A PVT source heat pump can be an innovative and sustainable source for supplying energy to heat pumps. A PVT panel is an advanced solar panel that produces both photovoltaic (electrical) and thermal (water/glycol) energy.
These panels provide both electrical and thermal energy, both of which are essential for the operation of a heat pump. However, it is important to note that there are different types of PVT panels on the market. Standard PVT panels are designed to dissipate the heat generated by the photovoltaic portion, often with insulation on the underside of the panels.
PVT panels suitable as a source for a heat pump are specifically designed to absorb as much heat as possible, even at the bottom, and do not contain thermal insulation.
In the simplest setup, a heat pump is considered a ground source heat pump, but the source is not ground source energy, but energy from the air extracted via the PVT panels.
A mixing valve on the source side prevents the heat pump from getting too high a source temperature. The maximum source temperature varies per heat pump brand but is usually between 20 and 30 °C. In summer, the thermal collector supplies water warmer than 30 °C, and the mixing valve mixes the cold coming back from the evaporator with the heat from the collector to stay just below the maximum permitted temperature.
The advantage over a 'normal' air/water heat pump is that no outdoor unit with fan is required, so there is no source of noise outside that could potentially be a nuisance to you or your neighbours.
This solution works best if you try to heat as much as possible during the day and possibly work with a few degrees of night reduction at night. You can also heat the tap water boiler during the day, whereby you extract most of the energy during the day, which has two advantages: during the day the outside temperature is warmer than at night, which means a better yield for the heat pump, and because you extract energy during the day, the panels cool down outside, which also means a more favourable yield for the PV panels.
As a general guideline, it is assumed that for every kilowatt of installed capacity, 5 square meters of PVT panels are needed. For a heat pump with a capacity of 6 kW, this means 6 x 5 = 30 square meters of PVT panels. Please note that this is an average, and each supplier may use their own figure.
Recently, a company had an analysis/test carried out on their PVT panels in combination with a heat pump. Over the entire year, this turned out to be a favourable solution. The test setup, with measurements by TNO, showed that a well-insulated new-build home with a capacity of 5 kW and 25 square metres of PVT panels (gross annual energy requirement 30 GJ) achieved an SPF (Seasonal Performance Factor) of 5.01, which can be considered very good.
Undoubtedly, more results will become available in the future from other PVT solutions for heat pumps. The purchase of special PVT panels is currently still expensive, as it is not a mass product and the development costs have not yet been recouped. The costs are even close to what a ground source would cost, but it is expected that this will change in the future. An additional advantage is that this installation does not fall under the requirements that are set for ground installations.
