The attic room in my old house from 1909 has already been insulated twice. On the south side there is a large window about 4 m high with a terrace. Only with the shutter closed all day can this space be livable in summer, otherwise the room heats up from 37 to 38 degrees.

In winter, with the least amount of sun, I easily get 20-22 degrees without opening a radiator. Can I install air conditioning controlled by a solar panel that is not connected to the electricity grid? The room should only cool down when there is too much sun. A new window would remove the winter heat.


An installation of photovoltaic panels initially supplies direct current. With an inverter, an alternating voltage of 230 volts is realized. There are low voltage air conditioners, but they are intended for small spaces such as cars, caravans, boats, …

Due to the high heat load and the corresponding cooling capacity, a complete air conditioning system operating at 230V is required. The photovoltaic system does not supply constant power, which is dependent on sunlight. The ideal operating temperature for photovoltaic panels is ± 26 ° C. In the heat of summer, the efficiency of the photovoltaic system even drops slightly.

Due to this non-constant flow of energy, the air conditioning installation will not function in the normal way. The control between the indoor and outdoor unit can also suffer from this. Inserting a battery seems to be a solution to provide the air conditioning installation with a more or less constant current without a system connected to the network.

Then it will first store the DC current from the PV panels in the battery. It can supply a constant current. Via an inverter, you will use 230V alternating current to control the air conditioning system.

On warm days you will have some buffering with the battery, the air conditioning installation can continue to operate without there being energy production from the photovoltaic installation. All of this must be calculated. The power of the air conditioner should be adjusted to the cooling load.

The battery has to adapt to that. And depending on those parameters, the photovoltaic plant must be budgeted. And it is also not obvious that, due to this deviant control, the usual guarantees in all parts remain in force.

For the installation of the air conditioning installation, it is better to turn to a recognized refrigeration engineer. Preferably also from a company that is in your home in the installation of photovoltaic panels so that the entire installation is under the same responsibility. Either way, it is still a very unusual and quite experimental setup.