The 7.5MW Sutton Mawr, 12MW Bishops Sutton and14.3MW Little Morton were all constructed under the Renewables Obligation subsidy regime.
Lightsource finance director Paul McCartie said: "Our continuing success in the solar industry relies on good relationships with key financial institutions like RBS.
"There remains a huge opportunity for further growth in the UK and we are delighted RBS is lending its support to us and the solar industry as a whole."
Lightsource’s current installed portfolio of 609MWp generates enough green energy for over 200,000 households in the UK.
RBS head of energy in the structured finance division Andrew Buglass added: "We have a strong pipeline of deals in UK solar project finance that we are currently working on including further larger scale projects under the Renewables Obligation."
Since its inception in the UK solar market in 2010, RBS funded more than 400MW across ground and rooftop mounted projects.
Solar parks, which are also called solar farms or photovoltaic (PV) power stations, are large-scale PV systems that supply energy into the UK national grid.
