Assignment task:
Assume the first year power production of a module to be 100% of the rated power of the module. The drop of power production with age of PV modules is given as linear, with a minimum of 89.6% power at 25 years. The all-inclusive price paid by the owner for a 6.4 kW system is $4000. Assume 75% of annual ac electric energy generated is used by the house itself and the remainder is fed to the utility grid. The tariff of utility grid power is 29 cents per kWh for consumption and 3 cents per kWh fed to the grid. Ignore interest rates. Assume the annual maintenance cost after the first year to be 5% of the initial capital cost. Assume one inverter replacement after 15 years. The replacement invereter cost is to be assumed as $800 for purchase and installation. Assume the life period of all other system components as 25 years.
(a) Calculate the economic benefit of having the PV array, costs and cumulative profit for each of the 25 years. Please note cost avoided is considered as an equivalent income.
(b) Plot how the net profits vary with time.
(c) What is the profit after 25 years?
(d) What is the simple payback period?
(e) What are the assumptions made in this problem that could significantly change the conclusions made regarding financial outcomes?