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Solar Thermal vs Solar Photovoltaic (PV)

When considering solar, your first priority should be to transition the big energy users (water heating, swimming pool heating, underfloor heating) over to solar thermal.

Solar thermal panels are significantly more effective, and much more space-efficient, when it comes to heating water – typically the largest energy consumer in any household.

Solar thermal panels convert as much as 90% of incoming energy into heat whereas even the most efficient photovoltaic panels on the market only convert (at absolute maximum) around 23% of incoming sunlight to electricity.  

Furthermore, the hotter photovoltaic panels get, the less efficient they become. 

Hot temperatures can reduce the output efficiency of photovoltaic panels by as much as 10%-25% or 0.5 % every degree Celsius rise in temperature.

As a result, photovoltaic panels are least efficient during peak sunlight hours, whereas solar thermal panels are at their most efficient in peak solar radiation conditions.

Of course a combination of both solar thermal and solar photovoltaic panels is best, but with water heating being one of the biggest energy users in a household and solar thermal being significantly more effective and space-efficient, prioritising solar thermal is the way to go.

Don’t get blindly sold on the idea of as many photovoltaic panels as you have space for.

It simply does not make sense to generate electricity to heat water when we have this much sunshine in the Algarve.

Solar thermal should always be your primary source of heat for water.