Comparison of solar thermal and solar photovoltaic: the difference you need to know

When it comes to solar energy, two main technologies dominate the market: solar thermal and solar photovoltaic (photovoltaic).

At first glance, the two may seem quite similar – after all, they both harness energy from the sun. However, solar thermal energy and solar photovoltaic energy work differently and are used for different applications.

Knowing the key differences between these two solar energy technologies can help you determine which one is best suited to your needs.

How does solar thermal energy work?

Solar thermal systems, also called solar water heating systems, use sunlight to heat water. They consist of solar collectors, either flat plates or evacuated tubes, which absorb and retain heat from the sun. These collectors are connected to a storage tank via pipes that transfer thermal energy to heat the water inside the tank.

The hot water can then be used for a variety of household needs, from laundry and dishwashing to space heating. Solar thermal energy is ideal for supplemental water heating, reducing the electricity or gas needed to heat water conventionally.

Some of the most common uses of solar thermal energy include:

Domestic hot water heating
Heating swimming pools
Space heating
Industrial process heating

Solar thermal installations are quite affordable compared to solar photovoltaic systems, although they tend to require more space. They also work best in areas with higher direct sunlight throughout the year.

How photovoltaic solar energy works

Solar photovoltaic systems consist of solar panels containing photovoltaic cells, usually made of silicon. When sunlight hits these cells, it releases the electrons, allowing them to flow and generate a direct electric current. The solar panels are wired together to increase the voltage, and an inverter is used to convert the DC current into usable AS electricity.

This electricity can then be used to power all your usual appliances, from lights and refrigerators to televisions and computers. Any excess electricity can be fed back into the grid via net metering: solar PV systems are completely silent, have no moving parts and require little maintenance.

Photovoltaic panels produce electricity when sunlight is available on a cloudy day. The electricity generated can be stored in batteries for use at night or during power outages. Compared to solar thermal, photovoltaics have broader applications because electricity can power many different devices. However, photovoltaic systems require more initial investment and space.

Some of the most common uses of solar photovoltaic power include:

Grid-connected systems to reduce electricity bills
Off-grid cabins and campers
Backup Power Systems
Solar-powered devices like street lights and traffic lights
Agricultural water pumping systems
Telecommunications relays
Rural electrification

Main differences between photovoltaic solar and thermal solar

Now that you understand the basics of how solar PV and solar thermal work, let’s recap some of the key differences:

Application: Solar photovoltaic energy produces electricity, while solar heat is produced. Photovoltaics have broader applications, while thermal is largely limited to water heating.
Cost: Solar thermal systems are generally less expensive up front than similarly sized photovoltaic systems. But photovoltaics can generate greater long-term savings on electricity costs.
Weather dependence: Photovoltaics still generate some electricity on cloudy days, while thick cloud cover largely blocks the sunlight needed for solar thermal systems. But thermal can operate in colder weather, while photovoltaic production decreases in cold weather.
Interview : Solar thermal systems require more regular maintenance, such as checking antifreeze levels, removing scale buildup, and inspecting tubes for leaks. Photovoltaic systems are mostly “set and forget” except for cleaning any debris buildup on the panels.
Appearance : Photovoltaic panels are fully visible and cannot be hidden, while solar thermal collectors can be installed discreetly on roofs with minimal external piping.
Facility: Solar thermal systems are often easier and quicker to install than photovoltaic systems, and require less electrical wiring work.
Incentives/Taxes: Available rebates, tax credits and incentives can differ significantly between solar thermal and solar PV technology.

Is solar thermal or solar photovoltaic better for you?

Which of the two suits you best? Many people come across this question when searching solar panels Ireland.

Well, both solar thermal and solar photovoltaic systems have valid advantages and disadvantages. Which type is best for you depends on several factors:

Your costs and electricity consumption
Available installation space
Local weather and sunlight conditions
Hot water consumption and needs
Electrical Backup Needs
Aesthetic preferences
Access to the roof or ground space facing the sun

For most homes, using both technologies is the optimal scenario. A properly sized solar thermal system can meet the majority of hot water heating needs, while a photovoltaic solar panel meets electricity demand, maximizing the solar energy potential of your home or your property.


Both solar thermal and solar photovoltaic offer renewable solar energy solutions with their unique advantages. Carefully weighing factors such as costs, efficiency, applications and installation considerations allows you to select the best solar technology or combination for your needs, whether residential or commercial.

Interesting related article: “Going Solar: Is It a Smart Financial Decision for Your Business?

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