phang
New Member
Posts: 2
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Post by phang on Jan 3, 2017 9:28:34 GMT
Hi! I am creating a small solar panel system and I was offer a 4W output panel, thats the only size I can accept. My output will be a 9V irrigation timer which is expecting to consumes very little power. Below is my calculation on the power usage to check if the 4W panel sufficient for the timer to be powered all the time. Will need your help to verify and comment on the calculation below. Thanks!
9V Alkaline Battery
Capacity 500mAh
Controller Consumption (assumption based on 9V Akaline Battery for 2 months)
Usage per day 500mAh ÷ 60 = 8.3mAh/day
4W Panel Output
Current Output 4w / 12v = 0.333A
9 hours of Sunlight 9 * 0.333A = 2.997Ah/day
12V Lead Acid Battery
Capacity 7.2Ah, 12V
Usable Capacity, 50% 7.2Ah * 50% = 3.6Ah
Power to Controller without Sunlight 3.6Ah ÷ 500mAh = 433days
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Post by tytower on Jan 3, 2017 18:59:25 GMT
"Power to Controller without Sunlight 3.6Ah ÷ 500mAh = 433days"
500mAh is 1/2 an amp per hour? Must be something wrong there. I think you are saying 8.3mAh per day will use half the battery capacity in 433 days.Won't be much of a battery after that so you won't let that happen I suppose.
I'll let someone else comment on the maths . You have a panel putting out 1/3rd of an amp when its at its peak. For a 7.2Ah battery that should be heaps . Just depends on your input and draw now
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phang
New Member
Posts: 2
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Post by phang on Jan 4, 2017 2:35:50 GMT
"Power to Controller without Sunlight 3.6Ah ÷ 500mAh = 433days" 500mAh is 1/2 an amp per hour? Must be something wrong there. I think you are saying 8.3mAh per day will use half the battery capacity in 433 days.Won't be much of a battery after that so you won't let that happen I suppose. I'll let someone else comment on the maths . You have a panel putting out 1/3rd of an amp when its at its peak. For a 7.2Ah battery that should be heaps . Just depends on your input and draw now Yup, it is 500mAh for a normal commercial 9V alkaline battery. Because I do not know the exact power consumption for the irrigation timer, so I am assuming the 9V battery can last for 60 days.
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Post by dennis461 on Jan 5, 2017 15:01:58 GMT
This part looks wrong :-(\4W Panel Output
Current Output 4w / 12v = 0.333A
9 hours of Sunlight 9 * 0.333A = 2.997Ah/day
A 4 watt panel puts out 4 watts at high noon, aimed directly at the sun, no other time. Your average panel output over nine hours will be more like
0.5w, 1w, 2w, 3w 4w, 3w, 2w, 1w, 0.5w 17w/ 9 hours 0.16 amps leaving 1.42 ah per day
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Post by arpitkakkar1 on Jan 16, 2017 12:43:30 GMT
Thanks for the informative discussion, solar energy is used for many task like it use as generator at house held level and small solar panel use for it these panel absorb solar energy and convert it in electrical power to give power house held equipments. it is also used at commercial places lie research work. In lab all time refrigerator and other equipment should on so solar panel used to save electricity. and calculation made by researchers to on solar panels.
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