How Many Solar Panels Does It Take to Run a Heater?

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An electric heater is essential to keep you warm during those chilly winter days, and it makes living much more comfortable. Unfortunately heaters consume a lot of power, which is why many are switching to solar. The question is, how many solar panels does it take to run a heater?

It will take 5 x 300 watt solar panels to run a heater. Assuming each solar panel produces 300 watts an hour, five of these are enough to keep a heater running for 6 to 8 hours.

How Much Solar Power Does a Heater Need?

Heaters come in different sizes, but 1500 watts is the most common so we will use that as an example. For solar power ,we recommend the Renogy 300W Solar Panel Kit. Five of these should give you 1500 watts, enough to work with.

Heater power consumption x running time = solar panels needed

A Heater runs 2 to 3 cycles per hour. Each cycle can last 10 to 20 minutes so the heater will not use 1500 watts an hour. Assuming two 15 minute cycles per hour, that would be 750 watts an hour.

A 1500 watts solar system can run a heater for up to eight hours (or as long as there is enough sunlight), but this assumes two 15 minute cycles per hour. Some heaters run 3 cycles or two 20 minute cycles. In this case the system will consume 1500 watts an hour,.

While we use 1500 watt heaters as an example, you can try the same procedure for any heater size. A portable 150 watt heater will run on a Newpowa 12V Monocrystalline Solar Panel just fine. As long as the panel generates more than 150 watts an hour, the heater is going to work fine.

These runtimes are based on the assumption the solar panels produce 300 watts an hour. Output could fall below 300 watts under cloudy skies. Keep that in mind when you are calculating the runtime for a heater. Given that you will be using it during cold weather, it is better to be prepared for some drop in solar power production.

How Long Can Solar Panels Run a Heater?

Solar panels can run a heater as long as there is enough sunlight available. A 1500 watt heater will keep running as long as the solar panels can produce at least 1500 watts an hour.

When calculating solar appliance power requirements, always add 10%-20% more than what you expect to use. During summer you can expect solar power production to be close to its peak.

But during fall and winter – or the occasional summer storm – a solar panel will not be able to generate peak power. A 250 watt solar panel might produce only 235 or even 200 watts depending on the weather. keep this in mind not just for running a heater but any appliane on solar power.

Another factor to consider is the weather. All the calculations above assume it’s a clear sky with plenty of sunlight. Solar panel production will go down if it’s overcast. iI there’s a cloud overhead expect the output to drop a bit. It’s possible to get some solar power even during the winter, but don’t expect any during heavy rains.

All of this is by way of saying you should consider getting more solar power than what your heater requirements call for. A 10-20% cushion could mean the difference between being able to run your heater during winter and being left out in the cold, literally. This principle also holds true for all appliances you want to run on solar. Power wise, it is not that different from the solar power requirements of a 1.5 AC unit.

How Many Heaters Can a Solar Panel Run?

You can run as many heaters as you want on solar as long as there is sufficient power available. If you have a large solar array or a solar generator, you can operate as many heaters as you want. The important thing to remember is that a heater needs a consistent source of energy.

If you have a 1500W heater and want to another, how many solar panels will you need? It depends on how often you will use the heater. If you have two 1500 watt heaters, that is 3000 watts an hour. You will need 10 x 300 watts at the minimum. If you expect cloudy skies and limited sunlight, make that 12 x 300 watt solar panels..

That’s a lot of solar panels, which is why many solar power owners prefer to combine panels with solar generators or batteries. You could run the heater on solar panel and while it’s charging, plug it into the battery. This is why you should always have batteries to go along with your solar system. This should be the case whether you are using a heater or any other appliances.

Are Batteries Required to Run Solar Powered Heaters?

You need batteries to store solar energy, otherwise you will not be able to use a heater at night. Solar panels cannot run at night obviously, so you need a battery bank or AC power to keep the system running.

There are many types of solar batteries, and we have done a comprehensive comparison before. Lithium battery offers the best performance but is the most expensive. A good alternative is AGM as it also offers good results but does not cost as much.

If your 1500W heater runs for six hours a day, that’s 9000 watts. In other words you must have 2 x 400ah batteries to run a 1500W heater. You can combine two 200ah AGM Renogy Batteries or you can get just one battery and run the heater from a solar array half the time.

Any battery combination will do as long as the total is 950W-1000W+. The battery capacity needs to be a little over 9000W to be on the safe side.

AGM batteries have a 50% to 70% discharge rate, so when capacity drops to that level it has to be recharged. This is where having solar panels is handy as you can alternate the two as necessary.

Just like with solar panels, the battery capacity required will depend on how long you use the heater. In our example it is six hours. if you’ll be using it for loner periods, the battery capacity will be larger. If you’ll be using the heater less, then you’ll need a smaller battery.

You can use the same formula if you want to use a solar generator. Solar power station capacity is measured in watts so no need to do any conversion. There are even solar power stations that let you connect batteries together for greater power.

Should I Use Solar Powered Heaters?

Also known as solar air heaters, these devices have the same function as regular heaters – warming up space – but they work differently. Instead of using electricity to produce heat, it relies on solar collectors. Solar heaters have to be installed on windows or the roof to collect energy, similar to solar panels.

Solar heaters operate on a simple but effective mechanism. A built-in fan draws cold air from the room and is met by the collector’s thermal heat. The cold air turns warm and is released throughout the surrounding area. Like solar panels, solar air heaters will cut down your power cost. They are also durable, with warranties good for up to 10-20 years most of the time. if you want to buy, do some research first and go with a reputable manufacturer.

However, solar air heaters are not yet widely available. They are difficult to install and requires professional technicians. They are heavy and many states require a license to install one. However this was the case with solar panels just a few years ago, and look at solar energy today. It shouldn’t be too long before we see solar air heaters become commonplace at homes too. Fro now though, you can use solar panels to run regular heaters and save on costs.


Running a heater on solar panels is not only possible but practical. If you are going to use solar power, it’s a good idea to start slow, with the small appliances. Once you’re comfortable you can get a bigger solar power system and include your heater. Then you’ll notice that the heater will run as well as before, but you won’t be paying any monthly bills.