In this article, you’ll learn about solar powered hot tubs and how to keep yours heated using the sun’s energy.
Using solar panels for hot tubs is a growing trend as people look for clean energy solutions, plus try to offset the cost of growing energy prices.
There is no single ‘best way’ to make a solar heated hot tub which means various solutions have been developed depending on your requirements.
Heating water can use a lot of electricity (and cost) so you should consider your individual situation before deciding anything. For example, available space to place solar panels, amount of sunlight, and air temperature all have an effect on the outcome.
Solar Water Heater for Hot Tub
The most efficient way to heat water with solar power is to use a solar collector. This is slightly different from a regular PV solar panel. It is a panel filled with black pipes known as ‘solar vacuum tubes’. Water circulates through the tubes which are heated by the sun and transfer heat energy into the water.
This water heating method can be used on hot tubs and swimming pools, plus is common in home water systems too. You’ll often see these solar collectors on rooftops if you look closely.
You can get pool-specific solar collectors to hook up to your hot tub. You’ll be surprised at how effective they are and will easily raise water temperature to 80℉ – 100℉. This is perfect as a hot tub water temperature should never exceed 104℉ anyway.
To use a solar water heater for your hot tub you’ll need to:
- Buy a solar pool heater – such as the SunHeater Pool Heating System.
- Mount it in a sunny location – This could be on the ground, mounting system or on a fence.
- Connect to your hot tub – Run PVC piping from the collector to the plumbing of your tub. This will be different for every spa. You can use a 3-way diverter valve to regulate flow rate, plus a check valve is useful when reintroducing heated water to avoid cycling.
Off-Grid Solar Panels
You can use solar panels to run your hot tub in order to supply it with off-grid electricity. This gives you the ability to generate electricity in a free and eco-friendly way to heat water and run jets.
This method is possible but you should be aware that it requires a significant amount of solar panels and investment. You need to generate enough electricity during 4 hours of peak sunlight each day to run your spa over a 24 hour period. And don’t forget, you must install batteries with your solar panels to store the energy and draw a consistent amount of power.
The system would work by solar panels generating electricity. This electricity is then stored in a battery. The hot tub draws power from the battery via a power inverter.
You can’t run a hot tub directly from a normal solar panel as the current would be erratic and it won’t produce electricity when there’s no sun.
So how many solar panels do you need to run a hot tub? This will be at least
1625 watts of solar panels. This is because you need enough to generate your daily energy requirements in 4 hours of peak sunlight each day.
Let’s look at an example:
The average hot tub energy usage is around 6.5kWh per day or 6500Wh (Watt-hours).
This means our solar panels need to produce 6500Wh in 4 hours.
6500Wh ÷ 4 hours = 1625 watts.
You need solar panels with at least 1625 watts output to run a hot tub.
If you’re using 200 watt solar panels that’s at least 8!
You will also need a battery system to store all the electricity you generate which will require at least 400Ah capacity.
As you can see, it is possible to use off-grid solar panels to run a hot tub. It does require significant investment and space to pull it off. You’ll need to work out your energy usage and peak sunshine for your custom setup.
Grid Tied Home Solar Panels
When you think about solar panels for hot tubs you might be thinking about it in isolation. For example, a system only connected to your spa.
In reality, it might be better to think about a wider solar array on your property. You might already have one installed that you can add too.
Home solar panels allow you to generate electricity for all your home appliances. Plus you can store excess on the main grid to use later. This is known as Net Energy Metering.
This approach can be used to keep your hot tub running without altering it directly. This is a huge benefit as you don’t invalidate the warranty. All you need to do is install enough home solar panels to cover the extra electricity used by the spa.
For example, if it uses an extra 200kWh a month, you simply need to add this energy production into your solar array. With a residential solar panel generating 1kW per day you’d need 6 or 7 off-set your tub energy usage.
Home Solar Collector Water Heater
Similar to the home solar panels, you could also link your hot tub water supply to a larger home solar collector. Just like it heats water for your main house it could provide hot water to your tub.
Combination of Solar Power to Heat a Hot Tub
One of the pitfalls of solar power is its reliability. To work effectively you need direct sunlight. In some climates, this might not be a problem, but many of us have to battle with adverse weather or regular cloud cover.
Weather like cloud cover will stop your solar array from running your hot tub efficiently. It certainly reduces the electricity or heat generated. In addition, you will generate nothing during the night.
These problems mean it is often best to use a combination of the methods above rather than relying on one. For example, you might consider keeping your hot tub hooked up to the mains with the water heater. Then use a solar pool heater to supplement heating the water. This will help to reduce electricity usage for water heating while still using mains power to run jets and lights.
Is it Worth Using Solar Panels for Hot Tubs
If you get the setup right then yes it can be worth it to use solar panels for hot tubs. At the very least, it will help to reduce your carbon footprint while still enjoying the luxuries of life. That’s a win-win situation if you ask me.
From a financial standpoint, you need to weigh up the cost of the solar installation, energy cost savings, and lifespan of all the equipment. A solar panel will have a longer lifespan than your hot tub. So think about if your spa will last long enough to make the cost savings on utility bills effective.
The exact answer is down to your situation including how much you pay for electricity and the energy usage of your equipment.
Hot Tub Warranties
One thing you might forget about is your hot tub warranty. To connect solar collectors or solar panels to your tub will require you to make alterations to the plumbing and electrics. This will instantly invalidate your warranty. This is best to avoid with expensive tubs as any problems in the future won’t be covered.
Hot tub warranties are usually 5 to 10 years long. So if you wait until after this expires you’ll probably only have a few years use left with your spa. This dramatically impacts the cost savings of your solar installation. You’re likely to need a new tub before you make your money back on the investment via reduced energy bills.
Solar Powered Hot Tub Summary
I hope this guide to solar powered hot tubs helps you in your decision making.
If you decide to use solar panels for hot tubs then take the time to work out the best solution for your equipment. Think about whether you have enough space? Do you just want to heat water or do you want electricity to run jets? And if money is a concern, then work out if you’ll actually make any savings in the long run.
Thanks for reading and happy tubbin’.
