Solar/Alternator with Genset

[maynard7001]

Hello everyone,

I am sure a similar situation has been discussed at some point, but I could not find my exact scenario/question. I thought I had posted something on this , but I could not find it.

I am new to solar, but have a fairly decent understanding of logic, and electrical systems. But I do have some gaps in my understanding.

I was asked to install a new cellular module/gateway (DSE890) to work with a DSE6020 MKII Genset. This module will allow the starting and stopping of a diesel Cummins generator from a remote location. The Generator powers all systems of an off grid trailer, but the client would like to shut the system down, and just start it up prior to people being on site mostly for climate control etc....
Currently the generator runs 24/7 - 365 days per year. Lets not calculate the fuel cost on that.
The Generator integrates electrically with the Cummins engine via a harness to alternator/battery, and the DSE890 cellular module communicates via usb to the Genset(DSE6020MKII). The DSE890 also has a +/- hookup for battery power.

There is currently a standard lead acid battery for starting the diesel engine.

The mission obviously is to be able to maintain a battery level in order to keep both the DSE6020 genset controller and the DSE890 cellular module powered while the generator is off, which could be weeks at a time, in order to allow remote starting.

The modules are using 100ma for the genset, and 700ma for the cellular module. These are peak power levels, likely during transmissions and startup.

I have already purchased and installed 2 x 100W Renogy solar panels with 20A MPPT charge controller. I have also purchased a 105AH AGM battery for the solar system, but have had second thoughts about the setup and have stopped here.

Questions:

1. How can we keep the generators alternator charging the starting battery while running, but also have solar charging take over when the engine is not running, without damaging, or reducing life expectancies etc? Do we need a DC to DC charger in here somewhere?

2. Could I get away with replacing the lead acid engine battery and have 2 x AGM batteries in parallel, and hook them up to both the alternator and pv system simultaneously?

3. Do I keep the batteries separate, lead acid for engine, AGM for solar?
Should I keep these systems separate, or is there a way to wire everything together.

I'm just not certain that I can isolate the DSE6020 to use the solar battery the same way I could with the DSE890. I could also be overthinking this, as I don't suspect the engine will be off for more than 2 weeks at a time. As it stands, battery power should be adequate for several days even without charging, so adding solar would just increase the discharge time.

Any thoughts or input appreciated, and I apologize for any details that I have left out that may be relevant.
Thank you.

 

[Goboatingnow]

You can connect the solar controller in parallel with the alternator. Both will contribute charge as they can.

 

[Mattb4]

Check your SCC to insure it is a good quality one. There are many out there from China that can damage a battery over long storage times when used as a trickle charger. You should not need anything special to connect it to the genset's battery. You could get fancy and install a relay that disconnects during genset operation if having it and the alternator working in parallel bothers you.

 

[maynard7001]

The controller is from Renogy, as are the panels. 20A MPPT Rover, I believe.
Relay(s) might be a good idea, though I'm not sure of the ideal setup. Idea is to keep alternator charging batteries when in use, and have pv charging everything when genset is off. Additionally would like to have genset and gateway module powered full-time by both batteries without risk of damage.
Am I overthinking?

 

[Goboatingnow]

Yes your overthinking , don’t bother with AGMs. If you want to keep the starter charged from solar , you simply connect your mppt ( SCC) solar controller to the same starter batteries , if you need to charge another battery best get a dc dc convertor . Maybe the gateway module can run off the starter battery assuming it can handle the voltage dip during starting

KISS is best

 

[maynard7001]

That was my concern. That said, the gateway module obviously does handle the voltage drops otherwise it may not start at all...The gateway, and remote start has been confirmed working. I haven't implemented the PV charging system yet. I also entertained the idea of returning the AGM battery, and matching it with another lead acid of the same series that's in use, put them in parallel to gain some reserve power. I just thought we'd be better off with the AGM properties, and reserve power capabilities.