Payback calculator      
Change the figures in yellow and press update.  
Capital Cost of renewable technology (£)  
Annual Predicted output (kWh)  
% of energy generated during day  
% of energy generated at night  
Current Electricity price / day (£ / kWh)  
Current Electricity price / night (£ kWh)  
Results    
Annual value of renewable energy / savings  
Payback (years)