Charging a battery via solar...

My 160W solar panels charges a 50% discharged 200Ah battery in one winters day. It did it today.
 
About 5 hours.

102Ah battery at 12V. ~50% discharged, so you need 61Ah of charge at 12V per charge.

V = Voltage [Joules of energy / Coulomb of charge]
I = Current or Amperage [Coulombs of electrons passing a point / second]

V*I = [Joules of energy / Coulomb of charge] * [Coulombs of electrons passing a point / second] = [Joules/second] = Power [Watt]

61Ah of charge at 12V = 732Wh [Watt.hours]. You have a 300W panel so minimum is 732/300 = 2.44 hours. Of course in the real world it will take longer than that - call it 5 hours. (Panel not 100% efficient, transmission losses for high current, sun not 100% the whole time)
 
I don't think that solar is really the best way to beat load shedding, expensive and all. But I must say when I first was looking into an inverter backup for load shedding I realised how expensive a simple charger is. If you don't have a built-in charger on your inverter/ups system, a solar panel is actually a viable alternative in terms of price. Like Lord Farquart said, 100ah charge in one day, that's pretty good going. A R2k charger will typically deliver 7 amps charging current so would take over 10 hours to charge his batteries.

It's difficult to say with solar as it's all dependent on your solar conditions. Typically as a rule of thumb you assume 6 hours of sunlight a day and take 80% of the solar panel's power. So if you have a 300w solar panel doing nothing but charging your battery you're looking at charging your battery on average at 300*0.8/12 = 20 amps per hour. 50% of 102 is 51 amp hours. So it's about 2.5 hours. Bearing in mind this is an average. In the morning your solar panel won't deliver much power whereas midday it will be close to it's maximum output so your mileage will vary.

Bear in mind though that you shouldn't really charge a lead acid battery this quickly, you should stick to about 10amps charge current (10% of the battery capacity)
 
contrastflash said:
I don't think that solar is really the best way to beat load shedding, expensive and all. But I must say when I first was looking into an inverter backup for load shedding I realised how expensive a simple charger is. If you don't have a built-in charger on your inverter/ups system, a solar panel is actually a viable alternative in terms of price. Like Lord Farquart said, 100ah charge in one day, that's pretty good going. A R2k charger will typically deliver 7 amps charging current so would take over 10 hours to charge his batteries.

It's difficult to say with solar as it's all dependent on your solar conditions. Typically as a rule of thumb you assume 6 hours of sunlight a day and take 80% of the solar panel's power. So if you have a 300w solar panel doing nothing but charging your battery you're looking at charging your battery on average at 300*0.8/12 = 20 [-]amps[/-]Amp.hours battery charging per hour. 50% of 102 is 51 amp hours. So it's about 2.5 hours. Bearing in mind this is an average. In the morning your solar panel won't deliver much power whereas midday it will be close to it's maximum output so your mileage will vary.

Bear in mind though that you shouldn't really charge a lead acid battery this quickly, you should stick to about 10amps charge current (10% of the battery capacity)
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ftfy

You're going to confuse someone :)
 
I also investigated solar to charge my batteries but cost was to much , so i just use the inverters built in charger, 30amps is enough to charge the batteries full in a few hours after loadsheading. I got a flashing green light on the inverter, when it flashes, is charging and when it is solid green then batteries are full. Works for me.
 
contrastflash said:
Bear in mind though that you shouldn't really charge a lead acid battery this quickly, you should stick to about 10amps charge current (10% of the battery capacity)
Click to expand...
Another ignorant comment (Edit: at the time)

If you read your battery spec sheet, it tells you the maximum charge current and recommended charge current.
Most 100Ah Lead Acid batteries are 20A.
 
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Guys look at the dates of the posts you're asking questions on and replying too.
 
Dates don't matter. One of the benefits of a tech help forum is that the discussion is not bounded by place or time. The discussion is useful for other readers. The facts still apply.
 
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Arthur said:
Dates don't matter. One of the benefits of a tech help forum is that the discussion is not bounded by place or time. The discussion is useful for other readers. The facts still apply.
Click to expand...

That's if the user is still around that is being asked a question of.
 
Not really. Still useful to dicuss and share. Other people reading up on solar charging can benefit from the thread. Even if the OP has emigrated or is defunct.
 
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