# 24 V solar panel gives half the current of a 12 V panel [closed]

I look at solar panels for sale and notice that a 12v 250w panel gives 13.9amps while a 24v 250w gives only 6.6amp. which is why I asked if the 24v would charge my batteries as efficiently as the 12v. WHY does the 24v panel give less amps than a 12v? Simple question that nobody seems to understand. Thanks, j

• What was the specification of your old panel? Commented Aug 21, 2022 at 8:36
• Please add the part numbers or specs from both panels. Without those the simple answer is "perhaps the old panel is also 250W, and the new panel simply has more cells in series?" You may also want to include the part number of the MPPT controller, the limitation could be there.
– Drew
Commented Aug 21, 2022 at 8:44
• Thanks to all but I think my question is being misunderstood. Forget about MY panels: I look at the specs of advertised panels and a 12v 250w panel has current 13.9amps. A 24v 250w panel has current 6.60amps. WHY is that?? And does it mean less efficiency in charging my batteries?? Commented Aug 21, 2022 at 13:06
• Do you have the model names, or any spec sheet? Commented Aug 21, 2022 at 14:15
• How are you measuring said current? Commented Aug 22, 2022 at 3:39

If your old panel gave 12A at 12V, that is 144W (voltage x current). If the new one gives 6A at 24V, that also is 144W.

For the same size and performance panel, about the same output power is to be expected under similar conditions.

• Thanks Spehro..... But my question is WHY are the amps less? Am I getting less charge nto my deep cycle batteries with this new 24v panel? Commented Aug 21, 2022 at 7:03
• @JohnEltin because the panel is produced with such parameters. Commented Aug 21, 2022 at 9:01
• Specifically, solar panels are made with a matrix of cells connected in series and parallel to get the specified current and voltage. Each cell might be 3 volts and 1 amp, so you would have 12 strings with 4 cells in series each to get 12V at 12A. Or 6 strings with 8 cells in series to get 24V at 6A. Commented Aug 21, 2022 at 9:25
• Watts are volts multiplied by amps. If you double the voltage while keeping the wattage the same, the amps will halve. Commented Aug 21, 2022 at 13:10

Such is the magic of MPPT:
Since the panel starts to drop its output voltage when it is producing current, there is a magic point - depending on the solar input - where the panel produces the maximum power (voltage times current). The electronics of the MPPT push this power into your battery at the correct voltage for the present state of the battery.
Disregarding losses, the current into the battery times the voltage at the battery should equal the current out of the panel times the panels actual output voltage.