The first grid-connected photovoltaic systems were installed in the second half of the 1980s, primarily on private residential buildings (Stryi-Hipp 2005, 183). The standard feed-in tariff for solar power ranged from 6 to 10 pfennigs per kilowatt hour. This low tariff was justified on the grounds that reserve capacity should be stored for the winter period. However, some energy supply companies allowed customers to feed in power via reversible electricity meters (net-metering) (ibid). Several municipal utilities even launched support programs for photovoltaics. At the end of the 1980s, the municipal utility company Stadtwerke GieBen offered subsidies to 100 facilities of 1 DEM/W, a maximum of 1,000 German mark, as well as a feed-in payment of 10 pfennigs per kilowatt hour. Stadtwerke Saarbrucken also offered a higher compensation for solar or wind-powered electricity: a feed-in payment of 25 pfennigs per kilowatt hour for a period of 20 years. This was the highest payment in Germany at the time. The VSE Group AG (Vereinigte Saar-Elektrizitats-AG) was the first company to officially introduce a 1:1 compensation with reversible electricity meters (Stryi-Hipp 2005, 183). It became apparent at the end of 1980s that connecting the systems to the grid was a vital step for the expansion of photovoltaics in Germany.