I am looking to install 300 watts of solar, mppt controller, 3 100ah AGM batteries, and a 2000 watt pure sine wave inverter in my '92 Cobra American. The rig currently has an Onan Emerald 1 genset, a miniscule house battery under the hood and a shore power/generator/house battery transfer switch. My question is how, or can I tie the new solar into the existing system? I would like to be able to use the existing 12v/110v outlets. Thanks, Rick
Tying solar to existing 12v/120 wiring
- Thread starter Trainrick
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You don't want more than one House bank, made up of identical batteries purchased at the same time, ideally all located together.
True deep-cycle batt selection discussion another time.
Your House bank can be tied to the alt-Starter batt circuit through a solenoid/relay if it isn't already. Or an ACR if you want charging to be two-way from any source.
But ideally all charge sources including alt and SC should go directly to House where high currents are needed.
then an Echo Charger can keep Starter topped up, really minimal amps needed in that direction.
All this is "infrastructure" wiring, supply to load consumers and user outlets should not need changing.
True deep-cycle batt selection discussion another time.
Your House bank can be tied to the alt-Starter batt circuit through a solenoid/relay if it isn't already. Or an ACR if you want charging to be two-way from any source.
But ideally all charge sources including alt and SC should go directly to House where high currents are needed.
then an Echo Charger can keep Starter topped up, really minimal amps needed in that direction.
All this is "infrastructure" wiring, supply to load consumers and user outlets should not need changing.
DLTooley
Well-known member
Presumably you'll be replacing the house battery, AGM's may not be the best way to go. Tying into the alternator circuit has a benefit, but it may be overrated. Charging your house battery from solar is straight forward. The questions I'm still trying to answer myself is how different charging systems interact.
The simplest answer is not to let them interact. That's not the best answer, but it should be the cheapest. My thought would be that running the generator for a short time in conjunction with early solar would be without problems and a benefit.
Keeping track of your actual charge and load is important. The smaller Victron MPPT does that effectively up to a 12v 15amp load for the Solar only. To maximize everything tied together will probably require a battery management system and more. If you don't find a better answer I'd at least consult a professional.
The simplest answer is not to let them interact. That's not the best answer, but it should be the cheapest. My thought would be that running the generator for a short time in conjunction with early solar would be without problems and a benefit.
Keeping track of your actual charge and load is important. The smaller Victron MPPT does that effectively up to a 12v 15amp load for the Solar only. To maximize everything tied together will probably require a battery management system and more. If you don't find a better answer I'd at least consult a professional.
If you are willing to spend some money, fabricate a bit, and do some hard-wiring, you can replace the existing RV power converter with what is called an inverter-charger. Some will have a built-in transfer switch to handle both the genset and shorepower when hooked up. This will provide AC to all of the coach 120v outlets from shore hookup, genset, and solar.
You will still need a separate solar charge controller.
Again, these are not cheap, but here is an example:
https://www.amazon.com/dp/B00G6LROW4/ref=psdc_583328_t1_B01AD2MJSK
You will still need a separate solar charge controller.
Again, these are not cheap, but here is an example:
https://www.amazon.com/dp/B00G6LROW4/ref=psdc_583328_t1_B01AD2MJSK
DLTooley
Well-known member
If everything is working right the only issue will be going into float from the solar source early and you'll lose that power. I'm not expert enough to list all the scenarios where something could go wrong. Overcharging a starter battery would be one if the circuit control fails.John61CT said:
You are saying an inverter/charger in this system can handle both a generator and shore power?
Putting an ammeter on each charge circuit as well as load would be a good idea. I think the Bayite's on Amazon run around $20 per. I had issues with my shuntless model, probably due a disconnected battery wire.
You cannot have the inverter and any other 120 volt source connected together. You must deal with transfer switches. You could have separate outlets for the inverter. 2000W is not going to operate your whole 120V system.
Yes, ideally they will have similar setpoints, but in reality no significant harm, as you say each source drops out (goes to float) as its profile dictates.DLTooley said:
I prefer using only fully adjustable sources so premature infloatulation doesn't happen with any of them, but most don't go to that level of trouble and expense.
> Overcharging a starter battery would be one if the circuit control fails.
Yes, any one device can still fail in a mode that causes damage, just as it would do if it were the only one running.
But 99% of alternators never drop to Float anyway, Starters are very robust, and cheap anyway.
Everything in your design should be focused on caring for House.
Assuming your rig has a 120v plug for plugging in at campgrounds etc.
The older RV converters are very simple in their wiring, just make a switch to disconnect the 12v charging circuit (or use breaker if yours has one). With the 12v inverter charging disconnected you can just plug the outside 120v plug into your 2000 watt inverter and this will power all the wall plugs. Be sure to have rv fridge set to propane, it pulls a lot of power.
The older RV converters are very simple in their wiring, just make a switch to disconnect the 12v charging circuit (or use breaker if yours has one). With the 12v inverter charging disconnected you can just plug the outside 120v plug into your 2000 watt inverter and this will power all the wall plugs. Be sure to have rv fridge set to propane, it pulls a lot of power.
Thanks to all for your input on this subject. I don't intend to run anything other than my laptop, phone charger, TV, water pump and lights off of the solar. Sounds as though my best course of action at present would be to tie just the 12V side and leave the 110 side as it is with an independent power strip coming from the solar inverter. I would also like to be able to run my microwave for short periods of time off of the solar so I think I will run a dedicated line from the solar inverter to the microwave. Sound like it will work? Am I talking out my ass? Let me know, thanks, Rick
There is no such thing as a solar inverter, one's got nothing to do with the other.
All you are doing is charging the batteries with your solar controller, nothing needs to "change" in your existing wiring when you add another charge source.
Your inverter is just another load device as far as the 12V supply is concerned.
Your handling of the AC output from the inverter does keep thing simple.
Make sure to read the installation docs for both units, follow their recommendations wrt fusing especially.
Both devices should be close to if not right at your House battery bank.
All you are doing is charging the batteries with your solar controller, nothing needs to "change" in your existing wiring when you add another charge source.
Your inverter is just another load device as far as the 12V supply is concerned.
Your handling of the AC output from the inverter does keep thing simple.
Make sure to read the installation docs for both units, follow their recommendations wrt fusing especially.
Both devices should be close to if not right at your House battery bank.
DLTooley
Well-known member
Chargers have different methodologies for determining charge states, and that will be a factor. I believe the Victron MPPT uses the amperage acceptance rate, so that is likely good. I would hope it is as simple as you state, but I'm not sure.John61CT said:
DLTooley
Well-known member
Charging a laptop is a relatively large charge, though with 300ah of battery that's less of an issue. Still, if you can wait until after the peak initial solar charging period you'll see a benefit.
An inverter as you are thinking isn't specific to solar, it's a 12v device. Generally these should not be attached to the load terminal of your solar charger, but directly to the battery. If you have existing 120v circuitry connecting the inverter circuit to that should be doable. The thing to inspect, and watch, is the existing connection between the 120v and the 12v circuits. Fusing is crucial, and putting ammeters on circuits will help to see more detail as to what is going on.
RV Power is not simple, but it is a good project. You are certainly asking the right questions.
An inverter as you are thinking isn't specific to solar, it's a 12v device. Generally these should not be attached to the load terminal of your solar charger, but directly to the battery. If you have existing 120v circuitry connecting the inverter circuit to that should be doable. The thing to inspect, and watch, is the existing connection between the 120v and the 12v circuits. Fusing is crucial, and putting ammeters on circuits will help to see more detail as to what is going on.
RV Power is not simple, but it is a good project. You are certainly asking the right questions.
Here is how I envision the wiring being laid out. Lets see if I'm getting this straight:
Solar panel output to MPPT controller input
MPPT controller output to battery bank
Battery bank out to 2000w pure sine wave inverter
Battery bank out to 12V terminals for house battery on existing transfer switch
Switches, fuses, disconnects, shunts as required where required
Oversimplified, yes, but anywhere near close to being correct?
Solar panel output to MPPT controller input
MPPT controller output to battery bank
Battery bank out to 2000w pure sine wave inverter
Battery bank out to 12V terminals for house battery on existing transfer switch
Switches, fuses, disconnects, shunts as required where required
Oversimplified, yes, but anywhere near close to being correct?
It's just an inverter.
Your battery bank is AKA the House bank (as opposed to the Starter for cranking the engine.
Terminals is a very generic term for all kinds of fittings that help connect wiring together.
A "transfer switch" is usually involved with **AC** current, shore vs gennie vs inverter output.
12VDC House bank output (besides input to inverter) feeds your DC devices, lighting, fans, stereo, screen gadgets, fridge, whatever you may have that is designed to run off DC.
Those load consumers run consistently whether or not a charge source (solar, alternator, AC charger AKA converter) is active.
When there is no charging you should be careful not to let your bank get too depleted, tge normal standard being 50% for battery longevity.
Hope that helps.
That's not clear to me.Trainrick said:
Your battery bank is AKA the House bank (as opposed to the Starter for cranking the engine.
Terminals is a very generic term for all kinds of fittings that help connect wiring together.
A "transfer switch" is usually involved with **AC** current, shore vs gennie vs inverter output.
12VDC House bank output (besides input to inverter) feeds your DC devices, lighting, fans, stereo, screen gadgets, fridge, whatever you may have that is designed to run off DC.
Those load consumers run consistently whether or not a charge source (solar, alternator, AC charger AKA converter) is active.
When there is no charging you should be careful not to let your bank get too depleted, tge normal standard being 50% for battery longevity.
Hope that helps.
Mrcap
Well-known member
Trainrick said:
Hi Rick, I have almost an Identical setup. House generator, orphan house battery under hood, house charger. I have 500w on the roof and 300ah agms. I have all my systems tied together and have my house 12v outlets and a 110 circuit that is on 24/7. I was much easier than I thought to connect together. Please feel free to pm me if I can be of help.
John, the reason it wasn't clear to you is because I was incorrect in my assumption that the house battery would be charged through the transfer switch by the genset when running and therefore be a point to tie in to the 12v system. That does not appear to be the case, the 12v side is independent entirely of the 110v side.
Well, the points they join areTrainrick said:
Inverter goes from 12V to 110AC
Charger goes from 110 to 12V DC. Sometimes AKA a converter in RV-USA speak.
Transfer switch is on AC side only, affects which source is active, shore power or gennie.
Your plan for the inverter power helps keep that simple, only plug in what you want when off grid.
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