Solar cell grades

Re: Solar cell grades

Assuming all loads are 12VDC...

Fan is 8hr * 2.29A = 18.32Ahr (don't know why you have a 12 in your equation.)

Pump is 0.5hr * 4A = 2Ahr (correct again)

For 20W of lighting at 12V the amps are 20W ÷ 12V = 1.67A. So for 8 hours you have 8hr * 1.67A = 13.36Ahr.

So your daily loads are 18.32 + 2 + 13.36 = 33.68Ahr. So your battery capacity should be around 70Ahr since you don't want to discharge below 50%.

Now take the ~34Ahr daily consumption and convert it to WattHours by multiplying by the nominal battery voltage of 12V. Then you have your daily consumption as ~400Whr.

Now accounting for a 50% overall system efficiency multiply 400Whr by 2 for 800Whr. Then with 4hr of "good" sun divide by 4 to get 200W of solar panels.

Now, will this meet the minimum charge current? 200W ÷ 14.4V (charging voltage) = ~14A. Which should be plenty. 5% of 70AH is 3.5. In fact this might be too great a current. Make sure that your charger is "smart."

I don't do these calcs for others often. I expect to be corrected.

K

Re: Solar cell grades

Well I screwed mine up and no one corrected me. I feel left out. Anyway, I goofed it - 160/12 != .83....13.3 was right.