How to deal with RV factory converter when hooking up solar

[Driggs-Dave]

I've owned a couple of travel trailers and motor homes and they didn't have first class wiring. It's difficult to get access to the wires so changing out the distribution panel is a big job for little gain. I'd leave it as is.

The original 10 gauge wire was good enough for the factory, and you haven't added any DC loads. Don't fix it if it's not broken. If you're really concerned turn on all the DC loads and measure the voltage drop in the wire.

Since the converter seems to be a switcher there's not a lot of weight so I'd leave it in place. You might wire the converter AC to the shore power side of the transfer switch so it will be powered only if shore power is connected. If you do this, it should be protected by a fuse or breaker since the shore power is usually a 30 amp circuit and the converter was probably designed for a 15-20 amp circuit.

Wiring on the AC input to the transfer switch needs to be adequate for 30 amps.

The new inverter/charger will power all the AC loads in the trailer. Might not be too good to leave the air conditioner (if you have one) on and have the inverter try to run it. Be careful, it might hurt the inverter.

Many of the inverter/chargers have a provision for a remote on/off control. I'd suggest you find a way to add an interior switch so the inverter can easily be turned off when you're not using it.

Even a 1 amp drain adds up.

[jpaton]

Installing my first solar system on a 25' travel trailer.
Only question (today) regards the factory wiring to the batteries.
Is there any reason to NOT re-install these leads directly to the batteries, (on top of the leads coming from the charge controller), so the batteries:
1) feed back to the stock DC panel, and continue to power these circuits, and
2) are charged from the RV's converter/charger when I am plugged into shore power (which probably won't be necessary since they will also be getting charged from the new solar array; but why not).

Thanks for anyone's input.

[Mike90250]

Generally PV panels are connected to a Solar Charge Controller. Several charge controllers can be connected to one battery bank. I would not connect PV panels directly to a battery.

[Skwidward]

... (on top of the leads coming from the charge controller)...

I’m gonna assume you’re referring to a solar charge controller here (bold).

If so, there’s no reason not to hook up your stock DC wiring from your RV to your new battery bank, unless you wanna replace it with something beefier-like a thicker wire to reduce voltage drop. How else are you gonna power your DC appliances?

With what I think you’re describing I would:

1. Turn the solar charge controller off when plugged into shore power. Your solar charge controller is programmable to the charging specifications of your batteries. Your RV’s converter is not. Your RV’s converter can charge them just fine. I just wouldn’t want them “competing” with each other to charge my batteries.

I keep my RV converter’s breaker switched “off,” but I also have my batteries wired to an inverter, which is wired to my RV’s AC breaker box, so I don’t want the RV’s converter thinking it’s “plugged in” and then trying to use that power (my battery power) to charge my batteries.

[littleharbor]

[QUOTE=Skwidward;n403477:

1. Turn the solar charge controller off when plugged into shore power. [/QUOTE]





If opting to turn off the charge controller you want to turn off the PV input side. Turning off the output to the batteries will be problematic as the controller will need to be re programed upon powering back up at the least, and may be damaged with PV input with nowhere to go.

Some charge controllers need to see the battery voltage to determine system voltage. Having PV input without battery already connected may cause the controller to think the system is 24 volt and whether the incoming voltage is high enough or not may try charging the batteries at 24 volts instead of 12.

[jpaton]

OK, perfect! these last (2) responses were what (I think) I was looking for.
So:
1) install a (cut-off) switch between PV and Solar charge controller to stop input to the Charge controller (and protect it). I understand that having the Solar charge controller hooked up to the PV (solar panels) without being connected to a battery bank can damage the Solar charge controller.
2) install another cut off switch between the Solar charge controller and the batteries (?). Is this necessary if I have done 1) above?

I do plan on installing an inverter, but at this time will have it stand alone (i.e. not hooked up to the AC breaker box); so, I do not think it will compete with the converter/charger.

Am I missing anything?

If no, the process to switch from 100% solar to shore power would be: 1) disconnect PV from solar charge controller 2) disconnect solar charge controller from battery bank 3) plug in RV to shore power.

Thanks everyone.

[Skwidward]

OK, perfect! these last (2) responses were what (I think) I was looking for.
So:
1) install a (cut-off) switch between PV and Solar charge controller to stop input to the Charge controller (and protect it). I understand that having the Solar charge controller hooked up to the PV (solar panels) without being connected to a battery bank can damage the Solar charge controller.
2) install another cut off switch between the Solar charge controller and the batteries (?). Is this necessary if I have done 1) above?

I do plan on installing an inverter, but at this time will have it stand alone (i.e. not hooked up to the AC breaker box); so, I do not think it will compete with the converter/charger.

Am I missing anything?

If no, the process to switch from 100% solar to shore power would be: 1) disconnect PV from solar charge controller 2) disconnect solar charge controller from battery bank 3) plug in RV to shore power.

Thanks everyone.

Sounds good to me. I use circuit breakers that have a reset button, so it can act like an on/off switch. I have one between solar charge controller and solar panels and another one between solar charge controller and battery banks.

T Tocas 150 Amp Circuit Breaker with Manual Reset, 12V- 72VDC, Waterproof (150A) https://www.amazon.com/dp/B01F76VJ3I..._L7azDbBC0SE7J

To be honest, I've accidentally turned off the battery supply to solar charge controller before shutting off the solar panels before. I gasped once I realized what I had done and quickly flicked the switch to disconnect the panels... maybe a few seconds. It didn't do any damage... thank goodness. But yeah, don't do that 😬

[Skwidward]

Sounds good to me. I use circuit breakers that have a reset button, so it can act like an on/off switch. I have one between solar charge controller and solar panels and another one between solar charge controller and battery banks.

T Tocas 150 Amp Circuit Breaker with Manual Reset, 12V- 72VDC, Waterproof (150A) https://www.amazon.com/dp/B01F76VJ3I..._L7azDbBC0SE7J

To be honest, I've accidentally turned off the battery supply to solar charge controller before shutting off the solar panels before. I gasped once I realized what I had done and quickly flicked the switch to disconnect the panels... maybe a few seconds. It didn't do any damage... thank goodness. But yeah, don't do that 😬

By the way, these breakers come in different sizes. I was merely sharing this link to show you the type of breaker I use. Size the breaker for your set up. I use the 150 amp breaker for something else. I actually use a 30 amp breaker and a 50 amp breaker either side of my solar charge controller. 👍

[ewarnerusa]

OK, perfect! these last (2) responses were what (I think) I was looking for.
So:
1) install a (cut-off) switch between PV and Solar charge controller to stop input to the Charge controller (and protect it). I understand that having the Solar charge controller hooked up to the PV (solar panels) without being connected to a battery bank can damage the Solar charge controller.
2) install another cut off switch between the Solar charge controller and the batteries (?). Is this necessary if I have done 1) above?

I do plan on installing an inverter, but at this time will have it stand alone (i.e. not hooked up to the AC breaker box); so, I do not think it will compete with the converter/charger.

Am I missing anything?

If no, the process to switch from 100% solar to shore power would be: 1) disconnect PV from solar charge controller 2) disconnect solar charge controller from battery bank 3) plug in RV to shore power.

Thanks everyone.

Sounds fine. I have both your #1 and #2 myself and the only reason I have to utilize the #2 is when reprogramming the charge controller. It requires a power cycle to initiate the new program, so after loading new program I'll disconnect via #1 followed by #2 then reconnect by #2 then #1.

But I don't think you ever need to switch between 100% solar charging to 100% shore power. The 2 different controllers will compete with each other, but no harm done since each just tapers current once it sees the voltage is at the setpoint. If your camper converter behaves like a typical WFCO model, it will only charge to 13.6V anyway. Your solar will take it to the 14.4V or 14.8V or whatever you have your setpoint at for switching to absorption stage but your converter won't care. It will likely shut off all current contribution because it is seeing the higher voltage due to the solar.

[jpaton]

Question(s) RE Circuit breakers (outlined above in post from Skwidward):

Here is an outline of my system:
400 watt solar array/40 amp solar charge controller/(2) 100 amp hour lithiums (Battle Born)/2000 watt inverter (will stand alone for now: i.e. not wired into AC panel).

What size breakers do I need for the 2 positions outlined above and between batteries and inverter:
1) Between solar panels (400 watts) and solar charge controller (40 amp).
2) Between solar charge controller and batteries.
3) Between batteries and inverter.

Do the breakers negate the need for any fuses?

Also, am I thinking about this correctly, or missing the boat somewhere?

Thank you once again Oh solar masters.

[Suprasoup]

I am assuming 4 x100w panels here. How are the panels wired to the charge controller? All in parallel? 4p? If so a fuse on EACH panel, 15a. If wired 2s2p, no fuses needed.

From charge controller to battery. 400w/12v= 33a x125% = 40a.
From battery to inverter. I am assuming a 12v system. 2000W/12V= 166a x125%= 200a

Circuit breakers can act in place of a fuse, though I prefer fuses. I would look at blue seas mrbf fuse blocks. Whatever you choose locate it as close as possible to the battery.
I would read these. use the chart for critical loads.

https://www.bluesea.com/resources/1437

https://www.bluesea.com/support/arti...t_Installation

[Wrybread]

I think you're talking about removing the converter when you supply AC power via an inverter to your wall plugs? That definitely requires disabling your onboard charger, otherwise you'll be powering your charger through your inverter.

As in your previous suggestion I just remove the blade fuse from the charger in those situations. I'm always off grid so I never reconnect it, but if I needed to reconnect I'd consider rigging up a switch.