Prioritising Solar Thermal for Maximum Efficiency
When considering solar, your first priority should be to transition your biggest energy users – hot water, swimming pool heating, underfloor heating – over from reliance on electricity, to solar thermal.
Solar thermal panels are significantly more effective and space-efficient than photovoltaic (PV) panels when it comes to heating water – typically the largest energy consumer in any household.
A well-designed solar thermal system converts as much as 90% of incoming sunlight into heat, whereas even the best PV panels only convert around 23% into electricity – and only during peak sunlight hours!
The Efficiency Gap: Solar Thermal vs. PV
Photovoltaic panels lose efficiency as they heat up.
High temperatures can reduce PV output by 10% – 25%, or around 0.5% per degree Celsius above 25°C.
PV panels are least efficient during peak sunlight hours, whereas solar thermal panels perform at their best under strong solar radiation.
A Smarter Solar Strategy
Don’t get blinded by the idea that more PV panels automatically means better energy efficiency, or sold on the idea of as many panels as you have space for!
First, reduce electricity demand by using solar thermal for heating, then assess how much PV you actually need to generate to cover the remainder of your electrical requirements.
Bottom line
It makes no sense to use electricity to heat water when solar thermal is a far more efficient and space saving solution.
In fact, solar thermal is around seven times more effective than PV for heating water.
Of course a combination of both solar thermal and PV is ideal, but in a sun-rich region like the Algarve, solar thermal should always be your first choice for heating water.