Final Analysis

You are almost done.

Here are some system efficiencies that you should take into account before you finalize your design:

Tolerances on solar panel efficiency ratings (A)
- Manufacturers usually give a 5% tolerance on their solar collector ratings. This means that although they say it is 12% efficient, it may actually be only 95% of that.
- Most factory ratings on solar panels are at 25^oC. As the temperature increases the efficiency decreases. It is a .45% to .55% reduction for each degree over 25^oC. If you live in a climate where the average day time temperature is greater than this, you need to account for the extra in-efficiency.
Wire losses (B)
- You need to add in the energy losses due to wire lengths. The amount depends on which wire gage chart you used (2% or 5%). This means the wire efficiency will be 95% or 98%.
Inverter efficiency (C)
- This depends on the specific inverter. Check with the manufacturer to find out the energy loss due to the power conversion. Most inverters operate at efficiencies of 80% - 90%.

Account for the system efficiency by checking your equipment sizing and selection:

Solar panels:

Combine the system efficiencies by multiplying them together (A x B x C = Total system efficiency).
Divide the total power required P_T(from step 3) by the system efficiency.
Recheck the required solar panel area calculation (steps 4 & 5).

Other Equipment:

Combine the system efficiencies but exclude the solar panel efficiency (B x C = System efficiency).
Multiply the final power generation data (wind generator, hydro generator, etc.) by that efficiency.
Check to make sure the power output is adequate to meat load demands.

Final Check

Now is the time to review your system design and make sure that everything is going to work like we hope. There are many things to think about and we can't list every one of them for you. If you have any questions don't hesitate to email us at jmitchell@epowerco.com .

Now that you have checked your design you are ready to start purchasing and installing your system. Read our installation tips before you start connecting wires.