An electric furnace is a heating system that heats a home with electricity and often uses a fan to drive air through the ductwork. Electricity is often more expensive to heat a home than natural gas or other kinds of fuel. The cost of operating an electric furnace varies greatly based on the size of the house, the type of electric furnace utilized, the cost of energy, and the climate. To reduce this cost, you might wonder how many solar panels will it take to run an electric furnace?
As a general rule, the solar panel wattage needed will have to match the wattage of the electric furnace. For a 1500-watt electric furnace, you will need at least 1500 watts of solar panels or 5 x 300-watt solar panels. To effectively run the electric furnace during wintertime, you will have to double that to 10 x 300-watt solar panels.
How much electricity does an electric furnace use?
A 1500-watt electric furnace will use 1500 watts or 1.5 kW of electricity per hour that it is on. If you keep the furnace on for 10 hours per day, it uses 15kw of electricity per day.
If you are billed at $0.15 /Kw for electricity, then the electric furnace will cost you $0.15 x 15 = $2.25 per day to run. Multiply this by 30 days to get your monthly cost of $67.50 to use the electric furnace.
Using solar panels, you can eliminate this cost and even generate some additional power that can be used to power other appliances.
How many solar panels will I need?
If the electric furnace uses 1.5 kW of power per hour, you will have to use enough solar panels to provide at least as much power.5 x 300-watt solar panels will give you 1500-watts, and 4×400-watt will give you 1600-watts.
This will work well in summer when you have plenty of sunshine, but electric furnaces are used in winter to produce heat. Then we do not have as much sunshine and the sunshine that there is lesser intensity.
You will also have days of autonomy ( days without sunshine) where the solar panels will have no output, and you will have to rely solely on battery power for the electric furnace.
On days where sunshine, 5 x 300-watt solar panels will produce less than half their rated output on average in wintertime. This gives you 500 to 700 watts, which will not be sufficient to power the electric furnace.
You will thus need double the amount of solar panels you think – to run a 1.5kw electric furnace.
You will need 10 x 300-watt solar panels. This will provide you with the capacity you will need. By using extra panels in summer, you will have some extra power that can be used to power other appliances as well.
In wintertime, you will just about manage by using the 10 x solar panels.
Will I need batteries for my electric furnace?
If you want to use the power generated by your solar panels at night to power your electric furnace, then you will need batteries to provide that power.
In our example, the electric furnace uses 1.5kw per hour of electricity. If you look at using 24v batteries, that is 62.5 AH used by the furnace per hour.
Running the furnace for 10 hours through the night will use 625 AH of battery power.
In terms of batteries to run your electric furnace, you will have 2 options:
- Lead-acid-batteries have a depth of discharge (Dod) rate of 50% which should not be exceeded if you do not want to damage the battery and prolong it working life. If you are using lead-acid then you will have to double the 625AH to 1250AH of battery capacity.
- 12 x 200AH lead-acid batteries will be sufficient to power the electric furnace.
- Lithium-ion batteries have a depth of discharge rate of 80% or more , thus you are looking at 1.5kw of battery storage. Lithium-ion batteries are also not rated in AH, but in KW.
- a 1.5KW lithion-ion battery pack will be sufficient to power your electric furnace for 10 hours.
Can Solar panels power electric heating?
Solar panels can be used to power electric heating, but it has to be paired with a battery bank that can store the solar panels’ power for use during the night when the sun is not shining. The solar panels and battery capacity need to be sufficient to power the solar electric furnace.
Electric heating is an energy-intensive process, and it uses the most electricity in most, if not all, households. By looking at solar panels to provide some if not all of the electricity used by electric heating, you can reduce your utility bill by a significant amount.
Should I get an electric furnace if I have solar panels?
If your solar panels have enough capacity and produce sufficient power, then you can get an electric furnace. It would help if you remembered that you would probably want to use the electric furnace during the night when it is coldest, and then you will have to get a battery bank together with the solar panels to run the electric furnace.
Setting up a solar system with a battery bank can have a high upfront cost of $10,000 or more. Adding batteries to the solar panels is the most expensive part of a solar system. Not adding an energy-intensive process like heating can drastically reduce the number of batteries that you will need.
Heating is a very energy-intensive operation. There are some other options available such as natural gas (if available), which can be very cost-effective and worth your consideration.
