What Can a 25-watt Solar Panel Run? (Everything to Know)

In this blog post, I'll explain how much power does a 25w solar panel produce and what you can power with it.

What will a 25 watt solar panel run?

25w solar panel will produce about 100 - 120 watts of DC power per day, with this much power you can charge a cellphone, laptop, LED bulb, and small portable fan for a few hours.

keep reading... Now I'll explain how you can calculate the power output of your solar panel and also what size battery, charge controller, and inverter you need for 25-watt solar panel.

How Much Power Does a 25 watt Solar Panel Produce?

a 25 watt solar panel will produce about 100 - 120 watt-hours of DC power output per day.

Solar panels are designed and tested to produce their rated power under standard test conditions.

ideal conditions include:

  • 1000 watts per meter square of sunlight intensity (1kw/m2)
  • No wind
  • 25oC temperature

So in the real world, we take peak sun hours as a baseline when estimating the solar output.

  • 1 peak sun hour = 1k/meter2 of sunlight intensity

So to calculate how many total number of peak sun hours your location receives use this PV watt calculator

How many peak sun hours in florida?

Enter your complete address or just a city name, click "Go" and then select "Results".

Now you'd be able to see how many peak sun hours your location receives (as shown in the above pic)

To calculate the estimated real-world power output from your solar panels use this formula

Estimated Solar system output = (Solar system wattage * peak sun hours) * 0.8 

why multiply by 0.8? to cover the system losses, which will occur due to changes in weather conditions, tilt angle efficiency, due to charge controller, losses due to cables, etc...

How Much Power Does a 25 watt Solar Panel Produce?

What size battery for a 25w solar panel?

For a 25 watt solar panel, you'd need a 12v 30Ah lead-acid or 12v 20Ah lithium-ion battery.

To calculate the size of a battery, multiply the highest number of peak sun hours your location receives (by month, In my case its 6.9 in April) by the solar panel rated wattage and then divide the value by 12 for 12v battery

Required battery size = Highest peak sun hours * Solar panel rated wattage / 12

6.95 * 25 = 174 / 12 = 14.4 amp-hours 

Multiply the result by 2 for lead-acid type batteries (because of their 50% depth of discharge limit). and multiply it by 1.2 for lithium-ion type batteries

What size charge controller for 25w solar panel?

The charge controller is what regulates the power from the solar panel into the batteries.

the voltage and amps fluctuate during the day due to different sunlight conditions, if you'll connect your solar panel directly to the batteries it can affect the batteries.

so a charge controller will provide a 12v constant power to the batteries which will keep the batteries safe.

to calculate the charge controller size use this formula watts/volts = Amps + 25%

25/12 = 2.0 + 25% = 2.6A make it round about "5"

For a 25 watt solar panel, you'd need a 5A charge controller

What size inverter for 25w solar panels?

the inverter is used to convert the DC current into AC current to run our AC appliances, but we don't produce that much power from the 25w solar panels so that we can run large appliances like fridges, toasters, or TV.

But you wanna run a small appliance so you'll need an inverter or if you're using multiple 25w solar panels your total output will be higher.

so a 50w pure sine wave inverter is recommended for 25w solar panels, keep in mind that the inverter will cause a 15% of loss in current when converting DC into AC. FOVAL 150W Power Inverter will be the best option for you

so you'll receive 102wh of AC power from 25w solar panels

But if you have a 25w solar panel most probably you'll use it to charge your cellphone, laptop, or maybe a few other small appliances. so i recommend a jackery explorer 240 portable solar generator which will make your life easier.

you'll don't have to worry about the charge controller, inverter, and batteries, they are easy to set up and easy to carry on. Best for 25w solar panels which you can use while traveling or hiking.

I'm personally using a jacket 1000 portable power station for my RV trips and I'm quite satisfied with it click here to read my full review


25w solar panels can produce a small amount of power (about 120wh per day) which will help you to recharge your cellphones, and laptop and run a few led bulbs.

I hope you've gained some knowledge from this post, have a great day!

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Chris Tsitouris is a renewable energy professional with 10+ years of experience as Director of Engineering at Solar Spectrum, previously working as Project Manager at SunPower and Energy Analyst at the National Renewable Energy Laboratory. As a thought leader, Chris has authored numerous articles and research papers.

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