What size charge controller for 1000 watts of solar?
On a 24 V battery, 1000 W of panels sends about 41.7 A through an MPPT controller — 52.1 A with 25% headroom, so a 60 A controller. On 12 V it would be about 83 A before headroom.
How to work it out
- MPPT: 1,000 W ÷ 24 V = 41.7 A
- × (1 + 25% headroom) = 52.1 A → 60 A controller
A kilowatt of panels is where 12 V systems start to strain. The current is high enough that many systems move the battery bank to 24 V or 48 V, or split the array across two controllers.
Adjust for your project
More options: Headroom
- Current with headroom
- 52.1 A
- Current with no headroom
- 41.7 A
- At other battery voltages (MPPT, with headroom)
- 12 V: 104 A · 48 V: 26 A
- Also check the controller’s maximum PV input voltage against your array’s cold open-circuit voltage — that is the limit that damages controllers. Use the series and parallel calculator.
Controller size for other array sizes
| Solar array watts | Current with no headroom | Current with headroom | Controller size to look for |
|---|---|---|---|
| 100 | 4.2 A | 5.2 A | 10 A |
| 200 | 8.3 A | 10.4 A | 15 A |
| 300 | 12.5 A | 15.6 A | 20 A |
| 400 | 16.7 A | 20.8 A | 30 A |
| 600 | 25 A | 31.3 A | 40 A |
| 800 | 33.3 A | 41.7 A | 50 A |
| 1000 | 41.7 A | 52.1 A | 60 A |
| 1200 | 50 A | 62.5 A | 70 A |
What to know about a controller for 1 kW
- 12 V: about 104 A with headroom. That is more than one common controller; you would split the array across two controllers of around 50–60 A each, each with its own panels.
- 24 V: one 60 A controller. About 52 A with headroom.
- 48 V: about 26 A. A 30 A controller; the battery cabling gets far easier too.
- Voltage limit. Residential-size panels have a much higher Voc than 12 V-class panels, so even two or three in series can approach a controller’s voltage limit on a cold morning — check with the series and parallel calculator using your panel’s data sheet.
For the whole system around this array, see how much solar for an RV or how many solar panels for a small cabin. Smaller arrays: what size charge controller for a 400 watt solar panel.
Different size? Use the full Charge Controller Size Calculator.
What you’ll need
- MPPT solar charge controllerMid-range price
Converts a higher panel voltage into charging current, so you can wire panels in series and lose less in the cables. Size it on output amps and maximum PV voltage.
See options on Amazon (opens in a new tab) - 400 W residential-size solar panelPremium price
Fewer, larger panels for a cabin, shed or ground mount. Their higher voltage usually means an MPPT controller.
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Frequently asked questions
What size charge controller for 1000 W on a 48 V battery?
About 26 A with headroom — a 30 A controller.
What size charge controller for 1200 W on 24 V?
About 62.5 A with headroom — a 70 A controller.
Other common sizes
- What size charge controller for a 400 watt solar panel — 50 A MPPT on 12 V (33.3 A minimum)
- What size charge controller for a 200 watt solar panel — 30 A MPPT on 12 V (a 20 A one would run flat out)
Sources
- Victron Energy — Which solar charge controller: PWM or MPPT? (2020) (opens in a new tab) — MPPT output current = panel watts ÷ battery voltage (100 W ÷ 13 V = 7.7 A); a PWM controller pulls the panel down to battery voltage (81 W from a 100 W panel at 25 °C, about the same as MPPT at 75 °C); temperature-coefficient method; example panel Voc 21.6 V, −0.35 %/°C.
- Victron Energy — Energy Unlimited (book) (opens in a new tab) — Lead-acid charge efficiency 80–95% (85% suggested as a starting value); battery energy efficiency about 75% for full cycles, about 89% in partial state of charge; inverter efficiencies above 90%.