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techmuc avatar image
techmuc asked

Best SmartSolar for my situation

Hi,

A follow-up question for https://community.victronenergy.com/questions/144993/uneven-number-of-panels.html . After a lot of discussions I got a place on the wall to mount an 8th solar panel.

Current Situation:

  • 8 panels, á 150W, 22,8V Voc, 18,5V Vmp with 75 degree mounted to a balcony
  • 1 panel with shadow in the morning, 1 panel with shadow in the evening (shadow can not be avoided)
  • 48V pylontech battery ==> In worst case (battery mostly full) the panels must provide ~~55V so that the smartsolar is starting.

Question: In theory a MPPT 150/30 is sufficient (2x4 panels). The alternative is a seperate growatt MIC (without connection to my current MultiPlus), as a MPPT 250/60 is just to expensive for the expected result.

  • Is that realistic that I get the 55V "start" voltage with the shadow situation mentioned above? --> Basically, how ist the voltage behavior of panels? Will I get (more or less) the MPP Voltage in case of e.g. cloudy weather?
  • One string will have more power in the morning, the other one in the afternoon. Is a smartsolars 150/30 capable of handling that, or would I require two smartsolars?


Thanks!

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kevgermany answered ·

You have two strings of 4 panels, each string giving about 90V open circuit. In fact three panels on each string are enough to start the charge process. Once started string voltage needs to maintain battery voltage + 1, not 5. So even a panel producing zero volts won't stop the string from charging.

Shading will result in lower charge rates, but I'd expect it to be acceptable. Rather than spend money unnecessarily, suggest you install and monitor.

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techmuc avatar image techmuc commented ·

Means you would give it a try with a MPPT 150/30?

  • you are saying 90V open circuit voltage. I assumed that PV voltage is identical to MPP Voltage, not to open circuit voltage right? So I need at least 3 panels providing "full" mpp voltage.
  • My understanding was (as per the data sheet) that i need 5V to get the controller to start, afterwards 1V is sufficient. Is that incorrect?

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