How much power does a 100W solar panel produce per day?
A 100W solar panel produces about 387 Wh a day at 4.5 peak sun hours after typical 14% losses — about 30 Ah into a 12.8 V battery, or 11.6 kWh a month.
How to work it out
- 100 W × (1 − 14% losses) = 86 Wh per peak sun hour
- × 4.5 peak sun hours = 387 Wh a day (30 Ah at 12.8 V)
One 100 W panel is the classic starter for a van, boat or camper. Its daily output depends far more on where and when you use it than on the brand: from under 140 Wh in a Seattle December to over 550 Wh on an average Phoenix day.
Adjust for your project
More options: Losses · Battery V
- Per month (30 days)
- 11.6 kWh
- Per year
- 141 kWh
- Into a battery per day
- 30 Ah
- In one hour of full sun
- 86 Wh
- Peak charging current (MPPT)
- 7.8 A
Output at other peak sun hours
| Peak sun hours per day | Output per day | Per month (30 days) | Into a battery per day |
|---|---|---|---|
| 2 | 172 Wh | 5.2 kWh | 13 Ah |
| 3 | 258 Wh | 7.7 kWh | 20 Ah |
| 4 | 344 Wh | 10.3 kWh | 27 Ah |
| 5 | 430 Wh | 12.9 kWh | 34 Ah |
| 6 | 516 Wh | 15.5 kWh | 40 Ah |
| 7 | 602 Wh | 18.1 kWh | 47 Ah |
What a 100 W panel will and won’t run
- It keeps up with small things. About 387 Wh a day covers phones, LED lights, a fan and a laptop for a few hours.
- It doesn’t keep up with a fridge on its own. A 12 V compressor fridge averaging 25 W uses 600 Wh a day — about one and a half panels’ worth on a good day.
- Per hour, at best ~86 Wh. In an hour of full sun, after losses, it makes about 86 Wh; at dawn and dusk, a small fraction of that.
- Current into the battery. Through an MPPT controller, up to about 7.8 A at 12.8 V in full sun; Victron’s own worked example is 7.7 A at 13 V.
For a bigger panel, see how much power a 200W solar panel produces per day. How long this panel takes to refill a battery is on how long a 100W solar panel takes to charge a 100Ah battery, and how many panels a 100 Ah battery needs is on how many solar panels to charge a 100Ah battery.
Different size? Use the full Solar Panel Output Calculator.
What you’ll need
- 100 W solar panelMid-range price
The building block of most van, boat and RV systems. Check the data-sheet Voc and Isc before you decide how to wire several of them.
See options on Amazon (opens in a new tab) - 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) - PWM solar charge controllerBudget price
Simple and cheap for one or two 12 V panels on a 12 V battery. It ties the panel to battery voltage, so it harvests less than MPPT in cool weather.
See options on Amazon (opens in a new tab)
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Frequently asked questions
How much power does a 100W solar panel produce in Phoenix?
About 565 Wh a day at Phoenix’s yearly average of 6.57 peak sun hours (PVWatts, tilted panel).
How much power does a 100W solar panel produce in winter in Seattle?
About 137 Wh a day at 1.59 peak sun hours, Seattle’s lowest month on PVWatts.
How many amp-hours does a 100W solar panel produce per day?
About 30 Ah into a 12.8 V battery at 4.5 peak sun hours.
Other common sizes
- How much power a 200W solar panel produces per day — 774 Wh a day at 4.5 sun hours
- How much power a 400W solar panel produces per day — 1.55 kWh a day at 4.5 sun hours
Sources
- National Laboratory of the Rockies (formerly NREL) — PVWatts® Calculator (opens in a new tab) — Look up the solar resource (peak sun hours) and yearly output for your own address; default system losses 14%.
- NLR (formerly NREL) — PVWatts® v8 API, NSRDB PSM V3 TMY data (opens in a new tab) — City figures on this site: fixed open-rack array facing due south, tilted at the site’s latitude, 14% system losses, queried October 2026.
- 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.