Solar Panel Maximum Voltage Calculator – Why it’s important
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. So how do we work this out and what do you need to know? They’re good questions and this is where our solar panel maximum voltage calculator comes in handy! One of the electrical characteristics that’s very important is the maximum voltage the solar inverter or controller can handle. That’s because if the voltage supplied from the solar panels is too high it won’t work and could be irreparably damaged.
Australian Standards PV array voltage requirements
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 points to consider it’s very important that we know the maximum voltage of the solar power system. Luckily we have our solar panel maximum voltage calculator to help!
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 – How to work it out
Working out the maximum voltage that your solar power system will reach is not a straightforward calculation. It’ll require information from the solar panel datasheet and some site-specific information to be entered into our solar panel maximum voltage calculator to calculate the maximum voltage the system will see. We need to take into consideration these 3 factors:
- The number of solar panels connected in a series string
- The minimum temperature found at the site
- 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 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 an airmass of AM1.5, irradiance of 1000W/m2, and cell temperature of 25oC. This information can be found from the solar panel manufacturers’ datasheet, please see an example here.
Solar panel temperature coefficient of Voc
The voltage that solar panels work at depends 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 its 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 datasheet, please see an example here.
Minimum site temperature
This is very important and changes from site to site. As an example here on the Gold Coast near the beach, the lowest temperature is recorded as being 2.5oC by the Bureau of Meteorology. If you head up to Mount Tamborine in the hinterland the lowest temperature is recorded as dropping down to -1.1oC. To ensure the calculations are correct please check out the weather statistics for your local area.
No. of solar panels in a series string
When solar panels are wired in series strings (that’s the positive of one panel connected to the negative of the next panel), the voltage of each panel is added together to give the total string voltage. It’s therefore important to know exactly how many solar panels you intend to wire in series.
Got it all? Great, let’s go!
When you have all the information above you are ready to use the following solar panel maximum voltage calculator. This will quickly show if your 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.
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?
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
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.
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.
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
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!
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
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!
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
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.
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.
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
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
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.
Hi, I want the clear formula for getting NUMBER OF PANELS required for 10 kW inverter.
Please help me out
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.
How can I calculate the maximum voltage of the solar panel and Inverter when design PV system?
You need to add together the maximum output voltage of the panels you are using. Depending on the configuration of the panels (series or parallel) the calculation is different. You should contact a solar expert who can calculate this for you properly and specifically for your application. Getting it wrong can cause serious damage to your inverter.
HI, i have 6 panels (180w) solar system with sma sb1100 inverter..(1000w).the inverter looks like dead no lights.electrician told me to replace the inverter and he checked the input voltage which shows 60v. he said the pannels are working.is it normal 60v.
Hi Vipi, 6 x 180W panels should be putting out a lot more than 60V if the sun is shining on them. It sounds like you have an issue with your panels. The internal diodes may have failed.
Thanks Simon..
Is this 60v enough for a 1kw inverter (SMA SB1100) to work…The inverter shows nothing on the screen…
Hi Simon,
I am currently in the process of looking at solar panels. i need some information first in regards to the components. I am looking at PV ES-POLY 290 (10 panels) to be exact. That is 2900 Watts total. I am looking at a Charge Controller, Batteries and Inverter. I am not sure what voltage i need to use? Please help
Hi Darko it all depends on what the specifications are of the products you want to use.
Hi simon
I am from pakistan..
I want to know that 1.5kw inverter whose max solar voltage is 60V, can we increase the voltage by adding more panels i to it..
What will be its effect and secondly does it will increase the efficiency??
Hi Ali, hello from Australia! I’m not completely sure I have your question right, are you looking for a solar inverter with a maximum voltage of 60V? If you add more solar panels in series the voltage of the solar array will increase, however it is very important that you wire solar panel array to suit the inverters input requirements. So if your inverter is rated at a maximum solar input voltage of 60V you want to make sure that the maximum voltage from the solar panels is no higher than this.
Hii
I have 3 x115 watt solar panels for 12 volt motorhome batteries.
Can you tell me how to calculate the VOC of the panels when connected in parallel. The VOC of each panel is 36.14v
Hi Mick if the panels are in parallel then the voltage is just the voltage of one panel, it is only in series configuration that the voltages add together. So the maximum voltage of the system would be the Voc of 36.14V adjusted for minimum temperature. If there is 3 panels wired in parallel then the current of the 3 panels will be multiplied together.
I have 6 panels 365w, voc 48.2, amp 9.2. the inverter is mpp solar 48v, 3k system, with integrated mppt, the solar max input voltage is at 145vdc. What would be the best way to connect these panels to the inverter? all in series or 3 strings inseries then paralell or what?
Hi Alberto, the only way to wire those 6 panels is 3 parallel strings of 2 panels in series. You would have to check that the inverter can handle the current input though as you would be looking at close to 30 amps. Also having 3 parallel strings the Australian Standards require string fusing be installed on the strings as well.
Hi Simon.
I have an Outback Lino 5KW inverter MMPT charger .
It states 120 – 450 VDC max input at 80 amps max.
50O VDC OCV max.PV array.
It also states 320 vdc Nominal voltage.
I intend to use 2 strings of 8 250 watt panels with an OCV of 37.4 vdc each @ 8.31 Amps = 4000 watts,
Each string would have an OCV of 29.92 say 300 volts giving me 2 x 300 x 16.62 amps.
Minimum low winter temp at daybreak rarely 0-2 C
Am i within the “Nominal voltage spec?? and is this an acceptable configuration/
hi im very new to solar, have been told to install 20 panels 330w, on both east and west and 10 due north, will that work with fronius sc primo 5kw inverter? I dont know if they put the panels in series or parallel, does it matter? will 5 panels produce enough voltage for the inverter to work? many thanks
Hi Chad, we would need to know the voltage characteristics of the solar panels in question to confirm this.
Hi Ross, that looks like a perfect setup for the Outback MPPT Charger.
Hi Simon,
My pwrgate is MPPT and specifies 30V max for the solar input. It will supply 10A max to the AGM battery. Discussion with Epic Techs about maximum Amps at solar port seem inconclusive in that the only criteria seems to be what will be DRAWN @ the charge voltage (14.4).
I wish to attach a solar system that could still supply enough Amps at low luminescence to charge the battery at the 10A maximum while not harming the unit at full luminescence, with my greatest concern being overvolting from shading.
Suggestions greatly appreciated.
Thank you SO MUCH Simon; that was exactly what I wanted to know!
Hi David, I don’t know the information about that solar controller, you would need to get it confirmed by the manufacturer that you are allowed to input more than 10A of solar into the charger.
Great to hear David, thanks for the feedback!
Hi Simon, I have 4 solar panel 345W, VOC 46V ISC 9.6A, Vmp 38V and Imp 9.1A for each panel. My hybrid inverter has PV input rating of 80VDC and 50A.
I intended to connect series-parallel which is 2 series and parallel with another 2 series. That I would have 92 VOC but 76V Vmp. Will this damage my inverter since the inverter PV rating is max 80VDC. Should we use VOC or Vmp to determine the inverter PV input ? Because although VOC is higher than my inverter max voltage rating, but solar panels are suppose to work in Vmp right ?
I know I can parallel all together to have 46VOC and 38.4A ISC because my inverter allow 50A, but my MC4 cable only can take in 1000VDC and 30A, if i connect this way my cable will overload and burn right?
Hi Jacky, if the 80V is the maximum voltage your hybrid inverter can handle you are only going to be able to do 1 panel in series and will require all 4 in parallel. With doing it this way you will have the 38.4A maximum current as you have suggested which will require the cables to be doubled up, otherwise they will be overloaded and may burn out.
Please, what’s the Imp and Isc of a 100watt/12 volt panel?
🙏
Hi Michael, sorry I have no idea what the Imp and Isc is going to be without seeing the panels datasheet. It’s probably going to be some where around 5 amps.
does anyone has a guide on how to determine system voltage ( nominal voltage) ? like 12v system for small installation less than 1200w and 24 for 1200w to 2400w, 48 for large than 2400w
Hi Festus, the actual system voltage will be whatever the system is designed for.
Hi Simon,
Should the inverter rated maximum input current be less than the rated maximum output current of a solar panel? Example if Inverter rated Max Input Current is given as 11A, would a PV configuration whose single panel Current at Max Power is rated at 12A work?
Does the Output current at Max Power imply the conditions are perfect for the solar panel setup (i.e sunlight, temperature all ideal) and in reality, the panel will rarely output the rated max current?
Hi Rade, the maximum input current of the inverter is the maximum it can handle, so the maximum output current of the solar panels should be kept below this figure. So I wouldn’t recommend what you have suggested in your example as the input current from the panels is greater than what the inverter can handle.
Gday,
Ive got 6x355w panels, voc 47.6v, isc 9.56a,vmpp 39.6, impp 8.97.
This is all new to me.
Ill be using these in an off grid 12v lithium set up.
Whats the best charge controller/s to use for this input?
2x strings in parallel?
would i need two victron 150-35 charge controllers?
Thankyou in advance.
Hi Simmon;
The specifications of the solar panels I used include only the temperature coefficient of Voc, Isc and Pmax. for the minimum number of module per string, we have to calculate the minimum Vmp that needs the temperature coefficient of Vmp. is there a way to estimate it from the parameters given in the specifications.
Thank you in advance
Hi Hassan, to calculate the minimum number of panels you really do need the Vmp voltage, as a rough guide the Vmp is usually 15-20% lower than the solar panel Voc. I hope that helps.
Hi Allan, it really depends on where you are located and what the minimum operating temperature is, saying that 3 x 47.6 Voc is 142V, that does not leave much room for higher voltages at lower temperatures on a charge controller with a maximum input of 150V so I’d recommend the 250V Victron MPPT charge controllers as a better option.
Hi Simon, one aspect of deciding on which panels to fit that confuses me still is sizing the ISC correctly. Can you tell me if this is cumulative regardless of wiring for each panel or does it follow the same rules as IM regards series and parallel connection
Hi James, thanks for your enquiry. When panels are wired in series the string current is the current of 1 panel. If you have panels connected in parallel the current is added together. For example if you had 1 string of 4 panels in series the short circuit current, or Isc, would be that of 1 panel.
If you have 3 parallel strings of 4 panels the short circuit current would be multiplied by 3.
Hi I have a new Axpert 5kva 120vdc to 450vdc , 9 x410 watt panels in series with 360voc is this fine because i was a little worried with such a high dc voltage incoming
Hi Louis, it depends on your minimum temperature on-site, however, as long as the voltage adjusted for the lowest temperature is below 450V you will be fine.
Greetings Simmon,
I have a PIP 5048mg 5 Kw 48 volt inverter (450 volts and 80 amps maximum) and 18 Trina 450 Watt solar panels. There is some shading on my roof top at different times of the day and the weather never reaches below 24c or above 35c. What in your opinion is the best setup using parallel and series? Slight confused! Thanks, John
Hi John, I’d have to know the Trina solar panels specs to work out the best setup.At an educated guess I’d say that 2 parallel strings of 9 panels in series would be the best.
Hi. what if your solar panels are wired in parallel? how would the calculation change?
Just a question on your listed topic about temperatures and voltages please forgive my stupidity but the temperatures you’ve listed at the Gold Coast would be at 3am in winter when there’s no sun wouldn’t you need to get the coldest temperature at say 9am which I couldn’t imagine on the Gold Coast was ever below 12 or so degrees ?
Hi Jamie, when panels are wired in series you add the voltages of each panel together. If it’s wired in parallel then the voltages aren’t added up, the current is added up. So say you had 4 panels, with 40 Voc and 10A Isc ratings.
If all 4 were wired in a series string it would be 160 Voc at 10A Isc.
If all 4 were wired in parallel it would be 40 Voc and 40A Isc.
If you had 2 strings of 2 panels in series it would be 80 Voc and 20A Isc.
I hope that makes sense! Please note this is just an example with round figures, I recommend taking into consideration the lowest temperatures as well.
Hi Bill, thanks for the comment and great question, it’s not stupid at all! You have a great point, the coldest temperature is usually just before dawn, and you are correct, the sun isn’t shining before dawn so is that really accurate?
According to the rather conservative Australian standards we are supposed to use the minimum temperature for each site for our calculations. The thing is even if the coldest temperature was just after dawn the amount of light falling on the panel at that time of day is very low, so the voltage the panel sees is quite low as well. Saying all that you are quite correct, this formula is very conservative, for the Gold Coast 10 to 12 degrees could realistically be used. In our business we need to comply with the Australian Standards for solar installations, so we need to use this formula for our solar panel maximum voltage calculations.