Help | Maximum Solar String Voltage Formula

Can someone provide me the Solar String Voltage Calculator as I’m working on a school project and trying to figure out how to calculate those number

String voltage formula (Voc):

If we have a panel with the following specifications:

  • Assuming the minimum temperature at the site is -10°C

Max panel Voc = Voc(STC) x (1 + (Temp Coefficent x (Min Temp – 25°C))

The first step is to convert the Temp coefficient from a % to a decimal number - 0.25% = 0.0025

Max panel Voc = 39.38 x (1 + (0.0025 x (-10°C – 25°C))

Max panel Voc = 39.38 x (1 + (0.0875))

Max panel Voc = 42.83 V

Then just multiply the Max voltage (42.83 V) by the number of panels in the string!

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In laymen’s terms: when panels are connected together plus to minus (series) the voltages are added together and the size of the needed wires stay the same. When panels are hooked together minus to minus and plus to plus (parallel) the size of the wire hast to be increased. The inverter the paneles are fed into will have voltage and what maximums. You can put pairs of paneles in parallel and the connect a string of those panels in series thus not exceeding the max voltage while doubling the number of paneles.