Solar Panel Maximum Voltage Calculator – Why it’s important

solar panel maximum voltage calculator
Snow covered solar panels – not a problem on the Gold Coast however it’s important to know that the lower the solar panel temperature, the higher the voltage the panels are producing.
With a solar power system it’s very important that the solar panels match the electrical characteristics of the solar inverter or charge controller that they’re connected to. One of the electrical characteristics that’s very important is the maximum voltage the solar inverter or controller can handle, as if the voltage supplied from the solar panels is too high it won’t work and could 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 areas 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.

Note: This page deals specifically with the maximum voltages a solar power system will produce. Check out our solar panel voltage calculator page here for a calculator that covers both high and low solar panel voltage calculations.

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

REC 290W solar panel information for maximum voltage calculator
REC 290W solar panel data sheet with information highlighted that’s required for voltage calculations – click for full size image.
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.

Gold Coast Solar Power Solutions are the residential solar experts

Learn more about solar power battery storage here

Solar panel maximum voltage calculator
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16 thoughts on “Solar panel maximum voltage calculator

  • Avatar
    September 20, 2018 at 12:18 am
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    what if your power bank will be connected to solar panel and your power bank has 50v. what is the maximum voltage of panel that suits your power bank?

  • Simon Rogers
    September 27, 2018 at 6:46 am
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    Hi Ela, I would recommend installing solar panels through a MPPT charge controller, that gives you quite a lot of flexibility in regards to what solar panels you can connect to your power bank. Thanks

  • Avatar
    November 10, 2018 at 8:23 am
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    I have an MPPT 48volt solar regulator with a PV array open circuit Voltage range @48v Battery from 64-95 VDC
    I have two 24v/300watt panels in series and the open circuit voltage was 55.8(measured)Actual is supposed to be 29.76
    The regulator seems to charge my battery bank but will not go past 51.6 volt. and will not go to either bulk or float.
    Why is that.

  • Simon Rogers
    November 21, 2018 at 5:06 pm
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    Hi Fred, without knowing all the solar panel specs I can’t comment too much, however it sounds like the voltage from the panels is too low for your requirements.

  • Avatar
    November 27, 2018 at 6:02 am
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    Hi to everyone, I have one short question. Does anybody have measured notes for belowed question.
    What happens to the photovoltaic module if the voltage of string is higher than the maximum voltage of module. For example, if the voltage of string is 1400V and the maximum voltage of module is only 1000V.

    Thanks in advance

  • Simon Rogers
    November 27, 2018 at 6:32 am
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    Hi Leonard, if the solar panels are wired in such a way that the maximum system voltage is higher than the solar panels maximum voltage rating you will void the warranty of the solar panels, you risk premature failure of the solar panels and could potentially lead to a fire. You would be operating the solar panels outside of the manufacturers’ specifications, therefore all liability would fall on you. Please do not do this!

  • Avatar
    April 4, 2019 at 3:46 am
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    Hi Simon.
    I recently had a system installed on my roof. I naturally assumed that they would wire the 16 panels of each string in series giving me higher voltage but lower amps. I found out after they left they have configured each string in a series-parallel setup. 8 panels in series and in parallel to the other 8 panels. This has given me a max open circuit voltage of about 323v and open circuit current of 20.28A. I’ve got a Fronius 8.2-1 Inverter. I am a little worried that the Operating voltage of each string might be too low for inverter to operate efficiently. Can you please advise (system hasn’t been turned on by Ergon yet). Panels are Q. Cell Q5 Duo 325w. Cheers

  • Simon Rogers
    April 4, 2019 at 5:48 am
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    Hi Adam, in Australia we have a dumb rule which states that residential solar power systems are not allowed to work at a higher voltage than 600V. Nowhere else in the world has this rule! With this rule your Q Cell panels cannot be connected in a string of 16. How your panels have been wired is on the lower end of the Fronius Primo 8.2 inverters efficiency however the difference in efficiency will be very small compared to if it was wired in 1 series string of 16. I hope that helps!

  • Avatar
    April 10, 2019 at 5:22 am
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    Hi guys

    I have installed 12 x 325 watt panels my victon mppt controller is a 150/85
    The pannel voltage in load is 37.6 volt, therefore i could connect 3 x panels in series and 4 strings in parallel.

    Do i waist pannel efficiency or do i have wrong Mppt Voltage unit.

    Each string of 3 x panels is 975watt with a accumulative 8.6A

    Does it mean i have 8.6A X 4 or do i have it wrong

  • Simon Rogers
    April 10, 2019 at 10:31 am
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    Hi James you are spot on with your calculations, the best way to wire your 12 x 325W solar panels with a Victron MPPT 150/85 controller is 4 strings of 3 in series, which would give you a 112v input at 34.4A, well withing the charge controllers specifications.

  • Simon Rogers
    April 10, 2019 at 10:31 am
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    Hi James you are spot on with your calculations, the best way to wire your 12 x 325W solar panels with a Victron MPPT 150/85 controller is 4 strings of 3 in series, which would give you a 112v input at 34.4A, well within the charge controllers specifications.

  • Avatar
    April 11, 2019 at 4:27 am
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    Thanks Simon

    Question : total wattage on my setup ??

    My argument is it stay 975 Watt, but my solar supply up to 2900watt and 45 Amps to my demand of usage on inverter, 5 Kva 48volt Victron

  • Avatar
    April 18, 2019 at 4:28 am
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    Hi Simon
    I have 9 x 325w canadian panels they have 45.5v open circuit voltage and 37 volt operating voltage they are wired in 3 strings or three panels in series connected to a victron mppt 150/80 and a multiplus
    5000 48v connected to 4 x 200ah batteries my consumption is + – 8kwh per day does the combination sound right or will i have to add panels o maybe only strings of 2 panels in series your advice would be appreciated

  • Simon Rogers
    April 19, 2019 at 11:31 am
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    Hi Ian, without more site-specific information I can’t really say however roughly it sounds about right but it won’t leave any power to charge your batteries on overcast days. Personally I’d recommend an additional string of 3 panels. If you only added 2 panels you would have to rewire every other string to 2 panels as well. Just some advice, if you are using lead-acid batteries make sure they don’t get discharged too deeply as that will drastically shorten their life span. From what you have told me it sounds like your battery bank is way too small, unless you are using a battery technology such as lithium which doesn’t mind being deeply discharged repeatedly. Lead acid batteries will only last a year or so at that depth of discharge.

  • Avatar
    June 1, 2019 at 11:15 am
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    Hi, I want the clear formula for getting NUMBER OF PANELS required for 10 kW inverter.
    Please help me out

  • Avatar
    June 4, 2019 at 2:23 pm
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    Hi Chaitanya, the number of panels you need will depend primarily on the wattage output of the panels you are looking to purchase. For example, if you use 330w panels you will require just 30 (10,000/330) panels. However, if you are going to use 300w panels you will require 33 (10,000/300) panels.

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