Setting up an off grid solar and battery system with generated backup

nickbatt · October 2016

I have installed a system some time ago with 22 solar panels 2 sunny boy inverters and a sunny island inverter charging 32 deep cycle batteries . there is a lister 9 kW generator as a backup . I have never got the system to work as it should and although I have made enquiries with installers nobody seems very knowledgeable about off grid systems.if anybody has answers to following I would be grateful .
1 I am unable to make sunny island charge batteries with the generator even though it will start i
2 what contacted do I need and where should it be connected to dump excess power
3 do I need to have a contactor to cut power output should generator fail to start, to prevent batteries discharging

arby · October 2016

I am a neophyte at this stuff but I do have an off grid setup with a generator backup that I put together.
On my Xantrex inverter there are two inputs for AC in. One is for Grid power and the other for Genny power. The instructions say you must use the genny input for a genny. I did this and it works fine.
2) extra power from the panels or the genny? If it's for the genny it doesn't matter. The inverter will only use what is needed to charge the batteries.
3} if your sunny island inverters have auto genny start then they will shut things off including the genny if they don't like what input they are getting.
The genny must have its own battery so I don't see why the genny would draw down your bank.

arby

arby · October 2016

On number 2-- The inverter will not charge the bank if the input from the genny is not within specs as far as voltage, frequency,and smoothness.

BB. · October 2016

For auto start gensets--Yes, somewhere there has to be failure to start shutdown. (i.e., crank for 30 seconds, turn of starter; no oil pressure, shut down, over heat shutdown, etc.).

I do not know anything about your specific controller to answer your other questions.

Is this your device/manual for your system?

https://www.solar-electric.com/lib/wind-sun/Sunny-Island-Manual.pdf

One issue can happen with Generators and Inverter-chargers--If the genset's AC voltage or frequency is out of specification, the inverter-charger will not sync up and start charging.

Have you checked the AC output of the genset for voltage and frequency?

Also, on rare occasions, the variation in genset output is quite large until there is a load on the AC output. Some folks have found placing a 100 Watt filament lamp (or other load, like a small electric heater) can stablize the genset output enough for the inverter-charger to sync.

Is your genset connected to AC 2 / Genset input? For an inverter with AC in (grid) and AC out (protected loads)--You have to have the genset (and AC line) connected to the correct locations. There is (I am guessing) an internal transfer switch inside the inverter-charger--Basically, the inverter has to be able to disconnect its inverter AC out from the AC inputs (utility power, genset)--Or else it would try to back feed those connections. If the genset is on the AC output for the inverter, it cannot manage the genset loading correctly.

And, it looks like the base inverter has a single wire Genset On/Off output--Your genset (or genset auto start controller) needs to manage all of start/run/fail itself--The SMA Sunny Island will not do that.

Where are your/system setup? Perhaps the local company that sold the SMA system (not the installer, but his supplier) can get you some help?

Sorry I am not a lot of help--But perhaps we can figure out some of your questions together.

-Bill

Setting up an off grid solar and battery system with generated backup

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