Will this plan work?

[Scar]

So I'm a disabled army vet and plan on hitting the road. I bought a 31 foot Winnebago class C and I'm looking to set up solar sufficient to mostly run everything as I start traveling, especially as I have two large dogs that I want to be able to leave in air conditioning when I leave for the day.

1: Solar panels: I'm thinking of going with four of these 455W panels from Santan Solar. My roof has two large open areas, one being 100 inches square, and the other being 100x85 inches. These seem to be the best way to get the most power out of those areas. I am expecting to wire all my panels in series. I am wondering if it is possible to mix 4-6 of Santan's 100w panels into the mix as well somehow, though I suspect it may not be advisable.

New SolarEver 455W 144-Half Cell Mono Solar Panel

New Solarever 455W are in! They are great for your solar grid application system. Get yours today by clicking on the link!

store.santansolar.com

New SanTan 100W Solar Panel | SanTan Solar

store.santansolar.com

2: MPPT/Inverter/Charger I'm planning on going with an EG4 6.5KW all in one. My concern here is I have no earthly idea where to put it. One entire wall of my rig is a slide aside from the rear bedroom, and the other is all kitchen aside from the shower and bedroom. and I understand the fans can be intrusive. I have a very large 84 cubic foot rear storage bay, but I expect temperature could be an issue. Would it be better to not meet clearance specifications and mount it in a kitchen cabinet with a couple of vent fans cycling air from inside the trailer through the cabinets?

EG4 6000XP Off-Grid Inverter | 8000W PV Input | 6000W Output | 480V VOC Input | 48V 120/240V Split Phase | All-In-One Solar Inverter (Pre-Order)

The EG4 6000XP is a cutting-edge 48V split-phase, off-grid inverter and charger, designed to revolutionize your energy needs. With an impressive 8kW of PV input capacity and an efficient 6kW continuous power output, it also serves as a battery 140A charger. What sets it apart is its scalability...

signaturesolar.com

3: Batteries, I'm planning on two 48v EG4 batteries, still undecided as to whether or not to spring for the one with the longer warranty, but the fact it's prorated makes it seem somewhat pointless. These will be mounted in the rear storage bay, I'll add a layer of insulation underneath, but I don't really expect to spend much time in freezing temperatures and they have temperature cutoffs.

EG4 LifePower4 Lithium Battery | 48V 100AH | Server Rack Battery | UL1973, UL9540A | 5-Year Warranty (Pre-Order)

EG4 (48V/100AH) LifePower4 Battery EG4 Lithium battery 51.2V (48V) 5.12kWh with 100AH internal BMS. Made of UL Listed Battery Cells. Off Grid Solar Batteries - Off Grid System - Solar Batteries for Home - Lithium Solar Batteries - Deep Cycle Solar Batteries - Power Reserve - Solar Panels Plus...

signaturesolar.com

Beyond those parts I'll mostly be following will's guidance with some modifications to fit my system requirements:

200 amp T-class fuse

2 AWG copper wiring between the batteries and the inverter(my RV is on a 30 amp connection and set up as such so at 48v I shouldn't exceed 75 amps).

PV isolator switch: https://signaturesolar.com/dc-disconnect-rooftop-isolator-switch-by-imo/?ref=cPwLcVc0SW-BjN

And of course the slew of odds and ends from there. If I'm not very much mistaken I simply wire my 30 amp connection as the AC input on the all in one and wire the all in one to the existing breaker box. I've got an Onan 4k generator for when the solar can't top up the batteries.

Thanks for reading, and in advance for any advice you may provide!

Edit- Almost forgot, does anyone have any advice on a buck converter sufficient to operate a slide out? I was thinking of using this.

36V 48V to 12V 100A 1200W DC DC Step Down Converter Voltage Regulator w/ACC

Wide input voltage from 30 to 60V Work for appliances from 0AMP to 100AMP automatically 100% full rated power 100% full stable output current 100% burn-in test High-efficiency up to 95% Waterproof sealed Cooling by free air convection Surface mountable 3-year warranty Over-current, over-voltage...

daygreen.com

 

[sunshine_eggo]

1: When you parallel panels in an array, their Vmp-Voc values need to be very similar. When you series panels, they will operate at the lowest current panel in the string. Series is out based on the disparity of the currents, and with parallel you'd need 4.5 100W panels to match with the big panels. Not good. The best bet is to get a second charge controller dedicated to the 100W panels.

2: In addition to space, that's a VERY large inverter for your array, and likely not appropriate for your rig. With a 30A plug, you may not have sufficient wire rating. It also has a high idle draw and will consume about 25% of your battery bank just by being on. ONE of your 455W panels will be dedicated to replacing that energy, i.e., you will eat 25% of your battery capacity, which requires the full day exposure of on of the big panels to replenish it daily - this is just by having it turned on and using no loads.

3: okay.

Personally, for the sake of simplicity and "backup," I would retain the existing 12V and converter and simply power it with the AC output of the inverter. This way, if you have to take the system offline, you will always have 12V power, and with a battery in the circuit, you don't have to worry about excessive loads.

 

[Scar]

1: That's more or less what I thought on the 100 watt panels but I wasn't really sure if it was even ok to just attach another mppt of a different kind to these batteries at the same time. Easy enough, I'll just add a separate mppt for however many small panels I can squeeze up there.

2: I get that it's more than needed, but a 3k is going to struggle to run much more than the air conditioner, for instance if I wanted to run the microwave, plus the 3k has almost the same idle consumption based on Will's testing. I'm also unsure how tying a 6.5k KW inverter in differs from using a 50-30 dogbone adapter, I'll still be retaining the same 30 amp breaker between the inverter and the AC wiring. If you have any recommendations that would work significantly better at a similar price point or lower I am absolutely all ears though.

As far as retaining the current 12v system I am kind of counting on ditching it for the weight savings to offset some of the weight I'll be adding. As with most class c's I'm not exactly flush with spare payload capacity.

Thank you!

I'm gonna go map out exactly how many of those 100 watt panels I can squeeze in and still be able to walk on the roof if needed and figure out which mppt is the right size for what I can fit.

 

[sunshine_eggo]

1: That's more or less what I thought on the 100 watt panels but I wasn't really sure if it was even ok to just attach another mppt of a different kind to these batteries at the same time. Easy enough, I'll just add a separate mppt for however many small panels I can squeeze up there.

You'll want at least 4 of them in series to ensure adequate voltage for charging.

2: I get that it's more than needed, but a 3k is going to struggle to run much more than the air conditioner, for instance if I wanted to run the microwave, plus the 3k has almost the same idle consumption based on Will's testing. I'm also unsure how tying a 6.5k KW inverter in differs from using a 50-30 dogbone adapter, I'll still be retaining the same 30 amp breaker between the inverter and the AC wiring. If you have any recommendations that would work significantly better at a similar price point or lower I am absolutely all ears though.

A/C is typically 1200-1400W. 1000W microwave is about 1600W.

3000W are about 45W, so the 6500 is pretty close to 2X that.

50-30A dogbone isn't relevant. A 30A power source can only supply 30A. Inverter can supply > 50A to your panel. You're leaving the 30A input breaker, so you're hobbling a 6500W inverter to 3600W... basically paying for nearly 2X the capacity you can never use unless you create another circuit.

"similar price point" - you're priced for cheap chinese stuff. Your only option is cheap Chinese stuff if that's your price point. If bulletproof reliability and some measure of efficiency is important to you, you might want to reconsider.

Make sure you add $650 in unusable battery capacity and the entire cost of one of your 455W panels goes to the price of that inverter since you're actually paying to feed that inverter's hungry power needs.

As far as retaining the current 12v system I am kind of counting on ditching it for the weight savings to offset some of the weight I'll be adding. As with most class c's I'm not exactly flush with spare payload capacity.

IMHO, after they leave the lot, no RV on the planet is under GVWR. Assuming 40gal tanks, you'll have 1000# of "fluids" if they're full. IMHO, redundancy is typically worth its weight.

Consider:

Victron MultiPlus-II inverter & charger 3000 Watts, 48 Volts DC, 120 Volts AC, 35 Amp Charger

Part Number: PMP482305100 Note: To do advanced Inverter configuration and setup you must have a VE.Bus To USB MK3-USB Interface.

www.solar-electric.com

6000W legit surge capacity. Burns a measly 13W - that's 3% of your battery capacity.

You'll need a 20A MPPT on top of that, but Victron's smallest at 150V is 35A:

Victron Energy SmartSolar MPPT 150/35 Solar Charge Controller up to 48VDC at 35 Amps

Part Number: SCC115035210

www.solar-electric.com

BUT any 150V/20A+ MPPT will work if you want cheaper than Victron.

Smart shunt:

Victron Energy SmartShunt 500A/50mV Battery Shunt

Victron Energy SmartShunt 500A/50mV Smart Battery Shunt is an all in one battery monitor, only without a display.

www.solar-electric.com

Cerbo:

Victron Energy Cerbo GX Panels and System Monitoring

Part Number: BPP900450100

www.solar-electric.com

Smartshunt and Cerbo are for max "pimpin'" on the system.

Here's a price breakdown:

Inverter	Price	Consumed battery	Consumed Solar	MPPT	SS	Cerbo	Total "Cost"	usable bat cap, kWh	$/cap	Usable PV, kWh	$/PV
EG4	$1,249	$650	286				$2,185	7840	$159	2.15	$581
MP-II	$1,388	$88	$39	$323	130.9	$341	$2,310	9928	$220	4.24	$515

Note that the Total "Cost" is illustrative. It is not used in the $/cap and $/PV numbers. Actual cost ($1249 for EG4 and $2183 for Victron) is used.

$/cap is $/usable battery cap in kWh - Victron costs 44% more.
$/PV is $/usable PV production in kWh - EG4 costs 13% more.

Yes, Victron stuff will be more expensive, but you'll have 20% more usable battery capacity and nearly 2X the DAILY power consumption available from PV.

People get hung up on the low prices of these inverters, but they rarely pay attention to the cost to the overall system. Your limited PV space means that you are limited to your daily PV harvest for consumption. With EG4, you can only sustainably use 2.15kWh/day, but with Victron, you can use 4.24kWh per day.

Also, running A/C on the proposed system is a dream. With EG4, you might be able to run it for 1.5 hours/day. Maybe 3 hours on Victron. More than that, and you're gobbling up battery capacity daily until they eventually run out of juice, and you have to charge with gen.

Installing an inverter that consumes 50% of your daily PV is firmly in the "not a good choice" spot.

 

[Scar]

Fair enough on the Victron, I think I'll skip the cerbo though(I'll research it more then decide). I was up on my roof and honestly even adding the 100 watt panels seems rather pointless as most of the open spots will have some amount of shade at any given time so unless I were to wire them up on separate mppt chargers they'll be hobbled except for maybe 3 hours a day. This makes it more important that I get the most out of my 4 large panels and not waste power as you said. For the suggested MPPT should I wire the panels in a 2s2p configuration?

Actually as far as my GVWR is concerned I'm rolling around at about 1k pounds under right now fully loaded with a full tank of gas and including occupants, but I want to be able to tow a small trailer for a couple motorcycles, which shouldn't add much to the tongue weight.

And as far as the AC is concerned my plan is for it to be able to run during peak heat about 4-5 hours/day hopefully offsetting most of the consumption with solar, and have the solar panels top up whatever has been used in the afternoon and morning, I'm not really looking to be able to run it overnight off the solar.

Thanks again!

Edit- Ok, I just watched Will's video on the victron setup, I'm seeing the importance of the cerbo.

 

[sunshine_eggo]

Fair enough on the Victron, I think I'll skip the cerbo though(I'll research it more then decide). I was up on my roof and honestly even adding the 100 watt panels seems rather pointless as most of the open spots will have some amount of shade at any given time so unless I were to wire them up on separate mppt chargers they'll be hobbled except for maybe 3 hours a day. This makes it more important that I get the most out of my 4 large panels and not waste power as you said. For the suggested MPPT should I wire the panels in a 2s2p configuration?

Crap... not sure what I was thinking. I had it in my head that you only had space for 2 - reading fail. That changes the numbers.

Inverter	Price	Consumed battery	Consumed Solar	MPPT	SS	Cerbo	Total "Cost"	usable bat cap, kWh	$/cap	Usable PV, kWh	$/PV
EG4	$1,249	$650	286				$2,185	7.8	$159	6.7	$186
MP-II	$1,388	$88	$39	$323	130.9	$341	$2,310	9.9	$220	8.8	$248

Victron is more all around since you'll be able to use 3 of the panels with EG4 vs. just 1.

Yes, 2S2P on the big panels.

Cerbo will allow EG4 battery communication with Victron system if that matters.

Actually as far as my GVWR is concerned I'm rolling around at about 1k pounds under right now fully loaded with a full tank of gas and including occupants, but I want to be able to tow a small trailer for a couple motorcycles, which shouldn't add much to the tongue weight.

Impressive.

And as far as the AC is concerned my plan is for it to be able to run during peak heat about 4-5 hours/day hopefully offsetting most of the consumption with solar, and have the solar panels top up whatever has been used in the afternoon and morning, I'm not really looking to be able to run it overnight off the solar.

PV total energy delivered:

EG4: 6.7kWh / 1.3kW*.85 = 4.4 hr of A/C
Victron: 8.8kWh / 1.3kW*.85 = 5.8 hr of A/C

.85 is an efficiency factor in inverting DC to AC and other system losses.

Any other consumption would take away from those, it does not consider effects of shading, and it assumes you're getting 5h of solar insolation/day.

Consider supplementing with ground arrays constructed with flexible 100W panels and PVC frames. 4S of those in parallel would be fairly compatible with your 2S2P roof array.

If you have a propane fridge, run it off propane. A modest 7.6 cu-ft unit consumes 4-5kWh of AC energy per day.

 

[Scar]

Yeah, aside from the air conditioner our electricity consumption will be modest, using a propane fridge/stove/water heater. I'll probably use a small electric heater in the winter to the extent solar allows but there is a propane furnace that will be used as necessary. It appears the Multiplus-II you pointed me towards also has a generator auto start function so I'll wire that up to kick on at around 50% SOC. You scared me a bit saying only a couple hours of air conditioning off this system, I thought I somehow forgot how to do any math at all. Seeing as my biggest factor is space available you're 100% right about going with the Victron unit, I can't afford to piss away an entire solar panel.

Thank you!

 

[sunshine_eggo]

Yeah, aside from the air conditioner our electricity consumption will be modest, using a propane fridge/stove/water heater. I'll probably use a small electric heater in the winter to the extent solar allows but there is a propane furnace that will be used as necessary. It appears the Multiplus-II you pointed me towards also has a generator auto start function so I'll wire that up to kick on at around 50% SOC. You scared me a bit saying only a couple hours of air conditioning off this system, I thought I somehow forgot how to do any math at all. Seeing as my biggest factor is space available you're 100% right about going with the Victron unit, I can't afford to piss away an entire solar panel.

Thank you!

Electric heat is a bugger (better to run your A/C if it also works as a heat pump), but if you have the surplus, if you don't use it, you'll lose it!

Generator auto-start may differ from what the RV generator needs. You'd need to do your homework on that one as I barely have a grasp on the concept. Generally speaking for stationary power systems where generator auto-start is a feature, there's something of a "standard" where they equipment behaves a certain way to make it work. I expect you can likely rig it to auto-start, but you many need to stop it manually.

 

[Scar]

Electric heat is a bugger (better to run your A/C if it also works as a heat pump), but if you have the surplus, if you don't use it, you'll lose it!

Generator auto-start may differ from what the RV generator needs. You'd need to do your homework on that one as I barely have a grasp on the concept. Generally speaking for stationary power systems where generator auto-start is a feature, there's something of a "standard" where they equipment behaves a certain way to make it work. I expect you can likely rig it to auto-start, but you many need to stop it manually.

Yep, I wish it had a heat function, if this AC ever dies on me I'll swap to a mini split with heat and add another set of panels. I'll see what it'll take to auto start, it's an Onan 4k so I'm certain it's possible as common as these generators are.