Make your Home Green

I hope you can answer this if you’re an engineer!!!?

You have been asked to design a solar water Heating System for a family of four. The family uses 100 gallons per day of Hot Water at 50 degrees Celcius. The cold water enters the house at 5 degrees Celcius. The solar collector heats the cold water to 75 degrees Celcius and stores it in an insulated storage tank until the family needs it. The sun shines for an average of 7 hours per day and provides 235 Watts per meter squared. Determine the size of the storage tank and the size of the collector.

Sattra has it dead on.

The hot water will be mixed with cold to give you 50 degrees. Simply set up:

75(X) + 5(100-X) = 50(100)
X = 64.28 gallons
Where X is the amount of hot water added to the mix

Now calculate your heat duty required per day
deltaH = (1cal/g*C)(243375.5 g)(70 C)
delta H = 17036285 calories/day

Do a conversion of the power to get your energy output from the solar panels

(235W/m^2)(.01433kCal/min*W)(60min/hr)(1000g/kg)
output = 202053 cal/m^2*hr

Multiply by your daily ration of sunshine
(202053 cal/m^2*hr)*(7hr/day) = 1414371 cal/m^2*day

And divide into your required heat duty
(17036285 cal/day)/1414371 (cal/m^2*day)

Total size of collector = 12.05m^2

Solar Hot Water Systems – Analysis Methods

Solar Heating And Cooling Of Residential Buildings $65 This manual was prepared primarily for use in conducting a practical training course on the design of solar heating and cooling of residential buildings. The text is directed toward sizing, installation, operation, and maintenance of solar systems for space heating and hot water supply, and solar cooling is treated only briefly.The solar systems described in this manual are primarily for residential applications and one- and two-story office-type buildings.This manual was developed by the staff of the Solar Energy Applications Laboratory and vocational education specialists at Colorado State University in cooperation with the NAHB Research Foundation. A national advisory committee selected from various sectors of the home-building industry, university sources, private practice, and government, was established to provide advice and general guidance.