Question

Anthony wants to put solar panels on the top of his house to use to heat his water. He plans on getting a 4 foot by 10 foot flat plate collector, and is interested to see how much heat (in Btu’s) this installation would produce.

He also knows that he can expect about 6 hours each day with an average of 1 solar irradiance (1,000 W/m^2) per hour and the solar panels he is going to buy are 50% efficient at capturing the wattage.

Anthony’s main question: If the heat from a day is delivered to a 40 gallon tank of water at 55°F, what will be the water’s final temperature?

Anthony is convinced that calculating this final temperature is just a unit conversion problem, but he needs help wading through all the units. Here is what he knows:

• 1 m ≈ 3.281 ft
• 1W ≈ 3.412 Btu/hr
• 1 Btu raises 1 lb of water ≈1°F
• Water: 1 gal ≈ 8.34 lb

Answer 1