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# Solar 5v 1.0A power supply Help Needed

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#### dpresley58

##### Newbie level 1
Hi.
I'm trying to come up with a circuit for a 5.0V 1.0A power supply driven by 2 solar cells delivering approx 6 volts @ 250mA total. Can someone steer me in the right direction?

Since you are starting with 250mA available, the best you can hope for at 5V is 250mA total.

It is likely that your load will pull down the volt level from the solar cells. If it is a computerized device it probably will not operate due to being underpowered.

Hi.
I'm trying to come up with a circuit for a 5.0V 1.0A power supply driven by 2 solar cells delivering approx 6 volts @ 250mA total. Can someone steer me in the right direction?

By 2 solar cells delivering 6V @ 250mA, so you mean that the total output of the combination of the 2 solar cells is 6V @ 250mA, or each outputs 6V @ 250mA?

Pin = Pout
Assuming input is 6V @ 250mA, Pin = (6 * 0.25)W = 1.5W. So, max Pout (with 100% efficiency) is 1.5W. So, at 5V, the maximum power you can get (assuming 100% efficiency) is 1.5W, so, (1.5/5)A = 0.3A. You can't get 1A at 5V.

Assuming input is 2 X (6V @ 250mA), Pin = 3W. So, Pout (with 100% efficiency) is 3W. So max current you can get is 0.6A. Again, you can't get 1A at 5V.

Keep in mind these are assuming 100% efficiency, and you can't get 100% efficiency practically.

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