In order to charge 48V battery system by solar panels,4 panels each of 12V .?
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Answer:
You will need more than 48v to charge 4*12V batteries. I think the charge voltage is around 13.5V/for a 12V battery. To avoid damage to the solar cells, include a diode in the circuit so the battery doesn't discharge through the cells when it isn't bright light. I'd go for 5 cells with a current limiting voltage regulator (and the diode)
Yes, you can interconnect 4 - 12V panels together, and charge a 48V system.
Typically each panel will have it's own isolation diode, which will cause a 0.6V drop, since you have 4 of them, there will be a 2.4V drop total. You should eliminate 3 of the isolation diodes, and just use one. These are generally located inside the panels themselves. Sometimes they are external
I assume you have calculated capacities? Solar panels are rated in watts, and they will only put out the maximum wattage when the sun is clear and directly shining into them. Typically you never see the maximum for more than a short time, as the heat generated from the sun decrease efficiency on some panels, and reduces output. Clouds, sun angle, smog all reduce output. Generally you can only assume 50% output over a given day. Also batteries are not 100% efficient, meaning you can put 100 watt/hours of energy into them, and only get 80 back. There are also built in in-efficiencies in batteries, as they lose power just by sitting there. Try not to under/over rate the solar panel as opposed to the battery capacity. Small panels can not correctly charge a very large battery bank, and large panels will over charge a battery bank, unless you use a charge controller.
If you happen to have a roof line that faces south, ther are solar shingles available. These are essentually singles that are solar panels, that you place on the roof. See the link below.
Also, you can go the DC to DC converter route, where you use a single 12V panel to charge a 48V battery. You use a DC to DC converter to change the 12V to 48V. Of course you get 1/4 of the current at 48V. See the link below.
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