Determining Solar Power needed to Run a Space heater

A space heater can be a great alternative to a traditional floor or wall-mounted heating system. space heaters are also small and portable and don’t require ductwork. space heaters are also energy efficient and won’t require as much power to run. 

A typical space heater will use between 1000 and 3000 watts, depending on the model. A low-wattage unit will be fine if you’re just looking to warm up a small area. Compared to other home appliances like your microwave the power consumption is higher.

A high-wattage unit will produce more heat but might take longer to do so because it takes more energy to get from room temperature up to 70°F or whatever temperature setting you’ve set. 

Determining Solar Power needed to Run a Space heater

Solar Power for a 1500-Watt space heater

You will need 10 watts of heating power for every square foot of floor area in a room. A 1500 Watt heater is a good option to run off-grid. So how many solar panels and batteries are required to run a 1500 Watt heater and keep warm during those chilly days?

The amount of solar power to run a 1500-watt space heater will depend on how long you are running the heater.  So how much solar power will you need?

To run a space heater for an hour you’ll need a 600-Watt solar panel or three 200-watt solar panels with a 24v 300Ah LiFePO4 battery. You’ll also need an inverter that’s at least 2000 Watts for the space heater. 

We take you through the numbers and show you how you can use a smaller system to run the same heater for shorter periods of time throughout the day.  An important metric that we use to determine is the Watt-hour. 

Space heater Watt-hour Requirement

Electrical energy is measured in watt-hours. One watt-hour equals one watt expended for one hour. The number of watt-hours used by an appliance over a period of time equals the total amount of power consumed by that device over that period. 

To calculate watt-hours, multiply the watts used by an appliance over a period of time by the number of hours that appliance is used. If you use a 1500 Watt space heater for 1 hour, it will consume about 1500 watt-hours or 1.5 kWh. 

How Many Solar Panels to power a space heater?

In order to determine how many solar panels are needed for a hair dryer, we divide the total watt-hours required by the number of sun-hours we get in a day. So in our case, we need 1500Wh. 

An example is to use an average of 4 hours which could be high peak hours in the afternoon between 12 and 4. If you get more than 4 hours of sun per day, then use that number.

It’s important to note that the amount of solar energy that can be captured and used by a solar panel system is not just dependent on the amount of sunlight that is available, but also on other factors such as the panel’s efficiency, the angle at which the panels are tilted, and the presence of any shading or obstructions.

1500Wh/4= 375 Watts

A 375 Watt solar panel or two 200-watt solar panels will be enough to provide 1500Wh in the course of the day. Solar panels are not that expensive so you can even go double up to 750 Watts or three 200-watts solar panels and collect more power. 

What Size Battery do you need for the space heater?

To find the size of the battery, you divide the watt-hours by the voltage.

In the case, you have a 12-volt system, so you divide 1500Wh by 12V and for a 24V system, you divide by 24V. 

1500/12 = 125 Ah

1500/24 = 62.5 Ah

This however does not give you the size of the battery you need but the capacity of the battery reserve that the space heater is pulling through your inverter.  So you need a battery that you can safely pull 125 amps per for the 12v system and 62.5 amps per hour for the 24v system.

100 amps is a lot to pull from any system and will require bigger wires and a bigger battery so it is best to go with a 24v system pulling 63 amps. 

To pull just over 63 amps per hour you’ll need a 24-volt 300Ah LiFePO4 battery bank

Inverter for your space heater

All of this will be running through an inverter so you need to ensure you have an inverter that can power 1500 watts. This will require at least a 2000-Watt inverter. 

How Much Solar Power will you need for a space heater for 15 minutes?

Rather than using a space heater over the course of a full hour, you can opt to heat your room over intervals of a few minutes. Some space heaters come with this feature already pre-installed and will warm up a room at different settings over a period of time. 

So how much power would you need for 15 to 30 minutes of use? 

Since we already have a figure when using the space heater for an hour for 30 minutes we can half the power use and for 15 minutes we half it again. 

Length in timeWatt-hour RequirementsSolar PanelBattery
1 hr1500Wh600 Watts300Ah
30 minutes750Wh300 Watts150Ah
15 minutes375Wh150 Watts100Ah

Conclusion

Heating a home requires a lot of power however a space heater can save you on the amount of power required to warm up a room. Running at intervals of 15 minutes per hour can lead you to use less power from your solar system and ensure a constant flow of heat. If you trying to save on the power you are using from a space heater ensure the room is properly insulated and the windows are closed to prevent any heat from escaping. 

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