Quick answer: start with 4,700 W of solar
A 2-ton system is a whole-house load for a small home. At about 2,200 W running 60% of 8 hours it needs about 10,560 Wh a day, roughly 4,700 W of solar and, for overnight use, a battery near 17,600 Wh. Off-grid homes that run one usually pair it with heavy insulation and a variable-speed outdoor unit.
Planning result
At 200 W per module, the array target is 24 panels. That count assumes four peak-sun-hours, 75% end-to-end solar yield, 90% conversion efficiency, and a 20% planning margin. The summer design day lines up with strong sun, but heat stored in the walls and roof keeps a central system running into the evening after production falls.
How a 2-ton air conditioner actually uses power
Planning case: a 2-ton (24,000 BTU/h) central or ducted split air conditioner on a 240 V circuit, drawing about 2,200 W with the compressor and outdoor fan running at about 60% on-time across 8 hours. The indoor blower is extra unless your measurement already includes it. Goodman's 2-ton GSXN4 uses about 1.95 kW of total system power, blower included, at 95 °F outdoors.
A central system has three loads: the outdoor compressor, the outdoor condenser fan, and the indoor blower that pushes air through the ducts. The compressor dominates, and a single-stage unit runs it at full power in long cycles on hot afternoons. Leaky ducts in an attic or crawlspace add runtime without adding comfort.
Load calculation from running watts and duty cycle
The appliance-class estimate is 2,200 W running for 8 h/day at a 60% duty cycle, an average of about 1,320 W across those hours:
Then losses and reserve raise the energy the system must collect to about 14,080 Wh/day.
Typical manufacturer EnergyGuide/nameplate/manual range for the 2-ton air conditioner class, triangulated with Goodman: GSXN4 split system air conditioner specification sheet and U.S. Department of Energy FEMP: Purchasing energy-efficient residential central air conditioners, then reduced to a conservative planning midpoint; this is not a product specification. Verify the exact unit's EnergyGuide label, nameplate, and manual before sizing.
Use a whole-circuit energy monitor on the condenser and air-handler circuits, or read the utility meter on a hot day with other loads off. The nameplate's rated load amps show the running draw; daily kWh is what sizes the array.
Solar and battery sizing table
| Design item | Planning value | Basis |
|---|---|---|
| Appliance energy | 10,560 Wh/day | Running W × hours × duty cycle |
| Solar collection target | 4,700 W | 4 peak-sun-hours, 75% yield, 20% margin |
| 200 W panel count | 24 | Rounded up; real modules must satisfy controller voltage/current limits |
| One-day battery allowance | 17,600 Wh | 90% conversion efficiency, 80% LiFePO4 usable fraction, 20% margin |
| 12.8 V LiFePO4 equivalent | 1,375 Ah | Nominal planning conversion |
| 25.6 V LiFePO4 equivalent | 690 Ah | Nominal planning conversion |
Every hour the system runs after sunset comes from the battery. Shifting cooling into the solar window by pre-cooling and then coasting is cheaper than adding storage.
Build the closest passing wiring-diagram preset
The 2-Ton Air Conditioner 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 2,800 W continuous with 10,500 W surge for this planning case. A single-stage compressor draws its locked-rotor current for a fraction of a second at every start: Goodman lists 41.2 locked-rotor amps for its 2-ton compressor, about 9,500 W at 230 V, so the surge allowance here is 10,500 W. A soft starter rated for the compressor reduces that peak, and a variable-speed outdoor unit largely avoids it.
The 9,500 W startup estimate is not a substitute for the manual's locked-rotor, compressor-start, or motor-start requirements, and an inverter's surge rating usually lasts seconds, not minutes. A battery-to-inverter cable that is too long or too small can pull the DC input below the inverter's low-voltage threshold during that start even when the battery has plenty of energy, so use the diagram machine's real run length.
The common mistake
Ways to cut the load
- Seal and insulate the ducts, or move them inside the conditioned space.
- When the condenser is due for replacement, a variable-speed heat pump lowers both the start surge and the part-load energy.
- Raise the set point a few degrees and use ceiling fans so the system cycles less.
- Fit a soft starter rated for the compressor if the existing unit has to stay.
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 2-ton air conditioner?
For the planning case on this page (a 24,000 BTU/h central or split system cooling a small home for eight hours), allow about 4,700 watts of solar at four peak-sun-hours per day. That covers an estimated 10,560 Wh daily load plus conversion, temperature, and recharge margin. A well-insulated home with a variable-speed system can use considerably less than this planning case.
What size inverter should I use for a 2-ton air conditioner?
Plan on at least 2,800 W continuous and 10,500 W surge. The inverter must supply 240 V to the condenser and ride through its compressor start; confirm both against the equipment manuals.
What battery size keeps a 2-ton air conditioner running for one day?
The one-day planning allowance is about 17,600 Wh nominal usable design capacity, roughly 1,375 Ah at 12.8 V or 690 Ah at 25.6 V for LiFePO4. Overnight cooling dominates storage; shifting cooling into the afternoon shrinks it.