Solar Panel Maximum Voltage Calculator – Why it’s important
With a solar power system it’s very important that the solar panels match the electrical characteristics of the solar inverter that they’re connected to. One of the electrical characteristics that’s very important is the maximum voltage the solar inverter can handle, as if the voltage supplied from the solar panels is too high or too low the inverter won’t work properly and could even be irreparably damaged.
Another important point is raised in the Australian Standard AS5033-2014 clause 3.1 which states the following:
“PV arrays for installation on domestic dwellings shall not have PV array maximum voltages greater than 600V. For non-domestic installations where the PV array maximum voltage exceeds 600V, the entire PV array and associated wiring and protection, shall have restricted access.”
With these 2 important points to consider it’s very important that we know the maximum voltage of the solar power system, and this is where our solar panel maximum voltage calculator comes in handy.
Solar Panel Maximum Voltage Calculator – How to work it out
Working out the maximum voltage that your solar power system will reach is not a straight forward thing as it requires information from the solar panel data sheet and some site specific information be entered into our solar panel maximum voltage calculator to calculate the maximum voltage the system will see. We need to take into consideration the number of solar panels connected in a series string, the minimum temperature found at the site along with the characteristics of the solar panels being used.
Let’s have a look at the information we require for our solar panel maximum voltage calculator, what it means and where you can get the information from.
Solar Panel Maximum Voltage Calculator – Information you need to know
Solar panel Voc at STC: This is the open circuit voltage the solar panel will produce at STC, or Standard Test Conditions. STC conditions are the electrical characteristics of the solar panel at airmass of AM1.5, irradiance of 1000W/m2 and cell temperature of 25oC. This information can be found from the solar panel manufacturers data sheet, please see example here.
Solar panel temperature coefficient of Voc: The voltage that solar panels work at is dependent on the cell temperature, the higher the temperature the lower the voltage the solar panel will produce and vise versa. The voltage of the system will always be at it’s highest in the coldest conditions and the solar panel temperature coefficient of Voc is required to work this out. With mono and poly crystalline solar panels it’s always a negative %/oC figure, such as -0.30%/oC on the REC Twin Peak 2 290W solar panels. This information can be found on the solar panel manufacturers data sheet, please see example here.
Minimum site temperature: This is very important and changes from site to site, for example here on the Gold Coast near the beach the lowest temperature is recorded as being 2.5oC by the Bureau of Meteorology (see here). However up at Mount Tamborine in the Gold Coast hinterland the lowest temperature is recorded as being -1.1oC by the Bureau of Meteorology (see here). We highly recommend that you check the statistics for your local area.
No. of solar panels in series string: When solar panels are wired in series strings (that is the positive of one panel is connected to the negative of the next panel), the voltage of each panel is added together to give the total string voltage. Therefore we need to know how many solar panels you intend to wire in series.
When you have all the information above you are ready to enter it into the following solar panel maximum voltage calculator to see if the solar panel design will suit your requirements. Just overwrite the data which is in the calculator – this data is for the REC 290W Twin Peak 2 solar panel used as an example above.