Solar hookup question - Page 2 - Montana Owners Club

bcrvman · 10-07-2020, 01:33 PM

Quote:

Originally Posted by dallasrules

I have been working on setting up solar for my older rv and I have most of what I need. Where I am still confused is in hooking the rv into my solar set and the existing inverter in the trailer.

My solar setup is stand alone on the ground. My batteries will be in a 24v configuration. I have a 2000w inverter which I am going to run to a pedistal and plug my shore power in. I was going to let the ac side run the dc side through the converter. Otherwise, I have to have another converter to drop my battery voltage from 24v back to 12v.

I am confused about how the trailer converter works though. I know it will use the ac power to run the dc side and charge the battery that is in the trailer. I don't need that battery, or to charge it. If I disconnect the battery or take it out, will the converter still run the dc items?

I have a 2003 Montana 3655 rl. In my cedar creek, if i disconnect the battery the dc side still functions while on ac power.

I have been told that the furnace fan runs on 12v, but I can't get the furnace to work on dc power in either the Montana or the cedar creek. It does function on ac power in the cedar creek, but the montana has no ac power available at all, so I can't check.

I removed the RV converter, my inverter/charger does that job now. Why 24V, do you have issues with wire lengths?

As far as your opening question of how do you hook in the solar, the solar charger output goes to the battery bank. That's all. If you have an inverter, then it gets its input from the battery bank to produce AC. I suggest you do some research at a place like AMSolar.com or VictronEnergy.com
I am assuming you have a properly connected shunt, are using genuine deep discharge batteries like 6V Trojan T105's or Crown GC2's and a few others (always 6V)

N1282X · 10-07-2020, 01:55 PM

Tom N ohio is correct. For your 12 volt items to run properly you will have to have at least a small 12 volt battery hooked to your converter to act as a cushion as he says or an accumulator. it wouldn't have to be a large battery maybe 30 amp hours would do fine. I have thought about doing the 24 or 48 volt solar system like you are planning, victron makes a DC to DC converter to power your 12 volt period but then we run into the problem of a large load like your leveling jacks I just don't think it would be a smart move without the battery. Other than that you seem fine...

Dave10 · 10-07-2020, 01:58 PM

How did you get a trailer that is designed for 24vdc? The only reason for 24vdc solar is for running smaller guage wires which I don't think there is any significant advantage for RV and while adding extra cost for converting to 12vdc.

McRod · 10-07-2020, 03:07 PM

Dallas.

Your 2000w inverter output side should wire to a power outlet box like the picture below. You can pick up the power outlet at home depot/lowes. Mine is 50amp/20amp. You'd most likely need to get a 30amp (2000w/120v=16.6amps). Thats the max your inverter will produce on a constant draw. Then just plug in your RV to it like you normally would at an RV park.

Don't worry about the battery comments.

dallasrules · 10-07-2020, 07:37 PM

Quote:

Originally Posted by McRod

Dallas, do you have a 12v battery in those units? If you don't have a 12v power source they won't work on DC. They work on AC because your converter is on.

There are 12v batteries in both rvs. The cedar creek has on battery, but I have never had any problems. I can put out 3 slides with it. If ac power is on, the furnace works fine. If the ac is off, the furnace does not cut on.

In the Montana, there is not any ac power yet, but I have 3 125 amp agm batteries in it and the furnace also doesn't turn on.

dallasrules · 10-07-2020, 07:44 PM

I am close to having the solar up and running. Maybe this weekend. I will post back about what happens. Right now I am planning on running the inverter to a panel box and plugging the rv shore power cord into it. I am going to leave everything inside the rv as is for now which means it will keep its original lead acid deep cycle battery in place. I think its about 70 amps. I have a victron 712 battery monitor on the solar batteries, so we will see what happens. I will let you all know how it goes.

McRod · 10-08-2020, 08:24 AM

Quote:

Originally Posted by Dave10

How did you get a trailer that is designed for 24vdc? The only reason for 24vdc solar is for running smaller guage wires which I don't think there is any significant advantage for RV and while adding extra cost for converting to 12vdc.

His solar system is not on his RV. It's stand alone on the ground. The higher the voltage the further he can run his park pedestal. Most homes use 48v.

McRod · 10-08-2020, 08:26 AM

Quote:

Originally Posted by dallasrules

I am close to having the solar up and running. Maybe this weekend. I will post back about what happens. Right now I am planning on running the inverter to a panel box and plugging the rv shore power cord into it. I am going to leave everything inside the rv as is for now which means it will keep its original lead acid deep cycle battery in place. I think its about 70 amps. I have a victron 712 battery monitor on the solar batteries, so we will see what happens. I will let you all know how it goes.

Great. Remember, for now your inverter will be the Achilles heal of your system. You'll need to manage your power use to keep from popping those breakers.

dallasrules · 10-08-2020, 05:27 PM

The rv is 12v. The solar setup is 24v. I bought the setup as a whole, used. It is the inverter that is 24v, limiting my battery setup to 24v. It is an $800 inverter, so I don't want to replace it. I bought everything including most of the wiring and fuses for $1500. It had never been used. 4 250watt panels, pwm controller, 4 125 amp arm batteries, 2000/4000 watt inverter. I added a combiner box and victron 712 battery monitor.

dallasrules · 10-19-2020, 08:20 AM

I finally completed my solar setup the other day. We have ac power in the trailer now. I want to thank everyone that provided help or suggestions.

We ran our inverter to a pedistal and plugged the rv shore power cord in. We decided to disconnect the onboard battery as it says in the fuse box that the converter will run the DC from the ac and it works fine, but we don't want it to charge the onboard battery. We will maintain that separately as a backup.

We bought this setup as a whole used. The solar controller is pwm instead of mppt, so I don't think the batteries are going to get charged as high as they could, plus we only have about 3 hours of full direct sunlight this close to winter. They are getting charged to above 26 volts in a couple of days. We will check them after about a week.

McRod · 10-19-2020, 01:41 PM

Good job. After looking back on it, would you recommend an electrician do the install or easy enough for a DIYer?

dallasrules · 10-19-2020, 03:07 PM

Quote:

Originally Posted by McRod

Good job. After looking back on it, would you recommend an electrician do the install or easy enough for a DIYer?

I did it myself. I did a lot of research, asked a lot of questions, and watched a lot of videos. I am comfortable enough working with electricity. However, there are some areas I feel you could get into trouble, especially in the order you do things. I think a competent driver can handle it, but if you have doubts I wouldn't try it.

We bought a separate combiner box to make the wiring easier and because it gives a few extra layers of protection and a disconnect breaker. Also, sent dh to get 6 Guage ground wire and the guy cut #4. We used it, but that size wire is not fun to work with.

There are also wiring problems inside the rv that I have to sort out.

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