Now a year since John from Petersfield's solar panel install, he has saved an enormous £359 on his £1,062 bill. His electricity usage ‘before solar’ 2009/10 was 8,246 units / Electricity usage 2010/11 ‘with solar’ was 5,459 units. Total savings of 2,787 units, at 12.8p per units, which equates to £358.97 saved.