how to heat your hot tub with solar energy

Hot tubs and spas provide a fabulous way to relax, unwind, and rejuvenate but they take a lot of energy to run. This can make them expensive to run while also potentially producing carbon emissions. Most of the energy to run a hot tub is to heat water, typically using electricity or wood. But what if you could harness solar energy to heat your hot tub? You could lower your energy costs while also making it cleaner and greener.

Solar energy is a great way to heat a hot tub!

It turns out that solar energy is actually a great way to heat a hot tub and with the right hardware it can even be a do-it-yourself installation so it doesn’t have to cost the earth to install.

In this article, we’ll go over the basics of how you can use solar energy to heat your hot tub. Lets first go over what’s needed to heat your hot tub with solar energy.

the main parts to a hot tub solar heating system:

• Solar collectors

• Pump and Controller

• Piping and Fittings

These are shown in the illustration below.

Lets go over each of these.

Solar Collectors

As you would expect, the main component of a solar heating system are the solar thermal collectors. The solar thermal collector is a device which converts sunlight (solar energy) into heat so it can heat the water from your hot tub. There are several solar thermal collector designs out there:

• Flat-plate

• Evacuated tube

• Black matting

• Prismatic

Pump and Controller

A pump is needed to circulate the water from the hot tub through the solar collectors and back to the hot tub. You can think of the pump as the heart of the system. The pump is kept on while it is sunny and heating is required. When heating is no longer required, the pump is switched off, stopping the flow of heat from the solar collectors to the hot tub.

A solar controller like the one shown on the right, can automate the whole heating process. Using a few temperature sensors to monitor 1) the hot tub temperature, and 2) the temperature of the solar collectors the controller can take the stress out of running your hot tub heating system.

Piping and Fittings

Piping and fittings are needed to carry the water from the hot tub through the solar collectors.

A variety of materials are available for piping including:

• Copper

• Steel

• Plastic

For a hot tub, plastic piping is the best choice as it is low cost, easy to install, and more than adequate for the low temperatures involved. Quick connect, push-fut style fittings like John Guest Speedfit can also really simplify the installation process.

how it works

So how does it all work?

Under sunny conditions, the solar collectors absorb sunlight and become hot. The pump is then switched on, circulating the water to be heated from the hot tub through the solar collectors. As the water is pumped through the solar collectors is heated and then returned back to the hot tub. The process continues while it is sunny and the hot tub requires heating. When heating is no longer needed, simply switch the pump off, stopping the flow of water through the system.

If a solar controller is used to measure the hot tub and solar collector temperatures, the process above can be fully automated. All you need to do is switch it on and let it take care of the rest.

SolarisKit have developed the HT100 kit which lets you install your own solar heating system for your hot tub, no experienced needed. The kit includes everything you need to start heating your hot tub with solar energy. Watch the video below to see how it works.