Diesel mini-grids are established independent power grids using (primarily) diesel reciprocating engines as the generation source. They serve remote communities, resource extraction industries, and islands in many parts of the world. These systems may have multi-megawatt power rating and the distribution mini-grid may cover a moderate geographic area (multiple settlements). Three phase ac distribution, at both low voltage and medium voltage levels, is commonly employed.

The PV hybrid opportunity is to supplement the diesel generators, thereby reducing fuel consumption. The primary motivations for installing PV are to reduce operating (fuel) costs, improve reliability and availability of power, and achieve greenhouse gas reductions and other environmental benefits.

At low penetration of PV in the mini-grid there are now relatively few technical challenges with integration - the issues are similar to conventional grid-tie PV. Instead, the needs are to make the economic and environmental case for PV, and to overcome institutional barriers. At higher penetration of PV, there is a need for cost-effective technology to maintain grid-stability since it may not be economically or technically feasible to rely on the spinning reserve capacity of the diesel generator sets to maintain stability.

225 kW PV, 3 diesel gensets operating continuously, no storage, utility operated 11 kV distribution network. (Photo: Novolta Pty.)