How many watts does a heat pump use?

A heat pump uses between 500 watts (1-ton mini-split) and 6,000 watts (5-ton ducted system) during normal operation. The exact wattage depends on the type, size (tonnage), operating mode, and efficiency rating. Mini-splits use the least power per ton, geothermal systems are the most efficient overall, and standard ducted air-source heat pumps fall in between.

What is the difference between running watts and surge watts for a heat pump?

Running watts (also called rated watts) is the continuous power a heat pump draws during normal operation. Surge watts (also called starting watts or locked rotor amps) is the brief spike of power needed when the compressor starts, typically 3 to 5 times the running wattage. Surge watts last only 0.5 to 2 seconds. This distinction matters when sizing generators, inverters, and solar battery systems.

Does a heat pump use more watts in heating mode or cooling mode?

In moderate conditions, heating and cooling modes use similar wattage. However, when outdoor temperatures drop below 30 to 35 degrees F, an air-source heat pump works much harder and can use 30 to 50 percent more electricity than in cooling mode. At very low temperatures, the system may engage auxiliary electric resistance heat strips, which add 5,000 to 15,000 watts. Geothermal systems avoid this problem because ground temperatures remain stable year-round.

How many solar panels do I need for a 3-ton heat pump?

A 3-ton ducted heat pump uses about 3,000 to 3,500 watts running, which translates to roughly 10.8 kWh per day at 8 hours of operation with a 45 percent duty cycle. At 5 peak sun hours with 400W panels and an 0.83 derate factor, you need about 7 panels. In cloudier regions with 4 peak sun hours, plan for 9 panels.

What does SEER and HSPF mean for heat pump wattage?

SEER (Seasonal Energy Efficiency Ratio) measures cooling efficiency -- higher SEER means fewer watts per BTU of cooling. HSPF (Heating Seasonal Performance Factor) measures heating efficiency the same way. A 16 SEER heat pump uses roughly 25 percent less electricity than a 12 SEER unit for the same cooling output. Current federal minimums are 15 SEER2 and 8.8 HSPF2 for heat pumps.

How do I read the wattage on my heat pump's nameplate?

Your heat pump's nameplate is on the outdoor condenser unit. Look for RLA (Rated Load Amps) and voltage. Multiply RLA by voltage to get approximate running watts. For example, 15 RLA at 240V equals 3,600 watts. Also look for LRA (Locked Rotor Amps), which indicates surge watts. MCA (Minimum Circuit Ampacity) tells you the minimum wire size, and MOP (Maximum Overcurrent Protection) tells you the required breaker size.

Are geothermal heat pumps more efficient than air-source heat pumps?

Yes. Geothermal heat pumps are 30 to 60 percent more efficient than air-source units because they exchange heat with the stable ground temperature (50 to 60 degrees F year-round) rather than outdoor air. A geothermal system rated at 30 EER uses roughly half the watts per ton compared to a standard air-source unit rated at 15 SEER. The trade-off is significantly higher installation cost due to ground loop drilling or trenching.

Can a solar system handle a heat pump's startup surge?

Grid-tied solar systems handle surge watts without issue because the grid absorbs the momentary spike. Off-grid systems need an inverter rated for the surge wattage, typically 3 to 5 times the running watts. For a 3-ton heat pump (3,500W running), you need an inverter that handles at least 10,500 to 17,500 watts surge. Many modern heat pumps use variable-speed compressors with soft-start technology that reduces the surge to only 1.5 to 2 times running watts.

Heat Pump Wattage Chart: How Many Watts By Size And Type (2026)

Heat pump wattage ranges from 500W for a small mini-split to over 6,000W for a 5-ton ducted system. Knowing the exact number matters when you are sizing a solar array, choosing a generator for backup, or selecting an inverter for off-grid use. This chart covers every common type and size, plus the startup surge that catches many people off guard.

Heat Pump Wattage Chart By Type And Tonnage

The table below shows typical running watts for the three main heat pump types across standard residential sizes. All values assume cooling mode at moderate outdoor temperatures and units meeting current federal efficiency minimums.

Size	BTU/hr	Mini-Split (Running W)	Ducted Air-Source (Running W)	Geothermal (Running W)
1 ton	12,000	500 - 800	900 - 1,200	400 - 700
1.5 ton	18,000	750 - 1,100	1,200 - 1,700	600 - 1,000
2 ton	24,000	1,000 - 1,500	1,600 - 2,200	800 - 1,300
2.5 ton	30,000	1,200 - 1,800	2,000 - 2,800	1,000 - 1,600
3 ton	36,000	1,500 - 2,200	2,500 - 3,500	1,200 - 2,000
3.5 ton	42,000	1,800 - 2,600	3,000 - 4,000	1,500 - 2,300
4 ton	48,000	2,200 - 3,000	3,500 - 4,800	1,800 - 2,800
5 ton	60,000	2,800 - 3,800	4,500 - 6,000	2,200 - 3,500

Source: ENERGY STAR certified product data and AHRI Directory of Certified Product Performance. Actual wattage varies by SEER/HSPF rating, outdoor temperature, and refrigerant charge.

Startup (Surge) Watts By Heat Pump Size

When a heat pump compressor kicks on, it draws a brief but significant surge of power. This matters for generator sizing, inverter sizing, and breaker selection.

Size	Running Watts (Ducted)	Surge Watts (Standard Start)	Surge Watts (Soft Start)
1 ton	900 - 1,200	2,700 - 6,000	1,350 - 2,400
1.5 ton	1,200 - 1,700	3,600 - 8,500	1,800 - 3,400
2 ton	1,600 - 2,200	4,800 - 11,000	2,400 - 4,400
3 ton	2,500 - 3,500	7,500 - 17,500	3,750 - 7,000
4 ton	3,500 - 4,800	10,500 - 24,000	5,250 - 9,600
5 ton	4,500 - 6,000	13,500 - 30,000	6,750 - 12,000

Standard compressors draw 3 to 5 times their running watts on startup for about 0.5 to 2 seconds. Variable-speed and inverter-driven compressors (common in mini-splits and newer ducted systems) ramp up gradually, reducing surge to about 1.5 to 2 times running watts.

Heating Mode vs Cooling Mode Wattage

Heat pumps are unique because they both heat and cool. The power draw changes depending on which mode they are running and how extreme the outdoor temperature is.

Condition	Wattage Impact
Cooling mode, 85-95 degrees F outdoors	Baseline running watts (values in chart above)
Cooling mode, over 100 degrees F outdoors	10-20% above baseline
Heating mode, 30-50 degrees F outdoors	Similar to cooling baseline
Heating mode, 10-30 degrees F outdoors	20-40% above cooling baseline
Heating mode, under 10 degrees F outdoors	30-50% above baseline, may trigger aux heat
Auxiliary heat strips engaged	Add 5,000 to 15,000W depending on strip size

The auxiliary heat strips are electric resistance heaters built into the air handler. They activate when the heat pump alone cannot maintain the set temperature. A single strip is typically 5 kW (5,000W), and many systems have two or three strips. When aux heat is running, your power consumption can triple or quadruple compared to normal heat pump operation.

This is why solar sizing for a heat pump in cold climates should account for aux heat -- or better yet, consider a geothermal system that rarely needs it.

Understanding SEER, HSPF, And Their Effect On Wattage

Efficiency ratings directly determine how many watts your heat pump draws for a given amount of heating or cooling output.

SEER2 (Seasonal Energy Efficiency Ratio 2) measures cooling efficiency. It equals total BTU of cooling divided by total watt-hours of electricity over a cooling season. A 16 SEER2 system uses 750 watt-hours to produce 12,000 BTU, while a 20 SEER2 system uses only 600 watt-hours for the same output -- a 20% reduction in electricity.

HSPF2 (Heating Seasonal Performance Factor 2) measures heating efficiency the same way. The current federal minimum is 8.8 HSPF2. High-efficiency units reach 13 HSPF2 or higher.

EER (Energy Efficiency Ratio) is similar to SEER but measured at a single test condition (95 degrees F outdoors). Geothermal systems use EER because they are not affected by outdoor air temperature. A geothermal unit rated at 25-30 EER is roughly twice as efficient as a 15 SEER air-source unit.

Rating	Watts per Ton (Cooling)	Relative Efficiency
14 SEER2 (minimum for most regions)	857	Baseline
16 SEER2	750	12% better
18 SEER2	667	22% better
20 SEER2	600	30% better
25 EER (geothermal)	480	44% better

How To Read Your Heat Pump's Nameplate

Every heat pump has a data plate on the outdoor unit (condenser) with the electrical specifications you need for solar sizing. Here is what each number means:

Model number -- Often encodes the tonnage. Look for "24" (2 ton), "36" (3 ton), "48" (4 ton), or "60" (5 ton) in the model string. These correspond to thousands of BTU/hr.
RLA (Rated Load Amps) -- The current draw during normal operation. Multiply by voltage for running watts: 15 RLA at 240V = 3,600W.
LRA (Locked Rotor Amps) -- The surge current at compressor startup. Multiply by voltage for surge watts: 75 LRA at 240V = 18,000W surge.
MCA (Minimum Circuit Ampacity) -- The minimum wire gauge your electrician should use.
MOP (Maximum Overcurrent Protection) -- The maximum breaker size.
Voltage/Phase -- Residential units are almost always 208-230V, single phase, 60 Hz.

To find your actual running watts with precision, use a clamp meter on the circuit while the system is running. Nameplate RLA is a maximum rated value -- actual draw is often 70 to 85 percent of nameplate under normal conditions.

Solar Panel Sizing For Each Heat Pump Size

The following table shows how many 400W solar panels you need to offset the electricity used by each heat pump size. Assumptions: 8 hours of operation per day, 45% duty cycle (compressor cycles on and off), and an 0.83 system derate factor for real-world losses (wiring, inverter, soiling, temperature).

Heat Pump Size	Daily kWh	Panels at 4 PSH	Panels at 5 PSH	Panels at 6 PSH
1-ton mini-split	2.3	2	2	1
1.5-ton mini-split	3.3	3	3	2
2-ton ducted	6.8	6	5	4
3-ton ducted	10.8	9	7	6
4-ton ducted	14.9	12	10	8
5-ton ducted	18.9	15	12	10
3-ton geothermal	5.8	5	4	3
5-ton geothermal	10.3	8	7	6

Formula: Daily kWh = (Running watts x hours x duty cycle) / 1000. Panels needed = Daily kWh / (panel watts x PSH x 0.83 / 1000).

These figures cover normal cooling and mild-weather heating. If you rely on the heat pump for winter heating in a cold climate with frequent aux heat use, multiply the panel count by 1.5 to 2.5 to cover those high-draw months.

Try The Calculator

Enter your heat pump's wattage and your location's peak sun hours to see exact production numbers.

Solar panel wattage

Type any value 10–750 W. Common sizes: 100 W (portable), 400 W (residential 2026), 580 W (commercial).

Peak sun hours per day

hrs

Don't know your PSH? Find your exact value →
Benchmarks: U.S. avg 4.98 · Phoenix 6.54 (highest) · Seattle 3.95 · Anchorage 3.17 (lowest). Above ~5.5 = sunny · 4.5–5.5 = average · below 4.5 = cloudy.

Daily kWh production

0.00kWh

Based on a 400W panel and 5.32 peak sun hours per day

Daily

1.60kWh

average across the year

Monthly

48kWh

× 30 days

Yearly

583kWh

× 365 days

Monthly production for a 400W panel — US Average

Jan

Feb

Mar

Apr

May

Jun

Jul

Aug

Sep

Oct

Nov

Dec

kWh per month · Source: NREL PVWatts v8

216 kg

CO₂ avoided per year

0.05

equivalent US homes powered

trees planted equivalent

$93

estimated annual savings

Tap to see sensitivity analysisSensitivity analysis

Sensitivity range
Scenario	Value
Low (-20%)	1.3 kWh
Expected	1.6 kWh
High (+20%)	1.9 kWh

Your daily production scales linearly with both panel wattage and peak sun hours. A 10% change in either input changes your result by 10%.

See production for your state Try the system size calculator

Which Heat Pump Type Is Best For Solar?

Mini-splits are the top choice for solar pairing. Their inverter-driven compressors ramp up gradually (no harsh startup surge), they use fewer watts per ton than any air-source option, and you can install them room-by-room to avoid conditioning empty spaces. A 1-ton mini-split running on just 2 solar panels is one of the most cost-effective heating and cooling setups available.

Geothermal systems are the efficiency kings -- using 30 to 60 percent less electricity than air-source units -- but the upfront cost ($15,000 to $30,000 for ground loop installation) offsets some of the solar savings. They make the most sense in extreme climates where air-source heat pumps would lean heavily on aux heat strips.

Standard ducted air-source systems are the most common and work well with solar, but plan for the auxiliary heat draw in cold climates. A 3-ton ducted system might need only 7 panels for cooling season, but 15 or more panels when aux heat runs frequently in January.

Tips For Reducing Heat Pump Wattage

Upgrade to a higher SEER2 unit. Going from 14 SEER2 to 20 SEER2 cuts electricity use by 30 percent.
Install a soft-start kit. A $100-$150 device reduces startup surge by 50 to 70 percent, which matters for generators and off-grid inverters.
Seal and insulate ductwork. Leaky ducts waste 20 to 30 percent of conditioned air, forcing the system to run longer.
Use a smart thermostat. Programming temperature setbacks during unoccupied hours reduces runtime by 10 to 15 percent.
Keep the outdoor unit clean. Dirty coils and restricted airflow increase wattage by 10 to 20 percent.
Right-size the unit. An oversized heat pump short-cycles (turns on and off frequently), wasting energy. An undersized unit runs constantly. Both increase total kWh consumed.