How Many Batteries Can a 60W Solar Panel Charge?

60W solar panels provide enough power to run a computer, a drone and other electronic devices. They can be used to charge batteries too, but how many and what size? Before you start charging, better be sure the panel can handle it.

A 60 watt solar panel can charge one 50ah battery in 10 hours. It can generate 3 to 5 amps an hour or 20-25 amps a day, depending on the weather and system efficiency.

How to Calculate 60 Watt Solar Panel Charge Capacity

The calculation is total watts per day / volts = battery amp hour capacity. The charge time depends on the weather, efficiency of the system and battery discharge level.

A high quality module like the Togo Power Foldable Solar Panel can produce up to 300 watts a day with 5 sun hours (60 x 5 = 300). Now you need to convert watts to battery amp hours.

Watts / volts = battery amp hours

A standard 60W solar panel is designed for 12V batteries, so let’s use that:

300W / 12V = 25

A 60W solar panel can charge a 25ah 12V battery in one day, assuming 5 hours of sun is available. This is the ideal scenario and does not account for system energy losses which can cause the panel to produce less than its rated output.

Cloudy skies combined with system energy loss could drop output to 3 amps an hour. So it might take the panel 6 to 7 hours to top off a 25ah battery. If you live in a sunny state it’s possible to get up to 7 hours of sun daily in the summer. But if you live in Maine or Wyoming, it might take a day or two to charge the battery.

The calculations given here are for 12V batteries. You can use a different voltage like 24V but check first if your solar panel supports it. Standard solar panels are 18V and they are compatible with 12V batteries. If you have a 24V battery, an 18V solar panel may not work with it, so check compatibility first.

What is the Largest Battery a 60 Watt Solar Panel Can Charge?

There is no limit to the number of batteries the panel can charge over several days. But the larger the battery capacity, the longer it will take the solar panel to charge it.

Take a good 35ah lithium batter like the Mighty Max 12V for instance. Assuming perfect conditions and 7 hours of sunlight, the solar panel can only produce 420W (60 x 7 = 420) or 20ah, not enough. But if you charge the battery over two days you can fill it up.

Let us assume the weather isn’t ideal and the panel produces only 50W an hour. With 5 sun hours that is 500W over two days. 500 watts is equal to 41.6 amp hours, enough for the 35ah battery.

In theory you can charge even larger batteries, but it is not practical. For 25ah up to 50ah batteries you can use a 60W solar panel. For anything larger you are better off with a 100W solar panel. But this only goes to show that you can do a lot with a 60W solar panel, the only limits being the time it takes to fully charge the battery.

Always Use a Charge Controller

Always use a charge controller when charging batteries with a solar panel. The controller keeps the current moving at high levels without overcharging the battery.

Make sure the controller is large enough for your battery and solar panel otherwise you will overload the system. For a 60W solar panel and 12V battery, a 15A to 20A charge controller is ideal. If you are going to use more panels or create a solar array, increase the size of your charge controller accordingly.

For small scale use, a PWM controller will be fine. There will be some energy loss, but it is not enough to seriously affect performance. If you are going to connect several 60W solar into an array however, use an MPPT charge controller.

Battery Charging Times and Discharge Rate

The battery depth of discharge (DOD) affects charge times directly. Lead acid batteries have a DOD of 50% and lithium batteries up to 85% or higher. In many cases your solar panel only has to supply 50% of the power to top the battery.

Let’s take a look at a 50ah 12V battery. As noted earlier 60W solar panel can yield up to 300W a day, and that is not enough to fill a 50ah battery.

But if you practice good maintenance and recharge lead acid batteries at 50%, there is still 25ah left, and the solar panel only needs to generate 25ah to top it. The same rule applies to powerful solar panels as long as they are lead acid. With a 100ah battery, your solar panel only needs to supply 50ah and so on.

Of course the disadvantage here is you only get to use half the capacity, whereas with lithium ion it is much higher. The tradeoff is the faster charge time though. But with 60W solar panels you are unlikely to use large batteries anyway so lead acid may be more practical.

What Can a 60 Watt Solar Panel Run?

You can run a computer on a 60W solar panel, or a small water pump, several LED light bulbs, a fan and of course charge batteries. Connect the panel to a battery and you can power even more devices day or night.

The number of solar appliances you can use depends on the panel output and power requirements. A laptop uses 35W to 60W an hour, so you can run it for 5 hours a day until the sun goes down. You can also use various LED bulbs or a fan, or any number of appliances as long as the total is under 60W an hour.

Because solar panels do not produce power consistently, there will be time when output drops below 60W. That is why it is better to run your appliances and devices off a battery. The power supply will be consistent and you can use it any time of the day or night, whether it is sunny, raining or snowy. As long as the battery is topped off and you know the discharge rate, you can keep running your devices.

While 60W solar panels have become more efficient, there are not as effective without batteries. You cannot run them at night and any extra energy will go to waste unless you store it in a battery. By using the solar panel to charge your battery, you can use your devices with confidence.

Keep in mind that your battery bank needs to be connected to an inverter to run AC appliances. You can load DC devices directly to a solar panel since the module produces DC power. Most home appliances are AC though, so an inverter is required.

Tips For Charging Batteries with 60 Watt Solar Panels

Sunlight Hours Available

Take into account the average number of sun hours in your area. Account for the season as well. Depending on your location and the season, 60W may be peak output or the average. Ideally you will always get 60 watts per hour, but realistically you will likely get 50 to 55 watts. Again, it depends on your location and the panel efficiency.

Discharge Rate

We already covered this so no need to repeat everything. But keep in mind that the DOD affects how fast or slow the charge will be. With a 50% DOD – and assuming you follow the recommended recharging rate – the panel only needs to generate half the stated capacity. So a 40ah AGM battery can be topped off with 20ah solar power if it is discharged at 50%.

Solar Panel Efficiency

Being out in front of the sun is not enough. A solar panel must be have an efficiency rating of at least 18% to charge batteries consistently. Batteries can be charged with electricity, but if you are using solar, make certain it is as efficient as possible.

Usage

What will you be using the solar panel for? Is it for a laptop? Are you going camping and need the panel to light some LED bulbs? Will you run a motor? Are you going to use DC or AC powered devices? Are you charging a battery for backup power or to use it for appliances?

You have to plan ahead to avoid frustration. Suppose you want to charge the battery and run a small solar TV on it. Check if the TV is DC or AC. If it is DC you can connect it directly to the battery. If it is AC, you have to connect an inverter to the battery and run the TV from the inverter.

You can run the TV or any DC powered device from the module, but since the power fluctuates, a battery is better. With a large enough battery you can keep running the appliance even at night.

Conclusion

If you know the capabilities of a 60W solar panel and have reasonable expectations, it can charge a portable battery and operate your devices too. It is not as powerful as larger solar panels, but it is portable and suited for camping.