I recently swapped my off grid system from 24v to 48v. Everything but the batteries are from Outback Power. This included rewiring my 24v Lifepo4 batteries into a series parallel configuration, buying new 48v inverters, and reprogramming my charge controllers to 48v. I've noticed my 8.7Kwh system never really gets more than 5.5Kwh output ever since swapping over a month ago. I checked the breakers at the panels and they were all fine. Only thing I can think of to check is I potentially left something unplugged in my battery shed but can't think of what.
Reduced Wattage from panels after switching from 24v to 48v
- Thread starter Warden
- Start date
When you raised the battery voltage you also raised the voltage the charge controllers will start working at. Most charge controllers need at least 5 volts above the battery voltage to start charing, Outback recommends 12-24 volts above battery voltage. If the voltage of your PV inputs is below the new higher startup voltage at some parts of the day, you could be losing production during those times. You may be able to rewire your solar panels to up the voltage. Without knowing the specs of your solar panels, how they are wired at the moment, and what charge controller you are using, I can't say for sure this is the issue, and what options you have to fix this issue.
I have noticed, with several installations, that MPPT works better with as much of a voltage difference between the array and battery bank as possible. This might be partly due to the "doesn't charge until a higher voltage" thing mentioned above. Conversion efficiency goes up with higher voltages.
As already stated, re-configure your array for higher voltage if possible.
As already stated, re-configure your array for higher voltage if possible.
I'm going to look tomorrow, I'm guessing right now I have 24v panels wired in parallel but will confirm tomorrow. Are you saying the voltage difference is a Charge Controller setting? I've got most of the settings set as recommended by the battery manufacturer, I want to say bulk is at like 56.8v
zanydroid
Solar Wizard
The voltage difference is intrinsic electrical property of how your panels are wired
24v panels wired in parallel will plain not have enough voltage to turn on with most 48v output SCCs. You would need a buck boost (reduce and increase voltage) SCC while most are buck config.
You probably need them arranged in 3s minimum then parallel those groups.
24v panels wired in parallel will plain not have enough voltage to turn on with most 48v output SCCs. You would need a buck boost (reduce and increase voltage) SCC while most are buck config.
You probably need them arranged in 3s minimum then parallel those groups.
Starting to make sense. When I measured the voltage at the solar panel bus bar/breakers I was seeing 60v in peak sun.
Solar Guppy
Red Cobra Guppy
That's your issue, not enough voltage above the battery charging voltage, you are going to need to reconfigure your solar panels
Solar Guppy
Red Cobra Guppy
Also, check the voltage at the charge controller output and compare to the batteries, you may have some voltage loss there and if so, could help by increasing the wire gauge which maybe just enough to get full harvest from the solar panels.
You were correct, I rewired my panels just now and everything is good again. Well done!
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