Quick answer: start with 1,300 W of solar
A pellet stove makes its heat from pellets but stops when the power does: no blowers, no auger, no fire. Keeping one running for 12 hours takes about 2,880 Wh a day, roughly 1,300 W of solar, and an inverter that can carry the igniter for several minutes rather than just a momentary surge.
Planning result
At 200 W per module, the array target is 7 panels. That count assumes four peak-sun-hours, 75% end-to-end solar yield, 90% conversion efficiency, and a 20% planning margin. This is a winter-only load, so it lands in the weeks with the fewest sun-hours, and it is the load you most want running during a storm outage.
How a pellet stove actually uses power
Planning case: a freestanding pellet stove or insert that burns wood pellets but needs electricity for its igniter, combustion blower, room-air blower, auger motor, and controls. Manufacturer ratings run about 4 A at 120 V during the start cycle and about 1 to 3 A once lit (Quadra-Fire Classic Bay 1200: 4.1 A start, 1.1 A run; Harman P-Series: 4.2 A start, 2.8 A run). The 600 W planning figure covers the start cycle with margin, and the 40% duty factor turns it into an average of about 240 W over 12 heating hours.
The electric load has two phases. During ignition a resistance igniter glows for several minutes while the blowers start, so the draw is several hundred watts. Once the fire is established, the auger feeds pellets in short pulses and the blowers run steadily at a speed set by the heat output, so the draw drops to roughly that of a large light bulb. A stove that relights several times a day repeats the high-draw phase each time.
Load calculation from running watts and duty cycle
The appliance-class estimate is 600 W running for 12 h/day at a 40% duty cycle, an average of about 240 W across those hours:
Then losses and reserve raise the energy the system must collect to about 3,840 Wh/day.
Typical manufacturer nameplate/manual range for the pellet stove class, triangulated with Harman (Hearth & Home Technologies): P-Series pellet stove owner's manual and Quadra-Fire (Hearth & Home Technologies): Classic Bay 1200 pellet insert owner's manual, then reduced to a conservative planning midpoint; this is not a product specification. Verify the exact unit's nameplate and manual before sizing.
Use a plug-in energy meter through a full cold day that includes at least one cold start, and read the daily watt-hours. The watts on the label usually describe steady running, not ignition.
Solar and battery sizing table
| Design item | Planning value | Basis |
|---|---|---|
| Appliance energy | 2,880 Wh/day | Running W × hours × duty cycle |
| Solar collection target | 1,300 W | 4 peak-sun-hours, 75% yield, 20% margin |
| 200 W panel count | 7 | Rounded up; real modules must satisfy controller voltage/current limits |
| One-day battery allowance | 4,800 Wh | 90% conversion efficiency, 80% LiFePO4 usable fraction, 20% margin |
| 12.8 V LiFePO4 equivalent | 375 Ah | Nominal planning conversion |
| 25.6 V LiFePO4 equivalent | 190 Ah | Nominal planning conversion |
Because the stove runs overnight and through storms, size the battery for at least one full heating day and plan how it will recharge during a cloudy stretch.
Build the closest passing wiring-diagram preset
The Pellet Stove Planning System preset is an engine-passing starting point whose array, battery bank, continuous inverter rating, and surge rating each meet or exceed this page's stated planning allowances. Adjust it only from measured load data and verified equipment limits.
Inverter and startup current
Use at least 800 W continuous with 800 W surge for this planning case. The igniter is not a surge in the inverter sense: it draws its few hundred watts for minutes, longer than most inverter surge ratings last. That is why this page sets the continuous inverter allowance from the start cycle, 800 W, which meets the minimum of 800 W of inverter capacity that Quadra-Fire's manual asks for during the start cycle.
Because this load draws its full power for long stretches rather than for a moment, the battery-to-inverter cable carries heavy current continuously. A run that is too long or too small wastes energy as heat and can push the inverter to its low-voltage cutoff late in the day, even with energy left in the battery, so use the diagram machine's real run length and keep every fuse within the equipment and conductor limits. The 700 W peak estimate is a planning figure, not the manual's rating.
The common mistake
Ways to cut the load
- Let the stove modulate down instead of switching it off and on; each relight repeats the igniter's high-draw minutes.
- Clean the burn pot and ash traps on schedule so ignition succeeds the first time.
- Use the stove's thermostat or low-heat mode rather than manual on and off cycles.
- Check whether the manufacturer approves an inverter or a specific battery backup unit before you rely on one.
What to verify before buying equipment
- The exact running watts, startup current, voltage, frequency, and required circuit from the appliance label and manual.
- Actual watt-hours over a representative day; seasonal heating or cooling loads need a design-day measurement.
- Local peak-sun-hours for the worst operating season, plus shade and array orientation.
- Controller maximum input voltage at the coldest expected temperature and maximum output current.
- Battery discharge current, series/parallel permission, terminal torque, low-temperature controls, and overcurrent protection.
- Conductor ampacity, voltage drop, terminal temperature ratings, disconnecting means, grounding, local amendments, and inspection requirements.
For a whole-system load list, use the load and appliance calculator. For the system context around this appliance, continue to the Off-grid heating and cooling guide.
Frequently asked questions
How much solar do I need for a pellet stove?
For the planning case on this page (a pellet stove's igniter, blowers, and auger over a 12-hour heating day), allow about 1,300 watts of solar at four peak-sun-hours per day. That covers an estimated 2,880 Wh daily load plus conversion, temperature, and recharge margin. Heating season has the fewest sun-hours, so many owners add margin or a backup charging source.
What size inverter should I use for a pellet stove?
Plan on at least 800 W continuous and 800 W surge. Choose the continuous rating to cover the igniter plus the blowers for several minutes; a pure sine wave output is the safe choice for the stove's control board.
What battery size keeps a pellet stove running for one day?
The one-day planning allowance is about 4,800 Wh nominal usable design capacity, roughly 375 Ah at 12.8 V or 190 Ah at 25.6 V for LiFePO4. Plan more than one day if the stove is your heat source during outages.