How to deal with RV factory converter when hooking up solar

[Skwidward]

solar is not 'wired' into a inverter/charger, only directly to the battery bank

Yeah, ok....and the battery bank is wired to the....?

[Skwidward]

I'm not sure, but I think it needs to be said:

1.) It's a "given" that the solar panels will be wired into a solar charge controller before they are wired into the inverter/charger. (If someone is actually wiring solar panels directly into a 2000 Watt inverter/charger without a solar charge controller, good luck trying to "help" them with their install through an Internet forum).

2.) My RV has a factory converter/charger. The inverter/charger with built-in transfer switch is something I picked up after buying my RV and is a main player in my solar install.

I hope this helps clear some things up.

[ewarnerusa]

I think I'm getting a clearer picture. You have an inverter/charger. This will replace the charging duties of your factory converter. You can remove the converter entirely from your system then because it won't have a job to do anymore. The inverter/charger will provide battery charge when plugged into true shore power or generator. Since you said the converter is already on a dedicated AC breaker, you could leave it in place but with AC breaker switched off and it is never doing anything but it is available as a spare charger if needed at the flip of a switch.

Solar charger controller should be wired directly to the batteries. Not as input to the inverter/charger. It seems like you disagree with this or have something else in mind. Maybe more description of what you are planning is needed. Both the inverter/charger and solar charge controller would have their own wiring to the batteries.

I'm also not sure, but think some other things should be said.
1.) The inverter/charger has the shore power AC passing through it so it knows if it is plugged into shore power/generator or not. It passes AC input through itself to your camper AC panel when plugged into shore power, just as you described. It also has its own wiring to the batteries and charges the batteries if needed when plugged into shore power/generator. It can also take DC power from the batteries via this same wiring and invert that to AC power to supply your camper AC panel when no shore power/generator AC power is present, . It does not directly interface with the solar charging system to do this, it just pulls power from the DC source which are your batteries.

2.) Your solar charging system is mainly just a battery charger. Solar panels -> charge controller -> batteries. The panels make DC current from sunlight, offer the current to the charge controller which makes decisions on how much current to pass to the batteries for charging purposes. If your DC system is drawing power, then the solar can offset the load on the battery. The charge controller sees that the voltage has dropped on the batteries and it will pass solar panel current through to help bring the voltage back up.

[Skwidward]

[QUOTE=ewarnerusa;n396404]I

[Skwidward]

I'm also not sure, but think some other things should be said.

ewarnerusa, I am so grateful for your responses. You really have been on point since I started this thread. Thank you.

To clear things up for anyone still reading that understands I will be wiring my solar panels into a charge controller but thinks that after that I'll be wiring them directly into an inverter/charger and skipping the $3,000 battery bank I purchased to store the energy harnessed from the sun by my solar panels (via a solar charge controller, of course):

Yes, solar panels -> charge controller -> batteries -> inverter/charger -> AC breaker box.

I think things got a little confusing as I tried to explain that yes, the power from my solar panels can and may, indeed, pass through my RV's converter, especially when I stated that the power from the solar panels is "wired" into an inverter/charger.

What I should have said is that the power from the solar panels will pass through my RV's converter after it first passes through a charge controller and then into my battery bank after which it then passes through my inverter/charger (installed after purchasing the RV). The inverter charger will then magically turn the DC power from the solar panels--that first passed through a charge controller and battery bank respectively before arriving at the inverter/charger--into AC power (power/energy/electricity ... I'm using the word power). This AC power is then passed (and forgive me if "passed" is not the correct word. "Wired" could be another verb to use here. I'm hoping it's clear what I'm saying, as I think of this as a route or pathway, even with AC) into my RV's AC breaker box. It is here, in the RV's breaker box, that this solar power--that has first passed through a charge controller, a battery bank, and an inverter respectively--will then pass into the RV's converter (assuming it's turned on).

Phew! Like I said, if I'd had just said that in the beginning, I might have been able to avoid the derailment of this thread. Hopefully I didn't miss anything this time. It would really be a shame if someone (NCmountainoffgrid) was to respond and tell me that it's impossible to transport the power from my solar panels to a charge controller without wires or that they're gonna need to be attached to my roof so they don't fall off when I'm driving down the road.

You may think I'm joking here, but I'm not. To me, assuming that someone reading this knows I'll be using wires to connect all these components is kinda like assuming someone reading my earlier posts knew I would be using a charge controller and a batter bank.


------

I think I'm getting a clearer picture. You have an inverter/charger. This will replace the charging duties of your factory converter. You can remove the converter entirely from your system then because it won't have a job to do anymore. The inverter/charger will provide battery charge when plugged into true shore power or generator. Since you said the converter is already on a dedicated AC breaker, you could leave it in place but with AC breaker switched off and it is never doing anything but it is available as a spare charger

Exactly

[ewarnerusa]

Ok. Sounds like you're on track! Best practice is to install your inverter and solar charge controller as close to the batteries as possible to minimize DC wire length. Wire resistance results in voltage drop on the DC side.

[Ampster]

solar is not 'wired' into a inverter/charger, only directly to the battery bank

If the inverter is wired to the battery and the solar is wired to the battery through the controller, one might consider them wired to a common buss. Other than a disconnect or fuse is there much difference from an electrical perspective?

[NCmountainsOffgrid]

not sure what you're asking.... but from a typical 'RV' installation or addition of solar, the wiring from the panel to the solar controller to the battery bank is all that there is.

the Inverter only 'uses' battery power, just like your 12v Fuse panel does.

in other words, the Solar power simply recharges your battery bank, as the Inverter and the 12v systems 'use' the battery power

while there are some 'hybrid' inverters, which can combine the input of the solar to offset incoming 120v Shore Power, to save on utilities cost, the majority of RVs simply attach the solar directly to the battery bank. and while solar power 'can' directly power 12v devices, lights, fans, and appliances, the issue is that once the sun goes down, or clouds come out, or you park under shade, those devices now have no power, unless you run some type of additional wire to each one, giving it both direct Solar, and power from the 12v system(batteries)(?).

[Ampster]

not sure what you're asking.... but from a typical 'RV' installation or addition of solar, the wiring from the panel to the solar controller to the battery bank is all that there is.

.....

I was just trying to clarify what has been said earlier that the battery, charge controller and inverter are all connected together. There are probably several wiring schemes but electrically the result is the same.

[Skwidward]

Ok. Sounds like you're on track! Best practice is to install your inverter and solar charge controller as close to the batteries as possible to minimize DC wire length. Wire resistance results in voltage drop on the DC side.

Absolutely. The battery bank, inverter/charger, and charge controller will all be within 1-2 ft of each other with 2/0 wire between them and appropriate breakers and shut off switches.

My biggest issue with designing this system has been the run from battery positive to the DC panel. The factory wire (that came with the RV) runs from the "short stop" 20 amp breaker on the tongue to the DC fuse panel and is 10 awg wire. It is soldered into the DC fuse panel and has a 30 amp blade fuse.

So one option is to just run a wire with an appropriate breaker/fuse from battery positive to the short stop and utilize the 10 awg factory wire already in place. I think this is doable, as I will not be drawing any more amps from the DC fuse panel than the factory system was designed to handle, despite the large increase in battery bank (300 ah) and the installation of a 2000 Watt inverter/charger.

At first I was considering replacing the factory 10 awg wire with something a little more heavy duty, like 2-6 awg, in order to reduce voltage drop, as this run is roughly 12-14 feet. However, in order to do this, I would either have to hope that I can remove the old 10 awg soldered wire from the DC fuse panel and the the new, larger wire will fit if I solder it in....or I could just replace the DC fuse panel with a new one that excepts lugs and, therefore, larger gauge wire.

This is why I started thinking about just removing that "leg" (Battery positive to DC fuse panel) from the whole system. My thinking was that the inverter/charger will supply the AC power to the RV's AC breaker box, and the RV's converter will convert the AC power to DC and then supply it to the DC fuse panel (just like if I was plugged in at a park). I won't have to worry about the converter trying to charge the battery with the battery's own power, as I will have removed that "leg." The problem with this is that I will always have to have the converter and inverter turned on in order to use DC power. Also, the RV converter draws like 8 amps. So, it seems more sensible to just turn the RV's converter off to avoid this, but this brings me back to use the above dilemma regarding that run from battery positive to the DC fuse panel regarding the 10 awg wire.

[Skwidward]

not sure what you're asking....

Correct me if I'm wrong, but I think he's asking if you possess the neural faculties for abstract thought.

An analogy of the concept in his question might be: when you turn on a faucet on in your house to fill a bath tub the water comes out of the faucet, but you may consider that the water filling your bath tub 'really' comes from the local water tower.

...but from a typical 'RV' installation or addition of solar, the wiring from the panel to the solar controller to the battery bank is all that there is.

Unless you wire an inverter/charger with built-in transfer switch to the battery bank, wire your shore power plug to your inverter/charger's "AC in" port, and wire your inverter charger's "AC out" to your RV's AC breaker box..... I guess this would be considered a "non-typical" installation or addition of solar? Maybe that is what's confusing you.

the Inverter only 'uses' battery power, just like your 12v Fuse panel does.

My inverter/charger with built-in transfer switch uses less than 1 amp/hr 12V power, yes.

in other words, the Solar power simply recharges your battery bank, as the Inverter and the 12v systems 'use' the battery power

Just to make sure we're on the same page: Yes, the solar power recharges your battery bank, and yes, the inverter and 12V fuse panel use that "battery" power. However, the inverter will also invert the "battery" power into AC 120V power and supply it to the RV's AC breaker box as if it were mimicking shore power. Also, when plugged into shore power the inverter/charger will allow the AC power from the shore power to "flow" through it to the AC breaker box in the RV, and it will also, thanks to it's built-in transfer switch, use some of that AC shore power to charge the battery bank.

while there are some 'hybrid' inverters, which can combine the input of the solar to offset incoming 120v Shore Power, to save on utilities cost, the majority of RVs simply attach the solar directly to the battery bank. and while solar power 'can' directly power 12v devices, lights, fans, and appliances, the issue is that once the sun goes down, or clouds come out, or you park under shade, those devices now have no power, unless you run some type of additional wire to each one, giving it both direct Solar, and power from the 12v system(batteries)(?).

I'm really not too sure what you're talking about here.

I do understand if I lay one of my solar panels so that the sun is shining on it and then wire this same solar panel directly to a light bulb--and by 'directly' I mean positive wire directly from the solar panel to the positive terminal on the light bulb and the negative wire directly from the solar panel to the negative terminal on the light bulb--the light bulb will light up. If, however, I cover the solar panel so that it is shaded from the sun, that light bulb will go out.

This why when designing my solar installation I purchased 3x 100 ah lithium batteries. The plan is that these batteries will store the energy harnessed from the sun via the solar panels and........I'm gonna stop here, because I really don't think I have the energy (non-solar energy) to explain that this energy from the sun harnessed by the solar panels will pass through a solar charge controller before being stored in the batteries, again...

[zamboni]

Skwidward: Wow, this thread got wild, huh? I have three thoughts about your original question:

• I may have gotten turned around by all the over-explaining above, but it kinda sounds like you're asking in your OP if you should eliminate the connection between battery and DC fuse panel (currently via the same wires that the stock converter uses to charge), and instead let the inverter power the converter and thereby energize your DC fuse panel. This will work -- nothing will explode -- but it's so inefficient that you might as well consider it a non-option.
• Your observation that the connection from battery to stock converter (and thus the DC panel) is long and undersized sounds spot on. I had a similar situation. Folks are telling you that you can leave the stock converter in place and use it as a backup charger, but given the long run, small cable, and low sophistication of these converters, this will almost certainly result in chronic under-charging (ie early death) of your batteries. If you're hellbent on having a "backup" shore charging solution, then okay yeah it's better than nothing. Personally, i think carrying a 20-lb. "spare" converter is overkill on an RV, given that the whole rig is inherently portable and you can always stay at a motel if something actually does break
• I think you will be happiest removing the stock converter, pulling properly-sized cable to the DC fuse panel from the battery, and routing all shore power through the inverter/charger (as you describe in your last post). In this way, AC power will always "just work" regardless of where the power is coming from, your DC loads will work efficiently, and your batteries can get a nice healthy charge from shore power (via the inverter/charger, which is almost definitely more sophisticated than the stock converter, and not connected with miles of 10awg). My system is configured this way and it's been very convenient. Since you've already paid for the inverter/charger, it seems a waste to not take advantage of its capability.

P.S. Are your AC breaker box and DC fuse panel really two separate things, in two different locations? I have not seen that before; usually they are combined into one enclosure.
P.P.S. Do you use a Mac? I've found this forum software hates punctuation when coming from a mac, and will truncate posts at the first apostrophe. It's so infuriating to have to write like a child that I've completely stopped using the forum from home. At least i have a PC for work.

- Jerud
------------------------------------------------------------
1220W array / 1000Ah LFP house bank
MidniteSolar Classic 150, Magnum MS2812
ME-RC, Trimetric, and JLD404
Full-time 100% electric boondocking (no propane, no genny) since 2015
2001 Fleetwood Prowler 5th wheel 25 foot, self-rebuilt
www.livesmallridefree.com

[Skwidward]

Skwidward: Wow, this thread got wild, huh?

I was really starting to wonder if I had gone crazy

]...it's so inefficient that you might as well consider it a non-option.

I agree. My thinking has evolved since the OP. I was originally trying to think of how I could avoid replacing the DC fuse panel and the 10 awg wire to the battery.

P.S. Are your AC breaker box and DC fuse panel really two separate things, in two different locations? I have not seen that before; usually they are combined into one enclosure.

They are in the same box with the converter kinda in between them. I attached photos.

P.P.S. Do you use a Mac? I've found this forum software hates punctuation when coming from a mac, and will truncate posts at the first apostrophe. It's so infuriating to have to write like a child that I've completely stopped using the forum from home. At least i have a PC for work.

I use a chrome book and have had it wipe posts on other forums too. It's pretty frustrating.

So I'm down to two options right now:

1. Utilize the already in-place 10 awg wire from the battery positive to the DC fuse panel and just turn the converter off using the breaker switch indefinitely. (easiest option but possibly less efficient).

2. Replace the existing soldered DC fuse panel with one that can accept lugs and run new, larger awg wire from battery positive to the new DC fuse panel. Disconnect the converter from both AC and DC fuse/breaker panels and pretend it doesn't exist.

By the way, the existing DC fuse panel only has positive wires connected to it. All the negative wires from the DC appliances run to a bus bar (not seen in the photos) that is loose behind the breaker box and then to chassis ground. Regarding the positive and negative DC wires that come "out" of the converter: the positive (yellow in the photo) runs to the DC fuse panel (the orange 40 amp blade fuse in the photo) and the negative (white) runs straight to the loose DC negative bus bar I just mentioned. So, if I replace the DC fuse panel, I will be able to eliminate this "floating" DC negative bus bar and just attach all DC appliance negatives to the new fuse panel and then run a main negative to chassis ground.

600 Watts of solar
150/35 MPPT charge controller
2000 Watt inverter/charger
300 ah lithium battery bank

Given my planned set up, what kinda size wire would think would be appropriate to run from my battery positive to the DC fuse panel? (The run would be about 12 feet).

[NCmountainsOffgrid]

after reading some of your original ideas, I think that whats missing is that no Converter, on it's own breaker, is part of the equation with the Inverter's output - simply, the Inverter is only designed for 'some' circuits, not all, and not including the Converter, the Air Conditioner(s), the electric Water Heater, the engine Block Heater, or any 'large draw' appliances or devices not intended to be powered by the Inverter - the SUB PANEL for the Inverter's output takes care of only the circuit it is intended to power. Some inverters are small and only designed and wired to one or a few dedicated items, while others are 'whole house' inverters, with integrated battery Chargers, to handle the charging and the output to most, or all, outlets, in a single unit. These will have a breaker output in your Main panel to supply the 120v Shore or Gen power, and will have a sub-panel for the return power from the Inverter when it is providing power, or passing-thru Shore or Gen power.

So, that being said, you don't ever have to worry about your Inverter 'accidentally' powering your Converter, etc., as it's not wired to power it. The Inverter is NOT supplying power to the WHOLE electrical panel, but only to some dedicated breakers/circuits designed to be powered by it.

Now, when you then add Solar Power, thru it's two wire output, it simply goes to it's Charge Controller, and those two wires go to your Battery Bank.
There's no reason to 'remove' the converter. No reason to worry about the Inverter 'feeding' the Converter when it's on, or any worries whatsoever.



My own coach came with only an Inverter.. no converter needed, since the 'whole house' Inverter does the same job. When 12v devices and appliances thru the Fuse Panel use battery power, the Inverter's Integrated Battery Charger takes care of recharging the batteries, if on Shore or Generator, or even the Alternator. When off-grid, the Solar Power does the recharging. Simple.
When the Inverter is On and is providing 120v power, it ONLY serves the circuits under it's Sub-Panel wiring scheme, which is 4 - 15amp circuits for the fridge, microwave, and all outlets in the coach.
Even if my coach had a Converter, it would not be part of the sub-panel, and therefore would not receive any 120v power from the Inverter, only from Shore or Generator power, when the Inverter is then simply 'passing-thru' 120v power to it's dedicated sub-panel circuits.

The solar, no matter how small an array, or how large, is simply recharging the House battery bank. There is no 'direct' solar power to anything, other than the batteries for charging.

[Skwidward]

after reading some of your original ideas, I think that whats missing is that no Converter, on it's own breaker, is part of the equation with the Inverter's output - simply, the Inverter is only designed for 'some' circuits, not all, and not including the Converter, the Air Conditioner(s), the electric Water Heater, the engine Block Heater, or any 'large draw' appliances or devices not intended to be powered by the Inverter - the SUB PANEL for the Inverter's output takes care of only the circuit it is intended to power. Some inverters are small and only designed and wired to one or a few dedicated items, while others are 'whole house' inverters, with integrated battery Chargers, to handle the charging and the output to most, or all, outlets, in a single unit. These will have a breaker output in your Main panel to supply the 120v Shore or Gen power, and will have a sub-panel for the return power from the Inverter when it is providing power, or passing-thru Shore or Gen power.

So, that being said, you don't ever have to worry about your Inverter 'accidentally' powering your Converter, etc., as it's not wired to power it. The Inverter is NOT supplying power to the WHOLE electrical panel, but only to some dedicated breakers/circuits designed to be powered by it.

Now, when you then add Solar Power, thru it's two wire output, it simply goes to it's Charge Controller, and those two wires go to your Battery Bank.
There's no reason to 'remove' the converter. No reason to worry about the Inverter 'feeding' the Converter when it's on, or any worries whatsoever.



My own coach came with only an Inverter.. no converter needed, since the 'whole house' Inverter does the same job. When 12v devices and appliances thru the Fuse Panel use battery power, the Inverter's Integrated Battery Charger takes care of recharging the batteries, if on Shore or Generator, or even the Alternator. When off-grid, the Solar Power does the recharging. Simple.
When the Inverter is On and is providing 120v power, it ONLY serves the circuits under it's Sub-Panel wiring scheme, which is 4 - 15amp circuits for the fridge, microwave, and all outlets in the coach.
Even if my coach had a Converter, it would not be part of the sub-panel, and therefore would not receive any 120v power from the Inverter, only from Shore or Generator power, when the Inverter is then simply 'passing-thru' 120v power to it's dedicated sub-panel circuits.

The solar, no matter how small an array, or how large, is simply recharging the House battery bank. There is no 'direct' solar power to anything, other than the batteries for charging.