Solar Hot Water HeaterSolar Hot Water Heater

Flat Plate Collector ProblemFlat Plate Collector Problem

A flat plate solar collector is used as a solar hot water heater. The collector area equals 20 square meters. The collector is located in a location with annual average daily solar insolation equal to 5.0 kWh/square meter/day.

1.    Calculate the amount of solar energy incident on this collector

each day.  

1.    Calculate the amount of solar energy incident on this collector

each day.  

Solar Energy =

= 5.0 kWh / sq m / day • 20 sq m = 100 kWh / day

2. Assuming that the efficiency of the solar collector and the rest of the system equals 50%, calculate the average daily energy produced (as hot water) by this system.

Express your answer in kWh/day.

2. Assuming that the efficiency of the solar collector and the rest of the system equals 50%, calculate the average daily energy produced (as hot water) by this system.

Express your answer in kWh/day. Average Produced Energy/day =

= 100 kWh / day • 0.50 = 50 kWh / day

3.  Calculate the amount of energy produced by this system each year.

Express your answer in kWh.

3.  Calculate the amount of energy produced by this system each year.

Express your answer in kWh. Annual Energy Production =

= 50 kWh/day • 365 day/year = 18,000 kWh / year

4. Assuming that the solar energy replaces the heating of hot water by electric energy and that electric energy cost 10¢/kWh, calculate the yearly savings in electricity costs as a result of using the solar hot water system. Express your answer in

$/year.

4. Assuming that the solar energy replaces the heating of hot water by electric energy and that electric energy cost 10¢/kWh, calculate the yearly savings in electricity costs as a result of using the solar hot water system. Express your answer in

$/year.

Money Saved =

= 18,000 kWh • $0.10/kWh = $1,800 / year

5. Suppose this solar hot water system were to cost $5,400 (installed). Calculate the payback

period for this system

5. Suppose this solar hot water system were to cost $5,400 (installed). Calculate the payback

period for this system Payback = Cost / Savings = $5,400 / $1,800 /year = 3 years