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Solar + Heat Pump Combined Savings Calculator

Switching from gas, oil, or propane to a heat pump plus solar? Enter your current fuel cost and system sizes — get combined annual savings, payback period, and CO2 reduction.

Current heating setup
$
sq ft
Heat pump & solar
$/kWh
kW
Combined heat pump + solar savings
$746/yr total savings — 30.6 yr payback
Heat pump annual electricity use6,252 kWh/yr
Heat pump annual electricity cost$813/yr
Fuel savings from heat pump$387/yr
Solar offset of heat pump electricity$359/yr
Solar panels needed15 × 400W panels
Heat pump cost (est.)$6,000
Solar system cost (est.)$16,800
Total package cost$22,800
CO2 reduction6,356 lbs/yr
Annual heating cost comparison
Status quo (current fuel)$1,200/yr
Heat pump alone (no solar)$813/yr
Heat pump + solar (this scenario)$454/yr
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How to Use This Calculator

Enter your current heating fuel and cost

Select your current heating fuel type — natural gas, fuel oil, propane, or electric resistance. Enter your total annual heating cost in dollars (sum your utility bills for the heating months, or check your annual usage summary). The calculator uses average fuel prices to estimate your BTU consumption, then converts that to heat pump electricity requirements using the COP (Coefficient of Performance).

Choose your heat pump and solar size

Air Source Heat Pumps (ASHP) are the most common — they extract heat from outdoor air even in cold weather and cost $4,000-$8,000 installed. Ground Source Heat Pumps (GSHP) extract heat from the earth and are more efficient (COP 4.5 vs 3.0) but cost $15,000-$25,000. The solar system size entry lets you size an array specifically to offset your heat pump's electricity use — enter 5-10 kW depending on your climate and consumption.

Read the three-way comparison

The comparison table shows three scenarios: staying on current fuel (status quo), switching to heat pump only, and heat pump plus solar. For most oil and propane customers, the fuel savings from switching to a heat pump are so large that the combination pays back in 4-8 years even accounting for the full package cost.

The Formula

Annual BTU from fuel = Annual Units (therms/gallons/kWh) × BTU per unit Heat delivered = Annual BTU × Furnace efficiency (80% fossil, 100% electric) Heat pump kWh = Heat delivered BTU ÷ (COP × 3,412 BTU/kWh) Heat pump annual cost = Heat pump kWh × Electricity rate Fuel savings = Current fuel cost − Heat pump annual cost Solar production = Solar kW × 1,000 × 4.5 PSH × 365 × 0.80 Solar for heat pump = Solar production × 35% (heat pump daytime share) Solar offset value = Solar for heat pump kWh × Electricity rate Combined savings = Fuel savings + Solar offset value Package payback = (Heat pump cost + Solar cost) ÷ Combined savings

The COP (Coefficient of Performance) is the key heat pump metric: a COP of 3.0 means for every 1 kWh of electricity input, the heat pump delivers 3 kWh of heat. An ASHP's COP varies with outdoor temperature — it's higher in mild weather (COP 4+) and drops in very cold weather (COP 2-2.5 below 20°F). The 3.0 average used here is a conservative seasonal average for Zone 3-4 climates. GSHP's earth-loop maintains stable COP 4.0-5.0 regardless of outside temperature.

Example

The Thompson family — Gas furnace to ASHP + Solar in Denver

The Thompsons have a 2,000 sq ft home in Denver (Zone 3) with a gas furnace. They spend $1,200/year on natural gas for heating and pay $0.13/kWh for electricity. They're considering switching to an air source heat pump and adding a 6 kW solar array.

Current fuelNatural gas, $1,200/yr
Heat pump typeASHP (COP 3.0)
Solar array6 kW
Electricity rate$0.13/kWh

Result

Heat pump electricity use~3,400 kWh/yr
Heat pump annual cost~$440/yr
Fuel savings~$760/yr
Solar offset value~$310/yr
Combined annual savings~$1,070/yr
Total package cost~$22,800 (HP $6K + Solar $16.8K)
Payback period~21 years

For the Thompsons, the economics work best for the heat pump standalone (payback ~7 years), while adding solar extends payback. However, if they also need solar for household electricity — typical for a home of this size — the combined package makes more sense as a single project. The CO2 reduction of over 2,000 lbs/year and the energy independence are significant additional benefits. Oil and propane customers with $2,500-$4,000/year fuel bills see dramatically better payback periods of 4-8 years.

FAQ

Modern cold-climate heat pumps work effectively down to -15°F or even -22°F, though efficiency (COP) decreases as temperatures drop. In Zone 4-5 climates like Chicago and Boston, look for heat pumps rated for cold climates: Mitsubishi Hyper Heat, Bosch Compress 3000, Carrier Infinity, and Daikin Fit all maintain heating output at 0°F. Most homes keep a small electric backup strip heater (already built into the air handler) for extreme cold snaps. Ground source heat pumps avoid cold weather COP degradation entirely since ground temperature stays stable at 50-55°F year-round.
COP (Coefficient of Performance) measures heat pump efficiency: COP 3.0 means 3 kWh of heat delivered per 1 kWh of electricity input — effectively 300% efficiency. This is possible because heat pumps move heat rather than generate it. Compare this to electric resistance heating (COP 1.0 — 100% efficient, converts all electricity to heat) and a high-efficiency gas furnace (AFUE 96% — can't exceed 100%). A heat pump with COP 3.0 delivers the same heat as electric resistance at one-third the electricity cost. In mild weather, ASHP COP can reach 4-5; in very cold weather it drops to 1.5-2.5.
The most financially compelling solar + heat pump combination is propane or oil heating → ASHP + solar. Propane and oil users often pay $3,000-5,000/year for heating fuel; switching to an ASHP reduces that to $600-1,200/year in electricity. Solar then offsets 30-50% of that electricity cost. The combined savings of $2,500-4,000/year produce payback periods of 5-9 years for the full package. Natural gas customers see smaller savings because gas is cheaper per BTU, so the economics are tighter (payback 12-20 years). Electric resistance customers see good savings too — their electricity bills are high and ASHP cuts usage by 65-70%.
Yes — multiple federal incentives apply to heat pumps in 2026 under the Inflation Reduction Act: 25C Energy Efficient Home Improvement Credit: 30% credit on ASHP costs, up to $2,000/year for the heat pump itself. Residential Clean Energy Credit (also 30%): covers the solar system. High-Efficiency Electric Home Rebate Act (HEEHRA): up to $8,000 upfront rebate for heat pump installation for low-to-moderate income households, administered through state programs. Many states and utilities add their own rebates on top — the ENERGY STAR rebate finder at energystar.gov lists all available incentives by zip code.
Installing both together has several advantages: (1) Right-sizing the solar system — knowing your heat pump's electricity consumption lets you size solar precisely for your total load. Installing solar first and adding a heat pump later often means the original solar system is undersized. (2) Single installation cost — one set of permit fees, one electrical panel upgrade if needed, and possible installer discounts for bundled projects. (3) Combined financing — many lenders offer better rates for combined energy projects. The main reason to stagger them: if you can't afford both at once, the heat pump typically provides faster payback and should come first.

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