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Dehumidifiers have a reputation for being power hogs, but more energy efficient models are now available. If you want to run a dehumidifier with solar power, you must have the right hardware and specs.
A 300 watt solar panel and 200ah battery can run a dehumidifier for 12 hours a day. The average 30 pint dehumidifier uses 300 watts, but larger models consume up to 700, which require more solar power.
How to Calculate Dehumidifier Solar Power Needs
Dehumidifiers come in different sizes and types, but calculating power consumption is the same. We will look at common dehumidifier sizes later, but now let us go over the calculations.
Dehumidifier watts per hour x running time = solar panel and battery power required
Common residential dehumidifiers consume 280 to 300 watts an hour. A 300W Renogy solar panel kit can keep the dehumidifier going for 5 to 6 hours if there is enough sunlight available.
But most dehumidifiers need to run for 12 hours to be effective. At most you will get 5 to 8 hours of sunlight a day so it is not enough.
To keep the dehumidifier going you must have a battery bank to take over the solar panels. A 100ah battery is 1200 watts if fully discharged. Even if you do a 50% DOD there would still be 600 watts left.
A dehumidifier needs to run for 12 hours. If it consumes 300 watts an hour that is 3600 watts. A 300W solar panel can provide 1500 watts and a 200ah 12V battery will supply 2400 watts, enough to power the dehumidifier for the needed time.
To summarize, multiply the dehumidifier watt usage by its runtime. The result is the minimum solar power required. Because solar panels cannot run at night, you have to supplement the power with a battery.
Which Dehumidifier Size Works with Solar Panels?
The right solar panel size depends on how much you use the dehumidifier and its capacity. There is no one size fits all here.
A 350W solar panel can run 20-30 pint dehumidifiers for at least 5 hours in clear weather. A large dehumidifier requires more solar power to run. This table illustrates the most common dehumidifiers and their power requirements.
Solar Panel Size For Dehumidifier
Majority of home dehumidifiers are in the 20 to 50 pint size, so power consumption ranges from 280 to 600 watts. If the dehumidifier is too large it will consume a lot of solar power. If it is too small it won’t be able to provide enough humidity.
|Dehumidifier Size (In Pints)||Solar Panel Watts Needed||Amps (24V Battery)|
From the table above you can determine what solar panel size is suitable for your dehumidifier. Keep in mind these are the minimum solar panel outputs, and opting for a larger size is a good idea. Refer to your dehumidifier documentation for details on power consumption.
How Long Will My Solar Panels Run a Dehumidifier?
Just like with any other appliance running on solar power , the runtime depends on the weather, the solar panel and the sun.
Let us take a typical dehumidifier, running for 12 hours at 280 watts an hour. The total power consumption is 3360 watts.
A 300 watt solar panel can yield 1500 watts with five hours of sunlight. But on some days you might get 4, 6, 7 or 8 hours, If you regularly get 7 hours of sun, production can reach 2100 watts. But it there are only four hours, output can go down to 1200 watts.
This has a direct effect on the required battery size. In our calculations, a 280W dehumidifier can run for 12 hours with a 300W solar panel and a 200ah battery.
This assumes the dehumidifier runs on the solar panel for five hours and on the battery for the remaining seven. But if there are longer sun hours available, you can get away with a smaller battery. If sunlight is limited you need more battery power.
If your location receives 8 hours of sun, a solar panel can generate 2400 watts. A 100ah 12V battery can supply the rest of the power needed by the dehumidifier.
Solar Panel Output Variability
Even if there are 8 hours of sunlight, that does not guarantee the panels generate maximum power. Ideal weather makes it more likely, but many factors affect solar power production.
Under perfect weather conditions, a 350 watt solar panel can reach 350 watts. But for how long? Ideally it should be for as long as the sun is out. But that is not how solar power works.
Solar panel watt ratings are based on maximum output conducted in laboratory and controlled conditions. So if a solar panel is rated 250 watts, that is its maximum output.
A 300 watt solar panel can, in theory, convert up to 300 watts an hour. In fact that is likely during peak sunlight. But as the sun changes its position in the sky, the panel energy conversion rates drop.
There are ways to maximize solar panel output for your dehumidifier:
- Install the panel facing true south.
- Ensure there are no debris on the solar cells.
- There are no leaves or debris obstructing the solar panel.
- The panel is properly connected.
- Use the panel in clear, sunny weather.
Under these conditions you should get very good production from the solar panel. During summer, expect solid production, enough to run a dehumidifier for several hours.
How Many Batteries Do I Need to Run a Dehumidifier?
Solar panels are great, but without the sun there is no power. This is where you need batteries to come in.
There are two ways to use a dehumidifier.
- Run it with solar panels. When the sun goes down, the system switches to batteries.
- Run the dehumidifier with batteries. Use the solar panels to recharge the battery.
In the second scenario, the solar panels will not directly power the dehumidifier. It will run continuously on the batteries.
- In scenario 1, a 300W solar panel and a 200ah battery can run a 20 pint dehumidifier for 12 hours.
- In scenario 2, you need a 12V 300ah or 24V 150ah battery. This is enough to keep the dehumidifier running for 12 hours. The Ampere Time 300ah 12V LiFePO4 battery is a perfect fit.
When the battery runs out in scenario 2, you can recharge it with AC power or a 3600 watt solar array . You need 3 x 300W solar panels to recharge a 300ah battery in 4 to 5 hours.
Running a dehumidifier on batteries is better than on solar panels. One, you are not dependent on the sun. Two, you don’t have to worry about cloudy skies or rain affect power. Three, you don’t need to do any system switching.
Fourth, most dehumidifiers work best when running from 10:00 PM to 7:00 AM. There is no solar power available, so you really have to depend on the batteries.
Battery Depth of Discharge and Usage Explained
If you do decide to run a dehumidifier with batteries, there are two things to keep in mind. The depth of discharge and how long you will use the dehumidifier.
Suppose you have a dehumidifier and want to run it 12 hours every day. How many batteries will you need? And how many solar panels are needed to recharge them?
You need a 1200ah battery bank to run a dehumidifier for 12 hours a day every day. You also need 4 x 300W solar panels to recharge the batteries in one day.
A 300 watt dehumidifier running for 12 hours needs a 12V 300ah battery. When the battery runs out, use a 3600 watt solar array to recharge.
To keep the dehumidifier going however, you need another 300ah battery. When one runs out you can use the other. But this will fully discharge the batteries, a no-no if it is lead acid. If you want to recharge at 50%, you have to double the capacity to 600ah.
These numbers presume you will only use the batteries and solar panels for the dehumidifier. A much larger solar power system is needed if you will run other appliances.
Running a dehumidifier on solar is not as cost prohibitive as it used to be. If you want to give this a try, decide on the dehumidifier size and if your solar panels and batteries are large enough.