RV solar and generator battery charging advice requested

[tmw]

Hi People,

First, I have owned an RV before and used it for occasional family trips. I am new to solar and do not know much about how RVs are usually wired. I am capable of wiring some things like basic 120v outlets and light switches. I even wired up my Tesla charger which supports the full 48 amp 240v charging rate. That seemed easier than some light switches frankly... A bit concerned that I know just enough to get myself in trouble with my setup...

I expect to purchase a few year old ~38' class A RV in a few months and plan to live in it full time while traveling around the western half of the US for a year or two. I plan to mostly travel with the weather and try to stay in places where the high is 90 max and lows above freezing and where it cools down at night. I may also stay at places without utilities for up to a week. I expect to be running Starlink, a laptop, a 43" LED monitor, occasional AC plus misc other things that I will have a better estimate of after I actually have the RV.

I'd like to have enough battery power to support running base load and perhaps an hour or two of AC ( 2 - 15k btu units drawing about 1.5kw ) for 24 hours without needing to charge. Ideally if I am not running the AC, I'd like to be able to operate on solar and batteries indefinitely and use the generator to recharge batteries when cloudy or exceptionally hot etc. If I go somewhere I need AC all the time I plan to plug in to 50amp service.

My daily power use estimates follow:

• inverter base load: 50w/hr x 24 hrs = 1.2kW
• daytime load: 300w/hr x 16 hrs = 4.8kW
• nighttime load: 60w/h x 8 hrs = 0.48kW
• optional AC use: 3.0kw/h x 2 hrs = 6kW
• cooking, lights, pumps, and anything else: no real idea for daily load so will want extra capacity for this, plus extra battery capacity is not a bad thing

Daily total no AC: 6.48kW
Daily total w/ minimal AC: 12.48kW
Max inverter load - continuous: < ~5kW ( AC running, cooking, etc... and not for long )

I expect the RV to have an ~6kW/hr generator
I expect to install ~1800 watts of shade tolerant flexible monocrystalline solar panels on the roof with another 1200 watts of optional solar on a ground mount if I am staying somewhere a while. May consider power optimizers for shade vulnerable panels. If my 1800 watts is very shade tolerant, my guess is I can assume about 4.8kw of energy added to my batteries per day. Add the ground mount panels for another 3.6 kw totaling 8.4 kw solar power on an ideal day. Looks like enough if I d/n run AC and could run AC every few days for an hour if wanted.

Equipment Setup Thoughts

I am very interested in a reliable system that 'just works' and d/n require constant tinkering to work well. However, I would appreciate a system that is flexible enough to enable tinkering when I want to Following is my initial thoughts based a lot on Will's reviews and my hopes of keeping this as simple as possible.

1 - EG4 6000xp all in one inverter - I understand this will handle battery charging and load when plugged into 50 amp 240v service
1 - EG4 PowerPro wallmount 14.3 kWh LFP, though may add a second if I desire more storage but that is likely overkill...
1 - EG4 ChargeVerter for generator ( can fully charge batteries in ~3 hours )
1 - EG4 ChargeVerter for charging with 120v AC configured for 20 amp circuit - this will be a separate power cord from the 240v 50 amp service cord
1 - 12v LFP 100 amp hour battery to support the 12 volt systems ( running the hydraulic leveling system can require 50+ amps )
1 - 48v to 12v battery charger to keep the 12v LFP battery at 80%

General Operation Assumptions

1. The RV will run off the inverter unless I am plugged into 240v 50 amp shore power
2. I will run the generator to charge the batteries using the ChargeVerter when they run low. With some systems this can be automated based on the battery voltage and am hoping that will work for me.
3. It will be possible to charge the batteries with 120v 20 amp shore power ( most likely will limit draw to 15 amps using ChargeVerter ) but will take 9 hours or more to fully charge the batteries from empty using 120v source at 15 amps.
4. Hoping the solar will provide enough power so generator use is not needed unless due to excessive cloudy days etc.

Questions:

1. What of the above is incorrect, a bad estimate, or otherwise impractical?
2. What safety considerations are recommended for this type of setup?
3. Are my solar power estimates anywhere near realistic? How much can I increase the gain from the ground mount solar panels if I rotate them every few hours to better face the sun? Would that even be worth the bother?
4. How difficult would you expect this to be to wire up in the RV? Tough question possibly as I am looking at three different RV models... Conceptually, I would like to take the output from the 6000xp inverter and wire it to the RV 240v shore input and then wire the 240v shore input directly to the 6000xp external AC input. Is this a wise way to install the system? I wonder if the RV will be smart enough to think I am still connected to shore power and have an alarm go off when I shift the RV into drive...
5. Will I need additional transfer switches to connect to 240v shore power? I think I can route this directly to the 6000xp which will handle pulling power from shore when power is available but is this correct?
6. How would you recommend setting up monitoring? I think I would prefer a control center with the option to use my cell phone/laptop if wanted.
7. What other equipment would you recommend considering other than the EG4 setup?
8. For RV use, I really like the way the EG4 powerpro battery, for only $300 more, it is dust and water resistant and designed for external use though I plan to keep the battery in a ventilated compartment.
9. How much heat does the 6000xp output when powering 4000 watts of load? Considering where to install and what air flow etc is needed.
10. How loud is the 6000xp when powering 4000 watts of load?
11. Can the EG4 components be installed flat for easier fit in the storage areas below the RV floor?
12. Are their significantly cheaper and/or better ways of doing this?
13. Is anyone aware of a circuit diagram for the above setup or for a very similar setup?
14. What else am I missing?

Thanks for your thoughts and suggestions!
Tom

 

[HarryN]

Great start.

I would not put a high voltage solar panel array on top of an RV if possible. Anything over 80 volts is pushing it in my opinion. Others will disagree and I have no problems with that.

Out here in the west, the heat can be brutal, and the sunlight can feel like laser beams coming down from the sky. If you need air conditioning, and want to run it on batteries, then plan for 10 hrs / day, not 2 hrs / day. For an RV that size, often they have 3 air conditioners, each pulling nominal 1 kW averaged over time, so more like ( 10 hrs ) x ( 3 kW ) ~ 30 kW-hrs of power per day.

At that point, the rest of your loads are negligible.

Anything less than 15 kW-hrs of battery power, plan to run the generator every day from 12 - 7 pm in the summer when out west.

____________

As far as components, mobile use is not the same as stationary use, so don't imagine that a battery pack designed for stationary use is a good fit for mobile use.

_____________

There are a lot of EV charge stations around, so consider to design your system to take advantage of that resource if possible.

 

[tmw]

Appreciate your feedback HarryN!

 

[Badbyte]

In my opinion, your estimates are close enough, except the ac, you will find that you will be using it more then your estimate.
I have no experience with the EG4 stuff so I can't help you there.

I custom built my RV from a 19' moving box truck with overhang, no windows except the small crescent one in my door, beefed up all the walls and now have 4" of insulation in all the walls. 6" in the ceiling and floor. Approximately 140 sq foot living space.
I've lived in this RV over winter time and summertime for last 2.5 years, temps ranged from -45 degrees F to 110 degrees.
Winter time all I neede to keep it at normal temps was a 2000 watt electric heater.
Summer time, a 5000 btu (approx 500 watts) window air conditioner was just barely able to keep it comfortable, but was running constantly on the hotter days (8 to 10 KWh used in one day just by the ac).

I recently replaced my electrical system completely.
Battery: diy, 16s 280Ah LiFePo4 (14 KWh pack)
Inverter: SRNE ASP48100U200-H 10Kw split phase
Regular appartment sized appliances - fridge, freeze, induction cooktop, pc that runs all the time, 4" 34 watt led light that is on for 12-14 hours a day (gotta keep my house plants happy, lol), other minor electrical appliances, 32" led tv and xbox one, wifi setup, cell phone signal booster...you get the idea... regular house type setup.

Regular RVs only have about 1"- 2" inches of insulation all around with lots of windows... that means lots of heat gain when it's hot outside and loss when it very cold.

For normal use without ac, I can use my truck normally (no power saving methods) for almost 2 days without solar or any other power coming in. With AC being used that cuts it down to 12 hours or more (depends on how hot it is outside) before batteries are empty.

I've ordered another 2 packs worth of batteris for a total capacity of 42 KWh, since there were a few time with hardly any sun out that I ran out of power and had to use the generator more then I wanted to. I have a 7.5 Kw diesel generator permanently installed in one of my side compartments. I use a manually transfer switch to change to shore power or to the generator.

Solar power wise, with the ground mount, it should be more then enough for your basic needs. Beware of high winds blowing your ground mounted panels away. I'm considering building a solar rack that will mount to the upper sides of my RV, hinged at the top so that I can fold them out when I'm parked somewhere with lots of space around me, also would give me an awning or sorts. Connected to the inverter all the time.
Check the specs of the inverter you buy to see what the minimum and maximum MPPT voltages are that it requires to function properly, that will determine what type of panels you will need and how to wire them up to get the required voltage. Does the inverter have more then one MPPT input?... One for roof mounted solar, second one for ground mounted solar panels.

Key things to note since all this stuff is installed in an RV that will be shaken about a lot due to bad roads and such:
-vibrations and pot holes are a pain to deal with - I had my fridge tear the anchors out twice because of really bad potholes...sigh
-Secure everything more then you think you will need to and use lock washers and/or locktite everywhere, zip ties help a lot with securing wires
-using the AC IN of the inverter to connect to shore power works just fine, so long as it is split phase 240V, inverter handles it just fine
-be warned that there is no alarm to tell you that you're still plugged in when you start driving away, so if you want that feature you will need
to reverse engineer and reuse existing parts in your RV, if it came with that feature originally
-using a chargeverter or something similar to charge your pack on 120V is a must, since a lot of places either don't or can't supply 240V split
phase power, but you can find 120V 15 amp outles almost everywhere, same issue with driving away alarm.
-batteries will need to be properly strapped together and then solidly mounted to the RV so they will not come loose when you hit that large pot
hole that came out of nowhere...lol
-if you will be building your own battery pack, like me, then use flexible straps between the cells so that vibrations will not damage the posts or
batteries over time, if the inverter insallation manual says to use 1 awg cables, use 1/0 instead, bigger is better for DC battery systems.
-some inverters can be installed in any position and since you plan on installing yours in the storeage compartments - make sure the inverter you select will physically fit in the orientation it requires in the space you have and that there is plenty of ventilation to keep it cool
-use proper fuses and breakers on everything!! can not stress this enough - requirements will vary depending on application

Hope that this helps a little. In the end, it will depend a lot on the RV you buy, available space, available time to do the work and how much money you have to spend on this project.

 

[tmw]

In my opinion, your estimates are close enough, except the ac, you will find that you will be using it more then your estimate.
I have no experience with the EG4 stuff so I can't help you there.

I custom built my RV from a 19' moving box truck with overhang, no windows except the small crescent one in my door, beefed up all the walls and now have 4" of insulation in all the walls. 6" in the ceiling and floor. Approximately 140 sq foot living space.
I've lived in this RV over winter time and summertime for last 2.5 years, temps ranged from -45 degrees F to 110 degrees.
Winter time all I neede to keep it at normal temps was a 2000 watt electric heater.
Summer time, a 5000 btu (approx 500 watts) window air conditioner was just barely able to keep it comfortable, but was running constantly on the hotter days (8 to 10 KWh used in one day just by the ac).

I recently replaced my electrical system completely.
Battery: diy, 16s 280Ah LiFePo4 (14 KWh pack)
Inverter: SRNE ASP48100U200-H 10Kw split phase
Regular appartment sized appliances - fridge, freeze, induction cooktop, pc that runs all the time, 4" 34 watt led light that is on for 12-14 hours a day (gotta keep my house plants happy, lol), other minor electrical appliances, 32" led tv and xbox one, wifi setup, cell phone signal booster...you get the idea... regular house type setup.

Regular RVs only have about 1"- 2" inches of insulation all around with lots of windows... that means lots of heat gain when it's hot outside and loss when it very cold.

For normal use without ac, I can use my truck normally (no power saving methods) for almost 2 days without solar or any other power coming in. With AC being used that cuts it down to 12 hours or more (depends on how hot it is outside) before batteries are empty.

I've ordered another 2 packs worth of batteris for a total capacity of 42 KWh, since there were a few time with hardly any sun out that I ran out of power and had to use the generator more then I wanted to. I have a 7.5 Kw diesel generator permanently installed in one of my side compartments. I use a manually transfer switch to change to shore power or to the generator.

Solar power wise, with the ground mount, it should be more then enough for your basic needs. Beware of high winds blowing your ground mounted panels away. I'm considering building a solar rack that will mount to the upper sides of my RV, hinged at the top so that I can fold them out when I'm parked somewhere with lots of space around me, also would give me an awning or sorts. Connected to the inverter all the time.
Check the specs of the inverter you buy to see what the minimum and maximum MPPT voltages are that it requires to function properly, that will determine what type of panels you will need and how to wire them up to get the required voltage. Does the inverter have more then one MPPT input?... One for roof mounted solar, second one for ground mounted solar panels.

Key things to note since all this stuff is installed in an RV that will be shaken about a lot due to bad roads and such:
-vibrations and pot holes are a pain to deal with - I had my fridge tear the anchors out twice because of really bad potholes...sigh
-Secure everything more then you think you will need to and use lock washers and/or locktite everywhere, zip ties help a lot with securing wires
-using the AC IN of the inverter to connect to shore power works just fine, so long as it is split phase 240V, inverter handles it just fine
-be warned that there is no alarm to tell you that you're still plugged in when you start driving away, so if you want that feature you will need
to reverse engineer and reuse existing parts in your RV, if it came with that feature originally
-using a chargeverter or something similar to charge your pack on 120V is a must, since a lot of places either don't or can't supply 240V split
phase power, but you can find 120V 15 amp outles almost everywhere, same issue with driving away alarm.
-batteries will need to be properly strapped together and then solidly mounted to the RV so they will not come loose when you hit that large pot
hole that came out of nowhere...lol
-if you will be building your own battery pack, like me, then use flexible straps between the cells so that vibrations will not damage the posts or
batteries over time, if the inverter insallation manual says to use 1 awg cables, use 1/0 instead, bigger is better for DC battery systems.
-some inverters can be installed in any position and since you plan on installing yours in the storeage compartments - make sure the inverter you select will physically fit in the orientation it requires in the space you have and that there is plenty of ventilation to keep it cool
-use proper fuses and breakers on everything!! can not stress this enough - requirements will vary depending on application

Hope that this helps a little. In the end, it will depend a lot on the RV you buy, available space, available time to do the work and how much money you have to spend on this project.

Wow Badbyte - thanks for all the advice! I look forward to putting it to use! Tom

 

[Dallas from Minnesota]

Badbyte, that's a lot of awesome advice in one post. I've been in my Ram 3500 for about 6 months now, and I couldn't agree more about strapping everything down. I'm in OK, where the roads are made of potholes, and the right turn lanes are considered offroad. I learned that lesson quickly! Wondering where you put in a window AC in your setup? I thought about cutting a hole above my back doors (extended ceiling).

Regarding
" considering building a solar rack that will mount to the upper sides of my RV, hinged at the top so that I can fold them out when I'm parked somewhere with lots of space around me, also would give me an awning or sorts. Connected to the inverter all the time"

Awedome idea! I have an old hi-lo camper turned onto a mobile retail shop, and I use 2 jackery portable folding panels as awnings above the windows on one side, DIY awning on the storefront side. I clip them onto washers that slide along the awning rail, and take them down when I'm traveling or there is a storm. They charge my small portable jackery power station. My intro to solar power, which is enough for the camper/store but not the van unfortunately.

 

[jberger]

Pick an RV with the right floorplan first, then start choosing the equipment. A bad floorplan will drive you crazy, the right floorplan will make it feel like home.

Your choice of RV is going to have a big impact on the equipment selection, you can't just throw something like the PowerPro battery into just any location, it's too heavy. Skip the flexible panel plan for the roof, they won't last and the power output will be lower.

I'd suggest looking at Victron, not EG4 for this type of application. The EG4 gear is going to run Hot and Loud and isn't really designed to be stuffed in a bay or closet.

You mention cooling but heating is just as important, so look for a unit that has diesel based hydronic heating, this can make a big difference in domestic hot water and overall comfort, it's also much easier on your battery bank.

If you get a chance to buy one or upgrade one to a residential fridge, do it. I can't explain how much we appreciate having a full size, residential fridge.

Replacing the average propane cooktop with an induction setup is a nice upgrade too, my wife loves it and we have a couple of hobs we can use outside when the weather is nice too.

You don't really need 1 or 2 chargeverters, you can let the inverter charge the batteries from shore/genset. Most class A units will already have an automatic transfer switch (ATS) in place and the inverter will set behind that ATS. If you understand how the ATS works, you will see that you won't need 2 chargeverters in either case, as the incoming power will get switched (Shore/Genset) to the inverter. If you wanted additional charge capabilities, you could add another charger after the ATS.

Depending on the chassis, you might already have space allocated for a large house bank of 4d/6d/8d batteries, so you can just reuse that space with LFP batteries. You might need to work out a warming plan for freezing weather, but it they could drop in with little to no issues. It's MUCH easier to drop those in and deal with than trying wrestle with a 300+ lb powerpro.

With regard to your power consumption calculations, I think you are well below what you will actually be using, especially overnight, so leave yourself with plenty of slack in that regard. I mention overnight because if you are in a spot with quiet hours, it's that power use overnight that can become your limiting factor.

 

[mmmmmdonuts]

I posted about my build in a thread here: RV build

It looks similar to what you're looking for and I am using most of the equipment you have listed. I have a 38' tow behind trailer just as an FYI.