PHY105 – Energy Equivalencies
A) Solar Equivalent of electrical Energy
Based on the actual energy usage of 8,135 Kw hr/year, calculate the required size of a solar PVC system if:
Solar insolation = 1 KW for every m2 exposure
Each panel is 1580 x 808 mm
Efficiency of PVC panel is 10%
% of days/ years when sun is out for 8 hours/day is 41%
Calculation assume perfect exposure to sun with no shade from trees and perpendicular tracking of arrays.
Solution:
The solar isolation is , and each panel has an area of:
Therefore, in a perfect exposure to sun with no shade from trees and perpendicular tracking of arrays. Each panel should generate
However, each panel is only 10% efficient, therefore, each panel will only be able to generate
Taking in consideration that in a good day, there is only 8 hour of sun light per day, therefore each panel will generate:
In the other hand, a year has 365.25 days. However, only 41% of those days’ sun is out for 8 hours, which is only 149.75 days per year. Therefore, each year, one panel will generate:
Therefore, to generate 8,135 Kw hr/year we will need
From the previous steps we now that a solar panel has an area of 1.28 m2. So, 53 panels will have an area of:
Or a roof or approximate 8.5m x 8m
B) Other energy equivalent
1. Wood heat: Using dry hard wood (oak, Ash, Maple). Assume a modern wood stove (not a fireplace) at 60 % efficiency.
For this problem we selected Red oak as our combustible, which has 24.6 Million BTU (24.6 x 106 BTU) per cord. converting this value to KW Hr. we have obtained:
However, the Wood stove is only 60% efficient, Therefore:
If we divide by the number of KW Hr need per year, we obtain
We know that a cord of wood has (4’x4’x8) = 128 cubic feet. Therefore:
2. Fuel oil. How many gallons burned by a new furnace running at 80 % efficiency
Note: Form the equivalent fuels and energy values sheet, given by the professor in the energy lab, we found out that 1 gal...