

Solar Offset compares first-year solar electricity production with estimated annual household usage.

Solar Offset (%)=Year 1 Solar ProductionAnnual Household Usage×100\text{Solar Offset (\%)}=\frac{\text{Year 1 Solar Production}}{\text{Annual Household Usage}}\times100

In the default example, 9,200 kWh divided by 7,680 kWh produces a displayed solar offset of 120%.

This does not mean the household uses 120% of its electricity directly from solar panels. It means estimated annual solar generation is approximately 120% of estimated annual electricity consumption. The formula does not cap the result at 100%.

25-Year CO2 Offset

The calculator also estimates a carbon dioxide offset using cumulative solar electricity production and a fixed conversion factor of 0.45 tons per 1,000 kWh.

CO2 Offset (tons)=25-Year Production (kWh)1,000×0.45\text{CO2 Offset (tons)}=\frac{\text{25-Year Production (kWh)}}{1{,}000}\times0.45

For the default scenario, the calculator produces approximately 97.5 tons of estimated CO2 offset over 25 years.

This is a simplified environmental estimate based on solar generation. It does not calculate actual changes in utility emissions over time.

Important Note About the Year 1 Result Labels

Three displayed result labels in the current calculator do not match the values supplied by its calculation code.

The rows labeled “Year 1 Self-Use kWh” and “Year 1 Export kWh” receive the modeled values from Year 25 rather than Year 1. The row labeled “Net Year 1 Savings” displays the positive portion of 25-year net savings, or $0 when that amount is negative.

With the default inputs, those rows display approximately 2,447 kWh, 5,710 kWh, and $26,219. The underlying first-year values are 2,760 kWh directly used, 6,440 kWh exported, and $1,369.60 in modeled financial savings.

The separate Payback Period, 25-Year Net Savings, and Year 1 Production results follow their corresponding calculations.

Factors That Affect Solar Savings in Maine

Solar Installation Price and System Size

A larger solar system produces more estimated electricity. It also raises upfront installation cost when the installed price per watt stays unchanged.

The calculator begins with an 8 kW installation and a $3.20-per-watt price. You can change these values to compare hypothetical installation sizes and costs.

Retail Electricity Rates and Export Tariffs

The calculator assigns the retail electricity rate to directly consumed solar power and the entered export credit rate to electricity sent to the grid.

The default retail rate is $0.25/kWh, while the export rate is $0.09/kWh. Under these assumptions, directly used electricity has a higher modeled financial value than exported electricity.

The calculator’s Maine guidance describes net energy billing and different arrangements for legacy net metering customers. However, the calculation itself uses one manually entered export rate. Selecting CMP, Versant Power, or another utility does not automatically apply a different tariff.

The actual export credit and applicable billing terms should be verified with the electricity provider.

Daytime Self-Consumption

The daytime self-consumption percentage controls how much modeled solar electricity may be valued at the retail rate rather than the export rate. Direct consumption is also limited by estimated monthly household electricity usage.

The battery storage or high daytime self-use checkbox does not automatically adjust self-consumption or add battery costs. To test a different self-consumption assumption, change the percentage field directly.

Annual Electricity Rate Increases

The calculator applies the entered annual rate increase to both retail electricity prices and export credits. The default increase is 4% per year.

A higher entered increase generally raises the future value of solar electricity, while the model simultaneously reduces production by 0.5% annually.

These are fixed calculation assumptions, not predictions of actual future electricity prices or solar performance.

Tax Credits, Rebates, and Property Tax Savings

The calculator includes federal and Maine tax-credit fields, upfront rebates, and annual property tax savings.

Its 2026 guidance states that the residential Section 25D credit ended for systems placed in service after December 31, 2025, and identifies no Maine state solar income tax credit. Both percentage fields therefore default to 0%.

The calculator’s guidance also describes Maine solar equipment property and sales tax exemptions. Its property tax savings field starts at $100 per year, which the calculation adds to annual financial savings. The model does not separately calculate sales tax savings.

These descriptions and default assumptions are not a determination of tax eligibility. Verify applicable tax treatment and incentives before including them in a financial plan.

Expenses Not Separately Modeled

The calculator includes entered annual utility solar fees but does not separately calculate loan interest, financing payments, maintenance costs, battery replacement, or other equipment replacement expenses.

Real installation costs and long-term financial returns may differ because of these expenses and other household or equipment conditions.

Frequently Asked Questions

How much money can solar panels save in Maine?

Estimated savings depend on installation costs, electricity rates, export credits, system capacity, and other inputs. Using its default 8 kW scenario, the calculator estimates approximately $26,219 in net savings over 25 years. This is a hypothetical calculation based on the model’s assumptions, not an average or guaranteed savings amount for Maine homeowners.

How long does it take for solar panels to pay for themselves in Maine?

The calculator determines payback by identifying the first year when cumulative savings equal or exceed the net installation cost. With its default inputs, payback occurs in Year 15. The result changes when installation costs, electricity rates, export credits, or other assumptions change. Payback is reported in whole years.

Does the calculator include Maine net energy billing?

The calculator accounts for exported electricity by applying the export credit rate entered by the user. It includes utility selections for Central Maine Power, Versant Power, and other providers, but these choices do not automatically change the calculation. The model does not independently verify eligibility or apply utility-specific credit settlement rules.

Can I include property tax savings in the calculation?

Yes. The calculator includes an annual property tax savings field, initially set to $100. The entered amount is added to each year’s modeled financial savings over the 25-year period. It does not calculate your actual property tax bill or determine whether a specific installation qualifies for an exemption.

Why can the solar offset percentage exceed 100%?

Solar Offset compares estimated first-year solar generation with estimated annual household electricity usage. If generation exceeds usage, the ratio can be greater than 100%. For example, the default scenario produces a 120% offset. This does not mean the household directly consumes all that electricity or eliminates every utility charge.

Does the calculator account for solar panel degradation?

Yes. The calculator assumes solar electricity production decreases by 0.5% annually after Year 1. This assumption affects modeled electricity generation, financial savings, and cumulative CO2 offset throughout the 25-year period. Actual panel performance may differ from this fixed degradation assumption.

Is the Maine solar savings estimate guaranteed?

No. The calculator provides a mathematical estimate based on entered financial values and fixed production assumptions. Actual savings may differ because of weather, shading, installation prices, electricity tariffs, maintenance expenses, taxes, and equipment performance. Use the results for scenario planning rather than as a guaranteed financial return.

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