Renewable Energy Questions/Discussion > Automation, Controls, Inverters, MPPT, etc

Powerjack 8000W LF Inverter Question

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dan:
I am also getting a reading of about 60v N to E. Is it safe to connect them together? Or should I test with resistor first to see if there is any current flow?

Dr_Zogg, yes it is definitely possible, I know it can be done with Sma's sunny island inverters, but I do not know of any cheaper solutions

oztules:
Dan, that should be leakage from the 2 blue caps on the ac boards.... they will get a center tap voltage as they form a voltage divider across the ac to ground... it is normal.....60v for a 120v system is correct. They are small capacitance, and carry very little power.

But you can test anyway.

Connect a small 1k resistor to the ground from the neutral, and see if it gets hot, or it brings the neutral to ground potential without any heat .. then you may connect it if all ok.

It is sometimes best to leave the AC floating above ground until it connects to a switchboard, and the ground can go to bus there... ie the case is connected to neither N or A until it is forced to by the home switchboard....... this will save blowing things up if you connect back to front.. it will just work, as the transformer technically has no preference as which is active and which is neutral, until you say so.


............oztules

buglover34465:
So can I use the powerjack split phase LF inverter in L1-N-L2 connected through the dryer 220V L1-N-L@ plug to backfeed my electric box and have the normal 110V/ L1-N, or L2-N, and 220V L1-L2 on the 220v breakers (hot water heater and oven)?
From the discussion, it sounds like I can, as long as I do not use the other installed plugs. This would be nice as I currently only have a 110V inverter backfeeding L1-N, L2-N for 110V no 240V.

solarnewbee:

 I'm working on building a PJ 24 volt system and have a newbee question: can 36 volt panels be used in a 24 volt system???

Found a good deal, better than 24 volt panels. will my mppt charger deal with it?

I also find the connections on the PJ 8000w a bit confusing but in the philippines its just 220 and no earth ground, at least not until I retire there and add it for surge protection.

dan:
Solarnewbee,

By the sounds of it, yes 36v panels will work fine with an MPPT charge controller into your 24v system. You really have to just look at the max voltage of your MPPT. That's the whole point of an MPPT charge controller. Usually you even want to series your panels together and go as high as your MPPT charge controller will operate. This way you can use smaller wires (less current) and you have less losses in both the lines and sometimes in controllers/inverters, but that depends. With some charge controllers it may be best to get the input voltage as close to your battery voltage to have the best efficiency, even though it will work fine with much higher voltages. I usually just series my panels together up to the max of charge controller, this way I have less combining of parallel strings to do, if any at all. It's much easier when I series together a bunch of panels and then I can hook them straight into charge controller with no combiner box/Ys

It would help a lot to know exacts for what you are doing. For the MPPT what is the operating range voltage, max voltage, etc.? For the panels what is the Open circuit voltage, Max power voltage, etc.? I often find it silly that people call panels "12v panels" etc., since they never actually match the proper charge voltage of panels, and depending on the setup you may or may not want to use a charge controller.

If you have lead-acid batteries on a system you use often, it is often fine wiring panels straight into your batteries. If your system may sit at a full charge for a while then you probably want a charge controller. Once the batteries are full, the solar will just keep cooking them. If you are going with Lithium batteries, then you always want a charge controller. Lithium batteries will get damaged quick when overvoltaged.


As far as your inverter goes... you do not need a split phase one. Philippines is 220v 60hz L-N, and thats all. There is not two 110v L-Ns which make 220v L-L, like in the US, and which is what the split phase inverter is for. From a quick ebay search though, it looks like buying the split phase models may be the easy way to get 220v 60hz. It is perfectly fine to use it as just a 220v inverter.

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