Distributed solar and wind power – Impact on distribution losses

Introducing renewable electricity as distributed generation may be an attractive option in the shift towards a more sustainable electricity system. Yet, it is not clear to what extent an increased use of distributed generation is beneficial from a systems perspective. We therefore investigate the impacts from increased employment of distributed solar and wind power on losses and transformer capacity requirements in distribution systems. The analysis is based on a dispatch model with a simple representation of typical voltage levels in the distribution system. When electricity is transferred between voltage levels, we subtract losses estimated as the transferred energy times a constant loss factor. Our results show that the losses depend on how load is distributed between voltage levels. For total penetration levels up to 40–50% on an energy basis, we find that wind and solar power could potentially reduce distribution losses. Results further indicate that solar photovoltaic capacity in the low voltage level has a limited potential to decrease peak power flows between voltage levels in a setting where seasonal variations in demand and solar output are opposite to each other. Thereby distributed solar generation also has limited potential to defer investments in transformer capacity between voltage levels.