Renewable Energy Questions/Discussion > Automation, Controls, Inverters, MPPT, etc
Powerjack 8000W LF Inverter Question
solarnewbee:
Thanks Dan, useful info!
solarnewbee:
Good Day All!
I have since drafted a design for my system and pictured it below. My PJ has a built in mppt charger and I have an additional mppt. The max input is 32v so I went with the 300w 24v panels and 12 v 200ah agm batts. I was concerned about the mppt chargers interfering with each other so I will use barrier diodes to separate the 2 banks.(I may have hastily used the diode symbol in the wrong direction) my grid control is simply to jump to the local grid in case of failure without involving the inverter grid tie just using a relay and contactors at the breaker box.
I am going to test and build a few items here in the US before shipping everything. The panels and batteries were loaded at Shanghai port early this morning so that's out of the way. If you guys see an error, please point it out appreciation all around.
Also including pics of inside of my PJ and other parts.
anyone point in the right direction to post my own topic, a little lost here.
Thanks!
dan:
According to your schematic the wiring on battery bank #1 looks wrong. Why is it different from #2?
Why are you even separating the battery banks? Just because you saw 2 sets of terminals on the PJ? I'm pretty sure there are 2 sets just for convenience and those terminals are connected directly together... not meant for 2 separate banks.
Do you not have exact specs on the standalone MPPT charge controllers you will be using, and the solar panels? Despite your nicely drawn diagram, it doesn't help much without actual specifications for these things. I am curious what MPPT charge controllers you are looking at that have such a low input voltage. For example, you can get those decently cheap epsolar itracer ones which take 150v open circuit, 72v operating voltage. Other more expensive MPPT charge controllers take even higher operating voltages...
And if the banks aren't separated, then you don't need diodes. I believe most charge controllers will run fine in parallel. But do you really need 2? How much solar will you have?
solarnewbee:
I am using powerjacks 2400w mppt that's internal(I will be removing the 2 wire from charger and using the terminals on the front cover) also a separate 2.4kw mppt for bank 2 solar panels.
I will have 3000w of panels on the front roof and 3000w on the rear. The house front is situated due east and rear to the west. This setup was of the panels only was recommended by Oztules. In the Philippines we pretty much get 12 hours of sun everyday. By noon I will be at full power. My goal in a few year is to double the panels. Typhoons and rainy season is my only concern about maintaining total off-grid time although at only about 2$ a month I can keep Meralco service at hand to switch over automatically. I know the post on the pj are connected but I was afraid that the mppt controllers would interfere with each other in some way. Reading thru Oz work with pj gear I found strange things happen when well attached differently.
The battery banks were supposed to be wired the same but I was up late drawing and didn't double check before adding color. He green lines from the inverter were my way of saying I'm in green mode
dan:
Hmm yea, using different MPPTs like that may do some weird things... I really don't know though :P Different brands may have different limits or absorption times etc. I am guessing the budget is tight? I would have went with standalone charge controllers that have the nice high input voltages... but when working with 24v the amperage gets high for the amount of solar you have. The $350 MPPT I was looking at that does 3.2kw with a 48v battery bank will only do 1.6kw with a 24v battery bank. You would end up having to need at least 3, preferably 4 of these... :( That's why I like to use 48v :P
I'm guessing you already have the 8kw 24v PJ inverter purchased? If not, maybe you should go up to 48v...
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