Distributed heat generation in a district heating system

District heating (OH) systems need to be improved regarding integration of decentralised heat generation. Micro production, prosumers and smart grids are terms becoming more and more common in connection to the power grid. Concerning district heating, the development is slower, although improving. Today there are a number of such decentralised units for heat generation, mainly solar, that have been partly evaluated. Previous studies have shown that there is a need to develop a better control system for the connection to the district heating grid. In principle there are four different ways to connect a local heat generator to a OH grid. The most common technology is Return/Supply connection (R/S). In this concept it is necessary to use a feed-in pump and equipment to get correct temperatures and flows. Evaluatian of solar thermal (ST) installations in Sweden shows that the feed in flow and heat-power vary considerably; more than the heat-power productian from the ST plant. This causes a drop in heat generation from the solarthermal system. However, if the ST installation is small in relation to the OH system, it will not cause any problems for the OH system. There are more than 20 R/S ST installations in Sweden and up until recently, no complaints from OH Campanies regarding poor performance were recorded