In order to make it cheaper by using less solar controller amphere. should I desing it at 24 V ?
and can I do that by connecting two 12 solar panel in series and connecting 12 volt batteries in series ?
Is there anything else that I aware of ?
Thank you.
Is my Calculation True for 60 Watt Off-Grid Lighthing ?
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Thank you very much for helping me. your answers are so usefulLeave a comment:
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EDIT: As Mike noted you DO NOT use average Sun Hours for Off-Grid, or you go dark in the winter. Use worse case.Leave a comment:
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You could use 2 12v batteries in parallel but would be better off to use 2 6v in series.
WWWLeave a comment:
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Incorrect but you are on the right track.
Where you went wrong is with your correction factor [CF] of 1.25. The CF depends on what type of Charge Controller you use. If you intend to go the very expensive route and use a PWM controller CF = 2. If you go the least expensive route and use MPPT CF = 1.5. It will take you a while to figure out why MPPT is less expensive. MPPT controllers are roughly 5 times more expensive.
So assuming you use MPPT Panel Wattage = [60 watts x 11 hours x 1.5] 4.2 hours = 235 watts. So you buy a single 250 watt GT panel and a 20 amp MPPT controller Should cost you around $500. Don't go cheap on Charge Controllers. A good 20 amp unit is $200
For PWM you would need [60 x 11 x 2] /4.2 = 315 watts. That required 3 110 watt Battery panels and a 20 amp PWM controler. That will cost you $700.
Last part is the battery. Assuming 12 volt system will require [60 x 11 x 5] / 12 volts = 275 AH. That will be 2 6-volt 275 AH battery. A decent 3 to 4 year battery will cost you roughly $400 every 3 or 4 years. An excellent choice would be a pair of Trojan T-145's
I have two question:
Could you explain please what is "5" in [60 x 11 x 5] / 12 volts = 275 AH formula ? I want 3 days reserve.
Could I use 2 X 12 Volt battery in paralel 275AH/2 = 137.5 AH ?
Thank youLeave a comment:
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I looked at the average solar radiation data from gaisma, average sun hour for los angeles is about 4,2 hoursLeave a comment:
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Where you went wrong is with your correction factor [CF] of 1.25. The CF depends on what type of Charge Controller you use. If you intend to go the very expensive route and use a PWM controller CF = 2. If you go the least expensive route and use MPPT CF = 1.5. It will take you a while to figure out why MPPT is less expensive. MPPT controllers are roughly 5 times more expensive.
So assuming you use MPPT Panel Wattage = [60 watts x 11 hours x 1.5] 4.2 hours = 235 watts. So you buy a single 250 watt GT panel and a 20 amp MPPT controller Should cost you around $500. Don't go cheap on Charge Controllers. A good 20 amp unit is $200
For PWM you would need [60 x 11 x 2] /4.2 = 315 watts. That required 3 110 watt Battery panels and a 20 amp PWM controler. That will cost you $700.
Last part is the battery. Assuming 12 volt system will require [60 x 11 x 5] / 12 volts = 275 AH. That will be 2 6-volt 275 AH battery. A decent 3 to 4 year battery will cost you roughly $400 every 3 or 4 years. An excellent choice would be a pair of Trojan T-145'sLeave a comment:
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Is my Calculation True for 60 Watt Off-Grid Lighthing ?
I want to desing 60 W off grid lighting for my garden in los angeles. and It is going to light all the night (11 hours) is my calculation true ?
Consumption = 60 Watt x 11 hours x 1.25 (safety factor) = 825 Watt.hours
I looked at the average solar radiation data from gaisma, average sun hour for los angeles is about 4,2 hours
Size of Panel =( 825 Watt.hours/ 4.2 hours) = 196,42 --> 200 Watt panel
all losses =0,85
Dept of Discharge = 0,5
3 days reserve
Size of the Battery= 825 Watt.hours / (0,85 x 0,5 x 12 Volt ) x 3 days = 485 AH Battery ---> 2 x 242 AH battery 12 Volt
Size of Controller = (200 Watts / 12V) X 1.2 (Safety factor) = 20 A solar controller
If I use 2 x 100 Watts solar panel for desinging 24 Volt system is it better ?
Thank you.
Leave a comment: