Your choices:
1 Sunshine; 2 Electricity; 3 Comfortable indoor climate
| What is your resource? | What do you want to deliver? | What is the service the customer wants? |
| Biomass (digestible sludge) | District cooling | 3 Comfortable indoor climate |
| Biomass (fermentable sludge) | District heating | Electricity |
| Biomass (solid) | 2 Electricity | Process cooling (< 0 °C) |
| Geothermal | Fuel: Gaseous | Process heat/steam (50 - 150 °C) |
| 1 Sunshine | Fuel: Liquid | Process heat (150 - 1000 °C) |
| Water | Fuel: Solid | Process heat (> 1000 °C) |
| Wind | Local cooling (ind. house) | Transport |
| Residual oils/fats etc | Local heating (ind. house) |
Electricity is the king of energy carriers and should generally not be used for indoor climate control.
However, it often is and in warmer climates this takes place using air-conditioning units and electrical water heaters for the production of tap water.
In case the interior climate control in a building is based on air conditioning using compressor heat pumps (the most common) and in case the building is equipped with solar cells and in case the solar cell array is equipped with an inverter so that the solar cell electricity is fed into the internal 230 V electricity net, then will the electricity produced by the solar cells contribute to maintain a comfortable indoor climate – when the sun shines. However, and due to the low efficiency with commercial solar cells and to the "dilute" nature of solar radiation – except special conditions – the electricity produced from solar cell arrays is usually not near the demands for indoor climate control.
A solar cell array may also be used for an immersion heater in the tap-water heating system. Such immersion heaters are also available for DC/24 V. The advantage, as compared to a solar panel water heater, will be the ease of installation – the disadvantage will be the price and the low efficiency.