How Many Solar Panels to Run a Hot Tub

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Nothing beats getting into a hot tub to unwind after a long day. For many people it is the best place to relax, but what if you live off grid? Does that mean you are stuck with cold showers? Not true, as solar panels can run a hot tub.

It takes 11 x 300W solar panels to run a 3000W hot tub with a 120V heater for 1 hour a day. If it is a 240V heater you need 22 x 300W solar panels, and both assume suitable conditions for solar panels to generate power.

How to Calculate Hot Tub Solar Panel Requirements

The conversion formula is hot tub + heater wattage x hours of use = solar panels needed.

Hot tubs use either a 120V or 240V heater. A typical hot tub uses about 1500W an hour, but add the heater and it increases to 3000W or 6000W. If you use a 3000W hot tub for 2 hours a day, 22 x 300W solar panels are required. As you can see the formula is really easy.

You don’t have to rely on the solar panels only. If your solar panel is large enough you can save extra energy in a solar battery and the reserve can be tapped for the hot tub later. You can also use a portable solar generator along with a solar panel for even more power.

Example: if you want to use solar panels only, 11 or 22 of them are required. We suggest the Renogy 300W for this purpose. You can also combine it with three 100ah Renogy batteries for use in the late afternoon or night.

How to Heat a Hot Tub to Solar Power

Important: consult a professional if you are not comfortable with unplugging the hot tub wires and other electrical components. Make sure to unplug everything and that the tub is completely drained of water.

Step 1 – Find a Location For Your Hot Tub

Make a note of how often you use your hot tub, its voltage (120V or 240V) and wattage. You can find the wattage details on the product manual or manufacturer website. Use this information to determine how many solar panels you will need.

Just like with a solar powered gate opener, a solar powered hot tub needs plenty of sunlight. Relocate the tub where it can receive the maximum amount of sun possible. When you find an ideal spot, place a cover on the tub, preferably translucent. This allows the hot tub to absorb the heat and reduce the amount of solar power needed.

Step 2 – Connect the Solar Heating Components

There are two options, buy a solar hot tub kit with solar heat exchangers, or use a solar panel system. Let us go over both methods.

Option 1 – Install a Solar Hot Tub Kit

If you bought a solar hot tub kit, follow the instructions on how to assemble the components. The light tube collectors should be mounted first, then the plumbing has to be assembled. Fill up the closed loop and it’s done. An integrated or drop in heat exchanger will be included depending on the kit.

Solar hot tubs kits will have varying components so the steps will differ. Just follow the guide or have an installer or handyman do it for you. Test the tub once everything has been installed.

Option 2 – Install Solar Panels on a Hot Tub

Once you know how many solar panels are required, it’s time to set up the system. If you have a 3000W hot tub, you need 11 x 300W solar panels, a charge controller, battery and inverter.

The battery is to store the solar energy absorbed by the solar panels, while the charge controller regulates the current flow. Lastly, the inverter converts DC power (produced by the solar panel) into AC so it can be used with your hot tub.

The battery and inverter must be the right size for your entire system. You are not going to use the solar power system for the hot tub only, so calculate how many watts your appliances use up to get the right specs for both battery and inverter.

Get all the solar components ready. Install the solar panels where it can receive maximum sunlight. Connect the charge controller to the battery, then connect it to the panels. Connect the charge controller to the inverter. Turn on the inverter and if everything is installed correctly, the solar panels will begin to charge.

Solar power manufacturers have different sequencing procedures, so in one system you connect the controller to the battery then the solar panel. In other systems you connect the solar panels to the battery then the controller. Refer to your product guide for specific steps.

Solar Hot Tub Installation Tips and Warnings

Installing solar panels or a solar heat exchanger kit is straightforward. But remember the following tips to get the best possible results from your hot tub.

Location, location, location. With solar panels this is paramount. If it’s mostly sunny in your area, you can let the sun do the work. But for most people, the solar panels have to be mounted at a 30 to 45 degree angle. Position the solar panels so it faces south. The site must have 5 to 6 hours of sunlight a day.

Get a solar controller. A solar controller, combined with temperature sensors and valve control, will provide thermostat capabilities for your hot tub. It can also turn solar off when it rains or it is night time. This adds to the cost but could be worth it especially if you use the tub a lot.

Advantages of a Solar Power Hot Tub

There are many reasons why solar power use continues to grow. Here we will demonstrate why solar power hot tubs are a big thing right now.

  • Save Money. Running a hot tub on electricity can cost up to $50 a month or $600 a year. With a solar powered hot tub you don’t have to pay that amount. You just pay for the solar equipment and that’s it, the rest is free courtesy of the sun. Moving to solar can literally save you thousands of dollars a year.
  • Environment Friendly. Solar energy is clean and renewable, a great way to cut down on carbon footprint. A clean environment is good for everyone and you don’t have to give up anything for it. If anything you will save thousands of dollars.
  • Easy to Install. if you have some knowledge of solar panels and batteries you can quickly install a solar heating system. Or you can purchase a solar heating kit and have a professional install it for you. Whichever you choose, it is convenient and you don’t have to wait long to use solar power.
  • Always Available. The idea that solar power cannot be used at night is a myth. You can use solar heating tubs anytime of the day and any season. As long as the battery is fully charged you can take a dip anytime you want. You can use either the solar panels, battery or if you are on the grid, AC power.
  • Reliable. Electricity can go out anytime, but you can always count on the sun to be there. During summer you can just relax and let the solar panels absorb the sun’s energy. No need to worry about how much you have to pay the power company, as this is free energy.

Solar Panels vs. Solar Water Heaters

You may have heard of solar waters heater being used on pools, spas and even tubs. How does it compare to a solar panel and which is more effective? Both draw power from the sun, but that is where the similarities end. Solar panels convent sunlight into electricity, while solar water heaters turn sunlight into heat.

We have covered this topic in another post, but here is a quick summary. Solar panels absorb photons (light articles) from the sun, and from the photons draw electrons. These electrons turn into electricity. Small solar panel chargers can be used to charge mobile devices, while powerful solar panels can run everything from refrigerators, AC units and hot tubs.

Solar water heaters on the other hand, do not produce electricity. Instead it converts sunlight into heat using solar collectors. These collectors resemble tubes that contain elements that convert light into heat. These are often used for swimming pools but can be applied to spas and hot tubs.

So which is better? Both are clean energy sources, but solar panels are more widely used for hot tubs. They are easier to find so it is more convenient. With the cost of solar panels going down, you can save even more money by removing your hot tub from the list of electricity dependent appliances.

In the end it is really up to you. If you can find a solar heater kit that works with your hot tub, go for it. If you decide to go for a solar panel system, that works too. Either way you will no longer have to cough up large amounts to pay the utility company every month.


The benefits of solar power continue to grow, allowing more and more appliances and deices to be run on renewable energy. One of the reasons why some are hesitant to switch to solar is they are afraid of losing the comforts of life, like a hot tub. Well that simply isn’t the case as you can be eco–friendly and relax in a hot tub.