Sizing a Solar and Battery System for a 1HP Aircon, Step by Step

To size solar for a 1HP aircon, work through five numbers in order: the aircon’s rated watts, its daily watt-hours, the battery needed for the hours without sun, the panel watts to refill it, and an inverter big enough for the aircon’s maximum draw. In our worked example, a 650 W TCL TAC-11CSD/P7 running 8 hours overnight needs about a 3.6 kWh battery and 800 W of panels to recharge it. A hybrid inverter such as the PowMr 4.5kW is a good fit for that system.

Every aircon figure below comes from a DOE energy label or the manufacturer’s spec sheet. Every assumption, such as hours of sun, is labelled so you can swap in your own.

The assumptions we use (change them to match your home)

Step 1: Find the aircon’s rated watts

Look at the yellow DOE energy label on the indoor unit. It shows the power input (W) and the CSPF (“Energy Efficiency Rating”). Here are the verified 1HP inverter units, lowest rated input first:

“1HP” isn’t a fixed size. The TCL P7’s label cooling capacity is 3,060 W and the TCL UB2’s is 2,600 W, so the lower-watt unit is also the one that cools more. Choosing a high-CSPF model is the cheapest way to shrink every number that follows. Our ranking of aircons for solar compares them all.

Don’t use a listing’s headline wattage. One Lazada listing for the TCL UB2 1HP says “1450 watts”, but that’s the top of its 200–1,450 W range. The DOE label says 850 W. Another listing for the Kolin 1HP gives “Rated Power: 1,200 W” next to the label’s 740 W. Use the label.

Step 2: Work out daily watt-hours

Daily Wh = rated watts × hours of use × average-load factor

Split day use and night use, because night use has to come from the battery.

For the 850 W TCL UB2, multiply by 850 ÷ 650 (about 1.31). Overnight at 50% becomes 3,400 Wh.

The 50% figure is a starting point, not a promise. A small, shaded, well-sealed bedroom set to 24°C (the DOE’s suggested setting) will run nearer the low end. A west-facing room with a tin roof on a hot afternoon may sit near full power for hours. If you can, measure your own aircon with a plug-in energy meter (window units) or check your bill before and after.

Step 3: Size the battery for the hours without sun

Battery Wh = night Wh ÷ inverter efficiency ÷ usable fraction

Overnight with the TCL P7 (example assumptions):

• Energy at the aircon: 2,600 Wh
• Energy out of the battery: 2,600 ÷ 0.9 ≈ 2,889 Wh
• Rated battery size: 2,889 ÷ 0.8 ≈ 3,611 Wh (about 3.6 kWh)

Add the idle draw of the inverter itself. PowMr lists under 35 W with no load for the 4.5kW model and under 50 W for the 6.5kW. Over an 8-hour night that’s up to 280 Wh or 400 Wh more.

Converting to amp-hours. Battery Ah = Wh ÷ battery voltage. LiFePO4 banks are commonly 25.6V for a “24V” system and 51.2V for a “48V” system:

• 3.6 kWh at 24V: 3,611 ÷ 25.6 ≈ 141 Ah
• 3.6 kWh at 48V: 3,611 ÷ 51.2 ≈ 71 Ah

A 12V system is a poor fit for aircons. 1,000 W from a 12.8V battery is about 78 A before losses, which needs very thick cables. Read LiFePO4 batteries for DIY solar before choosing cells.

Step 4: Size the panels

Panel W = daily Wh from solar ÷ (peak sun hours × real output fraction)

To refill the overnight battery (TCL P7, 8 hours at 50%): the battery delivered 2,889 Wh.

2,889 ÷ (4.5 × 0.8) ≈ 800 W of panels

To run the aircon in the daytime too (8 hours at 50%): 2,600 ÷ 0.9 ≈ 2,889 Wh through the inverter, so another ≈ 800 W.

Total for day and night use: about 1.6 kW of panels. For the 850 W TCL UB2, it’s about 2.1 kW.

Also check instant power. At noon the aircon may draw its full 650 W. Panels at 80% output need 650 ÷ 0.9 ÷ 0.8 ≈ 900 W rated just to carry that moment without the battery. A 1.6 kW array covers it with room to charge the battery at the same time.

Philippine weather matters here. A week of typhoon or habagat rain can cut solar output sharply for days. In those weeks you’ll need grid charging (hybrid inverters can do this), a bigger battery or fewer hours of cooling. Our rainy-season charging guide covers what to expect.

Step 5: Size the inverter for power and surge

The battery and panels cover energy. The inverter has to cover power: the highest draw at any moment.

1. Use the aircon’s maximum input, not its rated input. While pulling a hot room down to temperature, an inverter unit can draw up to the top of its range: 888 W for the Kolin KA-100GQAIINV32, 1,100 W for the TCL TAC-09CSD/FBI and 1,450 W for the TCL TAC-09CWI/UB2. The TCL P7’s maximum isn’t published, so allow at least as much as the FBI.
2. Add everything else on the same inverter: fans, ref, lights, router, TV.
3. Check surge. None of these aircons has a published starting current. The inverter units’ published input ranges begin low, at 148 W to 220 W, and the Kolin listing advertises “soft start-up”. A fixed-speed compressor starts at full power every cycle, and BLUETTI notes that motors and compressors can briefly draw 2 to 4 times their normal power. That’s one more reason to use an inverter aircon on solar.

Practical minimum for one 1HP inverter aircon alone: about 1,500 W continuous. Comfortable choices:

Worked example: putting it together

Goal: a 1HP bedroom aircon, 8 hours overnight plus 4 hours on weekend afternoons, with brownout backup.

1. Aircon: TCL TAC-11CSD/P7, 650 W.
2. Night energy: 650 × 8 × 0.5 = 2,600 Wh. Afternoon energy: 650 × 4 × 0.5 = 1,300 Wh.
3. Battery: 2,600 ÷ 0.9 ÷ 0.8 ≈ 3.6 kWh, plus inverter idle draw, so plan on about 4 kWh. At 24V that’s about 160 Ah.
4. Panels: night refill (2,889 Wh) plus afternoon use (1,300 ÷ 0.9 ≈ 1,444 Wh) = 4,333 Wh ÷ 3.6 ≈ 1.2 kW.
5. Inverter: PowMr 4.5kW hybrid, 24V battery.
6. String check: with PowMr’s 150W flexible panels (Voc 21.6V, Vmp 18V), 8 panels make 1,200 W. In series that’s 8 × 21.6 = 172.8V Voc, under our 405V limit (90% of the 450V maximum), and 8 × 18 = 144V Vmp, above the 55V MPPT minimum. If the system must start from solar with no battery, note that the listing gives a 150Voc start voltage. A licensed electrician should confirm the final string design against the panel nameplates.

The plug-and-play alternative

The same night load on a power station: the EcoFlow DELTA Pro 3 holds 4,096 Wh. 4,096 × 0.85 ÷ 325 W ≈ 10.7 hours at the example average draw, enough for one night. Its high-voltage solar input takes up to 1,600 W. One verified setup is six EcoFlow 220W panels in series (1,320 W, 129V Voc). EcoFlow’s manual specifies its Solar to XT60 cable for that port, and it doesn’t say whether the panels’ included cable fits. See powering an aircon with an EcoFlow power station.

Common sizing mistakes

• Using the listing’s “max watts” as the running load. It makes the battery look twice as big as it needs to be. Use the label’s rated input for energy and the maximum for the inverter.
• Forgetting the night. Panels sized for the day alone leave the battery empty by midnight.
• Sizing for perfect sun. Plan for a few grey days, or plan to charge from the grid.
• Ignoring idle draw. A hybrid inverter left on 24/7 can use up to 0.84 kWh (4.5kW) or 1.2 kWh (6.5kW) a day by itself.
• Picking a fixed-speed or “inverter grade” unit. Fujidenzo’s “Inverter Grade” WAR window units have fixed-speed CSPFs of 3.32 to 3.35. The TCL P7 is 7.11.

Check your own figures with the solar system size calculator and the power station runtime calculator.

Safety

A power station with portable panels can be set up by the owner following the manual. A hybrid inverter, battery bank and rooftop array wired into your home must be designed by or under a professional electrical engineer (PEE) and installed with an LGU electrical permit. Tell your electric company; Meralco offers a Zero Export arrangement for systems that won’t export. Net metering has its own process; see our net metering guide.

What to buy

Aircon (the most important choice):

• TCL TAC-11CSD/P7 1HP split, 650 W: Lazada · Shopee
• TCL TAC-09CSD/FBI 1HP split, 660 W: Lazada · Shopee
• Kolin KA-100GQAIINV32 1HP window, 740 W (max 888 W): Lazada

Hybrid system (licensed installer):

• PowMr 4.5kW hybrid inverter (24V) on Lazada
• PowMr 150W flexible solar panel on Lazada: check whether the listing variant is one panel or a pack, and use PowMr’s figures (Voc 21.6V, Isc 9.16A), not the listing’s
• A 24V LiFePO4 bank of about 4 kWh (see our LiFePO4 guide)

Plug-and-play:

• EcoFlow DELTA Pro 3: Lazada (EcoFlow PH) · Shopee
• EcoFlow 220W portable panels: Lazada

Check today’s price before you buy.

Bottom line

For one 1HP inverter aircon running 8 hours a night, plan on roughly a 4 kWh battery, 1 to 1.6 kW of panels depending on daytime use, and an inverter rated for at least 1,500 W continuous. Those are estimates; change the assumptions to fit your room and your habits. The biggest saving comes before you buy any solar: a 650 W, CSPF 7.11 unit like the TCL TAC-11CSD/P7 needs about a quarter less battery and panel than an 850 W unit.