Journey with Confidence RV GPS App RV Trip Planner RV LIFE Campground Reviews RV Maintenance Take a Speed Test Free 7 Day Trial ×


Reply
 
Thread Tools Display Modes
 
Old 04-19-2023, 06:05 PM   #1
New Member
 
Join Date: Apr 2023
Posts: 1
Need advice on Solar setup

My husband and I are very new to the Skoolie world and I have become very lost in trying to find the right size batteries, inverter, etc. here is a rough diagram on how Iíve best determined my setup. It would be awesome if someone could tell me how badly Iím off.
Giving a lot of wiggle room, Iím thinking we need about 916ah which I was going to achieve using 6 415w solar panels and 3 400ah 12v batteries. (Should I use 24v?)

With that, Iím thinking I need a 10kw psw inverter and a 250a/12v mppt charge controller and a combiner box with a 1000a circuit breaker.

Iím still unsure about wire gauges and fuse sizes. This really seemed like more than I initially thought we needed, but thatís how it calculated when looking up appliance wattage. Any advice helps.
Attached Thumbnails
CDD2552D-018C-411C-AAF7-F1C2C2274FFE.jpg   4FEC936A-178C-4794-B737-DDFDECCC07BF.jpg  

EMC89 is offline   Reply With Quote
Old 04-20-2023, 09:59 AM   #2
Mini-Skoolie
 
Join Date: Sep 2021
Location: southern Illinois
Posts: 27
Year: 2008
Coachwork: Bluebird
Chassis: Blue Bird Vision
Engine: 6.7 Cummins
Rated Cap: 72
I am a banjo player not an electrician...

24 volt battery is better for bigger systems because the amount of amps needed to produce the same watts is double with 12 volts, thus bigger wire sizes and fuses/breakers. See Ohm's Law (volts X amps=watts). Mr. Ross Taylor was just explaining this in another post recently.
I think it helps to look at battery capacity in watts instead of amp hours, because amps without volts only tell part of the story.
DIY Solar Power Forum is full of good information.
Wire size is based on total amps being drawn and the fuse is sized to protect the wire.
Banjo Joe is offline   Reply With Quote
Old 04-20-2023, 10:41 AM   #3
Bus Crazy
 
Join Date: Apr 2020
Location: Northern California (Sacramento)
Posts: 1,453
Year: 1999
Coachwork: El Dorado Fiberglass
Chassis: Ford E450
Engine: V10 Gas
Fantastic start.

What size bus do you have?

And have you investigated Lithium Ion batteries? Much better for heavy duty systems, and for many other reasons.

I didn't do any math but at a quick glance this is a 'large' system, and if you have plenty to invest, that's great; but expect to see some significant dollar signs. For bigger systems, all of the components are bigger including wiring, breakers, labor or effort to install. You also will want to have someone with expertise work with you ultimately-this forum is fine if you are quite capable of DIY, but for electrical of this size, consider a professional opinion.

The mini split looks like it is powered by 12 volts? Maybe you meant to make it a 120 volt system and put it on the inverter...

And 10K inverter is monstrous.

Is there a reason you are going all electric? Thoughts on propane and/or a generator to reduce the size and cost of that huge system?
Rucker is offline   Reply With Quote
Old 04-23-2023, 03:01 PM   #4
Mini-Skoolie
 
Join Date: Jul 2021
Posts: 51
Initial thoughts

Sounds like a great project!

The inverter sounds big for your needs. It only needs to cover the watts of all the stuff turned on at the same time. Your wattage column adds up to about 3,600 watts so a 4,000 watt inverter may be fine. However, depending on how careful you want to be and cost constraints, you might go smaller. For example, if you don't run the cooktop and the water heater at the same time, your max total is about 2,160 so a 2,500 or 3,000 watt inverter might even work.

Your list of needs might grow a bit too: laptops? outside lights? Hair Drier? Immersion blender? Some of those items are high watts but short and selectable timed use, so would not need a bigger inverter.

Many fridges only need to run the compressor about 1/3 of the time, so 8 hours is a reasonable daily estimate which lowers the total need a bit.

Solar charge controller prices go up with the output amps. This is one area of cost savings when switching from 12V to 24V (or even 48V). For your 6 panels at 415watts each, poring all that energy (6 x 415 = 2,490W) into a 12volt battery bank needs about 200A (12V x 200A = 2,400W) but just about 100A into a 24 volt system. I am only aware of 100A SCC max by victron, Aims and EPever ranging $400-$900 each. Would need 2 of them for a 12V system.
Lots of other thoughts regarding 12V vs 24V on the forum

Your breaker for the solar panel wiring will depend some on the parallel/series configuration. Not knowing the specific panels, if all 6 are in parallel, the max Amps might be up around 80, but could be lower. Once you finalize the battery bank voltage and then pick the solar charge controller the configuration will make more sense.

Note that a simple number like "2" on the Cooktop hours creates the big number of 3,000 watt hrs. Recognize that those are AC watts and because an inverter might only be 90% efficient, you actually would need about 3,333 DC watts from the battery to run it. But if you adjust your cooking patterns to only need 50 minutes in a day, the system demands drop a lot.

There is an art to building a system to "meet the needs of your lifestyle" but there is also an art to adjusting a lifestyle to "fit within an available system". No judgement here - just can be fun (and hopefully not too daunting) to ponder the options on both the input and output ends.
Jono14 is offline   Reply With Quote
Old 04-24-2023, 12:27 AM   #5
Bus Crazy
 
Join Date: Oct 2020
Location: Near Flagstaff AZ
Posts: 1,951
Year: 1974
Coachwork: Crown
Chassis: "Atomic"
Engine: DD 8V71
Jono makes a good point about the energy consumption of the cooktop. Just guessing "2 hours" may not even be close. I would spend the $30 or so on a Kill A Watt and do some measurements of your appliance use at home. You might be surprised...you might not. But at least you'll be accurate.

rossvtaylor is offline   Reply With Quote
Old 04-30-2023, 10:35 AM   #6
Mini-Skoolie
 
jbeech's Avatar
 
Join Date: Mar 2019
Posts: 58
The major benefit of LiFePO4 over LiIon cells is ruggedness. That, and a pack made up of LiFePO4 cells may remain fully charged with no issue while a LiIon pack should not be stored at full charge for any appreciable period of time. The downside of the former (LiFePO4) is they're rated at 3.2V/cell versus 3.6V/cell so you're going to need to check your math at the margins.

Now let me help put ruggedness into context. I'm a model builder (RC model aircraft). We use packs made up of both types of cells, plus one more, LiPo (3.7V/cell). Moreover, we routinely charge/discharge them at higher rates than in RV-use. Higher rates just means we're more abusive of them. This is good in terms of learning dos and don'ts.

Note 1 - while I would never recharge a LiIon pack whilst mounted within a model (balsa, foam, fiberglass construction, think great tinder for starting a fire if you're a Boy Scout), I routinely will recharge mounted LiFePO4 packs. Why one and not the other? Greatly reduced fire risk with LiFePO4 cells compared to LiIon (and hugely less than LiP0). Fire? Yes, fire is a MAJOR consideration with any lithium chemistry pack and LiFePO4 cells are a LOT safer in that regard, followed by LiIon, and LiPo last of all (most dangerous).

Tesla? LiIon cells. Tesla fires? In the news for being hard to put out. Bear this in mind. And I'm not picking on Tesla because Hyundai, Chevrolet, and recently Ford are all on record at some point or another warning against parking within your garage due to there being a risk of fire. Think your RV is immune? Think again!

Note 2 - think carefully about the house chemistry. The OP has posited using LiFePO4 batteries, and I congratulate them for it. I would use the same approach with the principal difference being I'd rather four 100A batteries than each 400A battery. Yes, means 12X 100A batteries instead of 3X 400A units - but this is carpentry versus architecture.

Maybe my view will be viewed as quaint or archaic so maybe I'm wrong or lacking in data, but I'd rather deal with one of my 100A packs going south on me than the equivalent of four packs going south on me at once (I use the term battery and pack interchangeably as they're both made up of individual cells).

Speaking of which, and FWIW, if you open any one of these 100-400A 12V battery packs, you'll see they're actually made more like a Tesla-pack, e.g. comprised internally of a butt load of individual 18650 cells. As an aside, this also means you can go in and replace a defective cell (or ten) and bring the entire pack of 100 cells, or whatever, back to life. In theory. And you do know those packs (Ford, Tesla, Chevrolet, all of them) are water cooled, right? THINK!

This brings us to voltage . . . typical 400W panels are 42V, making them great for dealing with 36V systems. Three 12V packs (batteries) in series become 36V, or in parallel remain 12V. If it were me I'd rather deal with moving 36V around as the wire gauge is reduced compared to flowing the current at 12V. Just saying.

Note 3 - regard wiring and sizing. Dealing with DC amps and wire gauge is tricky. I'd advise buying an infrared temperature gun. Like the ones hospitals used at the beginning of the pandemic when they took your temperature aiming at your forehead. What for? Check the temperature of the wire you've installed when loaded. Basically, heat is bad juju and a great indicator you're too light in the gauge department. Use your judgement by accounting for how long a load will be in place.

Finally, I am nobody to give advice on consumption, but it strikes me the advice of using Watt-meter is solid. And these things are available in more configurations than the Kill-A-Watt device mentioned. This one is good to 180A and will prove a useful tool. Using it is easy but practice can be tricky because the question is, what connector do I use? Sadly, there is no one standard.

Note 4 - on my business-website we sell three convenient to use connectors rated at 30A, 60A, and 90A (DC amps, totally different from AC amps). These connectors are, however, widely available so I am 'not' shilling them to you guys as they're merely an accessory, meaning not what we 'do'.

Anyway, these types of connectors are a handy way to establish 'your' standard for testing and interconnecting some devices. And maybe not obvious, but anything flowing more than 90A of current will need something else. FWIW, this same brand makes one available to 150A, it's just that we don't handle the larger ones preferring to opt for a bare 5.5mm bullet connector instead because the plastic housing for the 150A is bulky and thus, somewhat incompatible within the space constraints of model airplanes. Anyway, the point is you should establish 'some' interconnect standard and then begin testing some of these things.

Earlier I mentioned fire risk so allow me to bring up fire, e.g fire on purpose (and yes, I do this a little bit tongue in cheek). Why? It's because 'I' prefer cooking on fire and thus, a gas eye makes more sense to 'me' because it removes a huge resistive load from DC-power consideration. To which I will add; an instant-on gas-powered water heater is compact and adds another approach to the luxury of hot water. One that will greatly reduce electric current demands on your system. But, of course, everybody has their own take on perfection.

What I'm saying is, pick and choose your battles because an all-electric setup may, or may not be wise. As always, it depends.
jbeech is offline   Reply With Quote
Old 04-30-2023, 11:40 AM   #7
Almost There
 
Join Date: Jul 2018
Location: Canada
Posts: 81
Year: 1994
Coachwork: International
Chassis: Thomas Vista
Engine: DT 408 6.7L
Rated Cap: 72
My system, and a great resource for builds

Hello! Good start, but it seems your system is overbuilt, many aspects seem to be overpowered, or just not properly calibrated for your needs.

Here is a great link to a blog with so much info, great diagrams and parts. He's great, I learned a lot from him he will help you a lot https://www.explorist.life/category/...-and-diagrams/

Now..

Here is an overview of our system, we have a 36ft bus, full-time live in for two digital nomads. I have a DC fridge and run 2 X computers, 2 X 32" monitors, tv, etc etc so my power demands are high. I use these all day long.

24V is great for a heavy draw, bringing down wire gauge etc, but appliances are harder to find here is North America, 12V appliances and items are easier to find. So plan this accordingly to your needs.

Lithium Ion are amazing, but watch cold weather charging, get heaters or store them well.

My system is as follows:

- 12V
- 800W solar (8X100W renogy Panels)
- 2000W Victron Multiplus Inverter/Charger/Transfer switch
- 400Ah Lithium Ion Renogy Batterys (4X100Ah Renogy)
- 150.85 Victron Smart Solar

I've also attached an image of our wiring diagram to give you an idea. Please do not just follow it, as there may be things I changed on the fly for safety ( I AM NOT A ELECTRICIAN) but its a good visual to give you an idea what someone else did, and has used for a year with no issues.

So, my battery bank does well at 400Ah. I can go through it quickly if I use a heater or something at 1000W but in general no problem, I would consider going up to 600Ah to really be very comfortable.

My 800W solar panels can draw me 30-40A in good sun, it's enough to run all my electronics and charge generally. I am considering adding 2 more panels to max out my charging and be happy.

and finally my 2000W inverter is overkill already, and at 12V I don't even want to know the draw if you got a 1Kw inverter fired up, it would just be death to your battery bank. I doubt you need more then 2000, unless you plan to run like a microwave or something, but I would recommend getting rid of these items.
Attached Thumbnails
Artboard 24@2x.jpg  
__________________
Learning from my mistakes... slowly! - Check Out Our Bus Build Thread - https://www.skoolie.net/forums/f11/s...408-28471.html
scloughcarroll is offline   Reply With Quote
Old 04-30-2023, 12:26 PM   #8
Mini-Skoolie
 
jbeech's Avatar
 
Join Date: Mar 2019
Posts: 58
Very neatly done schematic. What software did you use?

For my 24' box, I'm planning on a mini-split for cooling (we're in the SE and unlikely to ever need heating). But if we did, am leaning toward using an electric blanket. Anyway, I'm leaning toward eight +400W cells (or as many as I can fit). Anyway, I'm not close enough to even be planning as the press of business has me hopping so outfitting the rig remains 2nd order for now.

Finally, I very much enjoyed poking about that reference site, thank you. That, and reviewing your schematic. Well done!
jbeech is offline   Reply With Quote
Old 04-30-2023, 12:38 PM   #9
Almost There
 
Join Date: Jul 2018
Location: Canada
Posts: 81
Year: 1994
Coachwork: International
Chassis: Thomas Vista
Engine: DT 408 6.7L
Rated Cap: 72
Quote:
Originally Posted by jbeech View Post
Very neatly done schematic. What software did you use?

For my 24' box, I'm planning on a mini-split for cooling (we're in the SE and unlikely to ever need heating). But if we did, am leaning toward using an electric blanket. Anyway, I'm leaning toward eight +400W cells (or as many as I can fit). Anyway, I'm not close enough to even be planning as the press of business has me hopping so outfitting the rig remains 2nd order for now.

Finally, I very much enjoyed poking about that reference site, thank you. That, and reviewing your schematic. Well done!
Thanks! I used Adobe Illustrator, I'm a designer and editor so it's intuitive. Although I need to give credit to https://www.explorist.life/ because I got the plan and idea for the schematic from him. I customized his 2000W/3000W plans as a starting point and built out and adjusted all the wire gauges and fusing.

I actually have an entire PDF of my bus build with schematics for my layout, plumbing, wiring, etc. It was a lot of work but helped me to visualize my plan and what I needed to buy.

I want to do a mini-split, but I just need a good mounting point close to my interior mounting place, a job for later on I guess.

I am in Canada, so I need heat more, and AC for only 3 months. I use a 5KW diesel heater, it's cheap and amazing. I am now installing some new AC for the summer, so deciding on that one.

I do use a generator when I'm using AC, or only run it short and then charge. My system is not large enough to run something 1000W pull plus all my other stuff for more than an hour or so.
__________________
Learning from my mistakes... slowly! - Check Out Our Bus Build Thread - https://www.skoolie.net/forums/f11/s...408-28471.html
scloughcarroll is offline   Reply With Quote
Old 04-30-2023, 01:03 PM   #10
Mini-Skoolie
 
jbeech's Avatar
 
Join Date: Mar 2019
Posts: 58
I have Illustrator as well but am more intimate with Photoshop and InDesign. Frankly, I am a total dunce with regard to Illustrator as my drawing needs are more along the lines of CAD. And while there are CAD tools expressly for electrical layouts, that's not my forte, either (mechanical).

Yes, if I were in Canada, then AC needs would be as low on my list as heat is for me here in Central Florida! Meanwhile, I'm estimating a need for more than 2000W to start the compressor and running loads will be 1200W-ish. The system is sized more with cooling in mind than anything else as lights, small appliances (refrigerator, coffee maker, and microwave), plus television, computer, etc. are of vastly more limited duty current draw. As long as there's enough to run the air conditioning and a microwave, I'll be happy.

Add to it, long term camping is not our use-case - weekend model airplane events within 400 miles is more like it. Trips beyond that we're more likely to take the Bonanza (an antique airplane) and stay at a hotel.

Not much on cooking, either, because events attract loads of food trucks. Since I'm of the economic belief everybody has to eat (earn a living), then I'd rather pay someone who is there to expressly to feed people than duplicate their work. I work hard enough M-F so this also means more time for running my mouth with friends.

This is the beauty of forums like this . . . we have all kinds of use-cases and points of view. Only thing absolutely not on my RADAR was buying a diesel pusher with marble countertops. Our rig is little more than glorified camping in comparison.
jbeech is offline   Reply With Quote
Old 05-16-2024, 04:52 PM   #11
New Member
 
Join Date: Aug 2019
Posts: 1
what is the blue box coming off the battery switch ?
Seabass is offline   Reply With Quote
Old 05-16-2024, 05:09 PM   #12
Almost There
 
Join Date: Jul 2018
Location: Canada
Posts: 81
Year: 1994
Coachwork: International
Chassis: Thomas Vista
Engine: DT 408 6.7L
Rated Cap: 72
Quote:
Originally Posted by Seabass View Post
what is the blue box coming off the battery switch ?
It is the Victron Lynx power in, its a modular DC Busbar, so it distributes power out to my various outputs, and also holds the 4 larger fuses for each item
__________________
Learning from my mistakes... slowly! - Check Out Our Bus Build Thread - https://www.skoolie.net/forums/f11/s...408-28471.html
scloughcarroll is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


» Featured Campgrounds

Reviews provided by

Powered by vBadvanced CMPS v3.2.3

All times are GMT -5. The time now is 01:33 PM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2024, vBulletin Solutions, Inc.