July 03, 2025

When most people think about solar panels, they often picture them powering lights, televisions, kitchen appliances, and even charging electric vehicles. But one of the most common and practical questions homeowners ask us is: “Can solar panels heat my water?”

The short answer is no; solar PV doesn’t heat water. Or at least it doesn’t heat water in the way most people think. However, it can still play an indirect role in water heating.

That’s because most solar panels installed in homes today are solar photovoltaic (PV) systems. These systems do not produce heat. Instead, they generate electricity, which can be used to power the appliances in your home, including your immersion heater, with the addition of a hot water diverter.

So, while solar PV panels can contribute to heating water, they do so indirectly.

In this article, we will explain what that means in practical terms, why it matters, what you can expect if your considering solar for both your electricity and hot water needs, and what it means for your hot water and energy bills if you’re considering going solar.

1. What Solar PV Actually Does

Most solar systems installed on Irish homes today are solar photovoltaic (PV) systems. These systems work by converting daylight into electricity, not heat.

Solar PV systems work by converting daylight into electricity. This energy can be used to power everything in your home that runs on electricity, such as lights, fridges, cooking appliances, washing machines, dishwashers, EV chargers, and more.

And yes, even your immersion heater when paired with a hot water diverter.

This is where the misunderstanding often comes in. Solar PV panels don’t create heat themselves; they generate electricity which you can decide how to use.

So, if you’re using that electricity to power a hot water diverter and immersion heater, you’re still heating water using electricity. It’s just clean, self-generated electricity rather than electricity that you buy from the national grid.

2. Solar PV vs Solar Thermal: What’s the Difference?

This is where a lot of the confusion around heating water with solar power comes from.

When people talk about heating water with solar, they’re often thinking of solar thermal systems. This technology is entirely different from solar PV.

Solar thermal technology uses panels or tubes (often called “collectors”) that absorb heat from the sun and transfer it directly to water stored in a cylinder (source: Energy Saving Trust). This is a physical transfer of heat, not electricity. Thermal solar directly heats water, and the technology existed before solar PV. It was popular in Ireland in the early nineties, the technology has not advanced since, and has fallen in popularity as modern solar PV technology has advanced significantly.

Solar PV systems generate electricity, which makes it more versatile as it can be used for many things, including heating water with the addition of a hot water diverter. Although the outcome is the same, a tank of hot water, the methods, technology, and advantages differ significantly.

3. Why Solar PV Is More Common in Ireland

Solar thermal systems are uncommon in Ireland. That’s because solar PV systems are more versatile, as they generates electricity that can be used throughout the home, not just for hot water, delivering better overall value.

With a PV system you can power your home appliances, charge your EV and heat water with a hot water diverter – all with your solar PV system. Whereas solar thermal systems can only heat water.

The Irish climate doesn’t always provide consistent sunshine, limiting solar thermal’s benefits as it requires direct sunlight.

Solar PV systems also benefit from government grants and are more compatible with smart technologies such as battery storage, EV chargers, back-up switches and hot water diverters, allowing homeowners to maximise their savings by using every possible unit of electricity generated.

4. How Solar PV Helps with Water Heating

If you have solar PV panels and a hot water cylinder with an immersion heater, a small device called a hot water diverter can send any excess electricity from your panels to your immersion heater.

Here’s how it works:

1. Your solar system converts daylight into electricity during the day.

2. That electricity is used to power any electrical appliances in use.

3. If there is any surplus electricity, the excess is detected by the hot water diverter and redirected to your immersion heater.

4. This heats your water using your self-generated solar electricity, rather than exporting the excess energy to the grid.

A hot water diverter is an efficient way to make the most of your solar investment. But it’s important to understand that you’re still heating water with electricity. The electricity just happens to be solar generated.

Because a hot water diverter is a smart device, you can choose when to prioritise water heating. For example, in the evening before having a shower.

5. Will I Get Free Hot Water?

During the brighter months, the answer is often yes – at least during the day, or when there’s excess solar production.

Many Irish households with solar PV systems and diverters report significant reductions in the cost of heating their water. Especially during spring and early autumn when Ireland benefits from long daylight hours. However, during winter, when daylight hours are shorter, your solar system may not generate enough energy to cover all your hot water needs.

While you might enjoy free hot water for part of the year, it’s unlikely to completely eliminate your water heating costs. However, when solar power isn’t available the smart system will automatically switch your hot water back to your home’s main heating source.

6. Conclusion: A Smart Investment, Just Not “Solar Heating”

To sum up:

• Solar PV systems do not directly heat water.

• They generate electricity, which can power your hot water diverter and immersion heater (and many other home appliances).

• Solar thermal systems heat water directly using the sun’s warmth, but are becoming less common in Ireland.

• With a hot water diverter, you can efficiently use surplus solar electricity to heat your water and reduce your bills.

If your goal is to reduce electricity costs, lower carbon emissions, and make your home more self-sufficient, solar PV is a strong and flexible solution.

Just keep in mind that “solar heating” typically refers to a different technology altogether, which needs to be added on to your solar system and should be provided by your solar installer.

Bottom line: Solar PV can absolutely help with heating your hot water, just not in the way many people first assume.

Want to see how solar could benefit your home? Complete the form below to get a free solar quote and consultation tailored to your home.