Your choices:
1 Comfortable indoor climate; 2 Sunshine; 3 District heating
| What is your resource? | What do you want to deliver? | What is the service the customer wants? |
| Biomass (digestible sludge) | District cooling | 1 Comfortable indoor climate |
| Biomass (fermentable sludge) | 3 District heating | Electricity |
| Biomass (solid) | Electricity | Process cooling (< 0 °C) |
| Geothermal | Fuel: Gaseous | Process heat/steam (50 - 150 °C) |
| 2 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) |
Solar heating systems for district heat applications tend to become quite big area-wise. Their production capacity will also be unpredictable since weather conditions tend to play a major role with respect to incident sunshine. Thus solar heating systems cannot be trusted for baseline production in district heating systems but may only serve as a complement to easily controllable, preferably fuel-fired, heating.
The main problem is that the maximum heat will be produced on that same day when the sun is the most intensive and when, consequently, the demand for heat will be minimal. So the solar panels included in district heating systems should basically be dimensioned so as to deliver an amount of heat equal to the demand of tap water throughout the net, plus losses.