6.20. The capital cost of manufacturing and installing a 1 kWp of solar panels is 700 euros. The annual solar density in the location where the panels will be installed is 1800 kWh m-2. (a) Calculate the cost of electricity per kWh. Take the lifetime of the solar panels as 35 years and assume the discount rate is 5%. (b) What will be the cost of electricity if there is an annual maintenance charge of 100 euros?