Solar PV vs. Solar Thermal Technology: What Are the Main Differences?
There are two main forms of solar power that are used by businesses and companies across the world to meet their energy needs - Solar Photovoltaic (PV) and Solar Thermal.
When it comes to sourcing eco-friendly energy, solar power has been hailed as the ideal solution. Greener, cleaner and more affordable than traditional sources of energy, moving to renewable could slash your carbon footprint and help meet the UK government’s net-zero carbon emission goal by 2050
You are likely most familiar with solar photovoltaic (PV) as it is the technology used in solar panels used on rooftops. When light hits the specially designed cells, it’s turned directly into electricity that can be used for a variety of purposes.
Solar Thermal is slightly different in that it captures solar radiation and uses it to heat water. The technology comes in various classifications from low to high and can involve the use of flat plates, mirrors and lenses to capture and concentrate the power of the sun.
Both can be used for commercial, agricultural or residential buildings, with certain advantages and disadvantages for each. So, which should you choose?
They use different technologies
Solar PV and Solar Thermal use different technologies to capture the sunlight and create energy.
Solar PV uses semi-conductive materials that have been treated with a special chemical to allow them to release electrons when exposed to light. They can be shaped into thin layers or made into solar panels of varying sizes to meet the needs and requirements of the business or household.
Solar Thermal uses sunlight to directly heat a liquid using flat plates, tubes or other similar technologies. This liquid then runs directly to your hot water storage system where it can be used when required. This is typically the methodology behind commercial solar panels.
They’re used differently
Both technologies can be used differently, depending on energy requirements.
Businesses and individuals tend to produce their energy directly from solar and use either a grid-connected or off-grid system. As the name suggests, grid-connected systems can feed the grid and be sold for profit. Off-grid systems focus on the needs of the building concerned and are usually used to heat water alongside the central heating system already in place. They can also be used for lighting, heating and other energy. In this case, both solar PV and solar thermal can be used together for optimal performance.
Power plants primarily use both PV and solar thermal to generate energy, often used via a gas turbine or steam engine. This power is then transferred to the grid for wider use.
They are different sizes
Whether you decide to adopt solar PV or solar thermal energy also depends on the space you have available. Solar Thermal occupies just a few metres squared, although you will need interior space to use this energy. On the other hand, solar PV requires much more space outside but less inside.
There is a difference in efficiency and price
Whilst it’s true to say that solar thermal costs more, its outstanding efficiency means that it converts around 90% of the radiation that it's exposed to. Solar PV requires a slightly lower initial investment but offers 20% efficiency.
However, the best results are usually achieved when using a tailor-made combination of both. You can benefit from efficiency, cost savings and greater long-term return on your investment.
Solar PV vs Solar Thermal: which should you choose?
Solar thermal is classified as 'low grade' energy since it is only useful for heating. The power generated by solar PV is vastly more versatile.
Of course, thermal energy may be stored in the hot water tank, but only for as long as it is full or hot.
Excess power from solar PV must be utilised right away, thus it must either be sent back into the grid or stored in a thermal battery to avoid being wasted. The key difference here is that for large commercial users they can sell their excess electricity back to the grid – So not wasted. For residential they typically don’t have the meters to measure export, and the electricity companies aren’t keen to purchase the electricity as the amount of export versus the administration to manage the payments doesn’t make good commercial sense to them. Previously the FiT tariff covered this, and I believe the Smart Export Guarantee will put some assumed rates in place for the residential market in the future.
Solar panels, like anything else, have distinct advantages and cons. Both are clearly fantastic pieces of equipment that will continue to aid us in our battle against climate change and move to a more sustainable lifestyle.