The running voltage is 48V + 2V (see MPPT 150/70 datasheet) = 50V The modules will produce 3 * ( 18V + (-0.34% of 22.2V * -35☌ temperature difference)) = 61.9V 61.9V is higher than 50V -> that’s perfectĭoing the same thing, when the modules get warm during the day, in this case 70☌ you can see what happens: The startup voltage is 48V + 7V (see MPPT 150/70 datasheet) = 55V The modules will produce 3 * ( 22.2V + (-0.34% of 22.2V * -35☌ temperature difference)) = 74.5V 74.5V is higher than 55V -> that’s perfectĪlso running in the MPP the system would work: So if you take 3 modules SPM50-12 on a Blue Solar MPPT 150/70 in a 48V system on cold days say, -10☌ (only looking at the voltage), you can start up charging: ![]() If the cell temperature is higher or less than 25☌, this voltage reduces or increases due to the temperature coefficient, in this case -0.34%/☌ (see Blue Solar module datasheet). If you take a SPM50-12, the Open Circuit Voltage (Voc) is 22.2V and the maximum power voltage (Vmpp) is 18V at Standard Test Conditions (STC) which means 1.000W/m² irradiation, 25☌ cell temperature and an Airmass of 1.5. Of course we will also need to take a look at the minimum voltage, where the Blue Solar MPPT controller will start working. Now for the technical explanation, for those who would like to know some more details:Įxceeding the input voltage range will (as it did with the PWM controllers) damage the controller permanently. Now sizing a Blue Solar MPPT charge controller is easy!ĭownload: VE-MPPT-Calc.xlsx (744KB) – This configuration spreadsheet is compatible with MS Excel. This reduces costs to a minimum, whilst still increasing the yield!Īlso, I took the values for all our Blue Solar MPPT charge controllers and Blue Solar modules and combined them into a Spreadsheet. You can now for example add the same type of modules in parallel later without the need to change the MPPT charge controller. This Blue Solar MPPT feature is unique and makes the charge controller even more interesting! Thanks to the output power or current limiter, the output power will never exceed the maximum of the controller. In fact we can now put modules in series as well as parallel, which will also increase the input power and flexibility. Basically any module can now be used if it is within the input voltage range of the charge controller. The challenge now, is to match the PV modules to the controller, because we are not concentrating on only ‘12V’ or ‘24V’ modules anymore. For now I will look at the first part, to find out what is possible on the electrical side.īy adding a DC/DC converter in the Blue Solar MPPT controller, the system also becomes more flexible when we look at the input voltage of the controller. Sizing the system can be done electrically to see if the system is allowed and will not destroy any components, when looking at the yield to see how much energy it will produce.
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