Hi all

I have built 2x off grid cabins in the west coast. Most of it is being done adhoc as we go, so quite an ongoing learning curve with everything. This brings me to the solar that is giving me niggles and I would appreciate some advise:

 

The kit:

RCT Axpert Max 8KVA Inverter

Shoto 5.12KW battery

10x 535W panels

 

1. I have all the panels in series with 5 pointing eastish en 5 pointing to westish so that I get long exposure through the day. Im happy with the result but is this the best way or should I do 2 strings rather in parallel ?

2. Im batting to get it to accept my 5.5kw generator. Im quite confident that its a AVR issue, if genie has some load it does accept it in bits and the moment the load is off it doesnt want to know anything. Any advise on this? Firmware update on this model? Perhaps an additional AVR in line?

3. Ive read that the Axperts are useless with SOC management which I can see. I see everyone recommends the Victron BMV? Any other suggestions? Will this really help?

4. Are there any monitoring options out there that dont require a Rasberry Pi, something I can run from my PC connected to Inverter? I have a ton load of PCs lying around, id prefer to rather just use that if possible.

Also I know 1 battery isnt enough, its not lasting through the night but at this stage its not in the budget to buy another one so I have to get the system to work as efficient as possible untill that time. Im happy to start the genie or swithc entire thing off in early mornings.

 

Thanks all

 

Gian

Hey Gian, thanks for the comprehensive query. While I may not be able to answer every one of your questions, I am always more than happy to advise where I can.

 

1. You're probably better off facing the panels north if your in the Southern Hemisphere and south in the north. While you would likely get less direct sunlight in the morning/evening, you will have a more stable and consistent PV supply facing the panels north/south.

2. Sadly, not a genie guy. I know Gen-start controllers can be used in the way you are hoping to, but there is surely someone that can advise.

3. I have never dealt with a Shoto battery, there are a few things you can do. For example, if the Shoto uses "LIB" battery coms or if it is recognized by the "LIC" protocols you can use the built in coms and BMS integration just fine (Check page 18 of your manual) . However, I have seen some batteries that refuse to work with battery type set to anything other than "User Defined". In these cases there is little you can do but set it to user and make sure cutoff voltages etc are configured correctly. For the most part, you can set all of the relevant settings just fine so an external BMS may be overkill.

4. Page 65 of the manual talks about solarpower/watchpower, which is how I monitor my system. It is worth getting the the WifiMod just for that purpose. If you have the battery settings right you can still see the voltage etc which will give you an idea of the SOC. The unit is also able to communicate via a DATA USB cable, so if you set up a PC next to the inverter and run the DATA USB, solarpower will spit out most of the stats.

 

I really hope this helps in some way, otherwise I am happy to offer any further advise I can. For now, best of luck with the setup and have a great one!

Kr, Psy.

I can highly recommend SolarAssistant to manage your system - it is Pi based but is the best overall.  Don't waste your time with Watchpower. You can automate pretty much every aspect of the battery management to suit your needs.  Question is whether you have internet access at these sites though...without that remote management is not an option.  There is also a windows based inverter management software but I cannot remember the name now - it is better than Watchpower but nowhere near as user friendly as SolarAssistant.

Point 3 - If your battery is connected via cable to the inverter BMS port - RS485/CAN -  then you should have no issues with SOC monitoring, but you can also set up the inverter with option 5 USR and just program in the voltages manually. The display will not show correct SOC in this mode but you can set the shutoff voltages etc.

Wrt the generator - some here have suggested setting the unit to Appliance instead of UPS mode as this will then let the inverter be more tolerant to the voltage fluctuation.

How are you starting the gennie? Remote start? Or are you starting it manually when you are using the cabin?

On point 1 - I think you will be fine with that east west orientation - series vs parallel - not a one is better than the other answer - it depends on your inverter and how many panels and what you are trying to achieve and possible future expansion.

Your unit's specs form what I could quickly find:

Maximum PV Array Power: 8000W (4000W x 2).
MPP Range @ Operating Voltage: 90 ~ 450 VDC.
Maximum PV Array Open Circuit Voltage: 500 VDC.
Number of MPP Trackers: 2.
Maximum Solar Charge Current: 120 A.

Please post your specs from your owners manual so we can give you better answers as you state you have 10 x 535w panels - thats more than the inverter spec shows in my search.

 

Edited October 17, 20223 yr by Douw G. Gerber

1 hour ago, Douw G. Gerber said:

There is also a windows based inverter management software but I cannot remember the name now - it is better than Watchpower but nowhere near as user friendly as SolarAssistant.

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