Hey @Zwy, I just wanted to say thanks again for your reply on this thread. I was skeptical, but at your advice I did go shopping again, and found the unusual Renogy 100W "Slim" panels. These are only 13.8" wide! So I went back to playing "Rooftop Tetris" again and you are so right! I was able to...
This is the best forum ever! Damn. You folks respond fast with great insights!
@Brucey, thanks for the wire size feedback. My intention on that is over-engineering. The batteries and the other components that I showed using 4/0 AWG wire will will be inches apart from each other with cable...
That's awesome @B-ManFX4 ! Thank you so much! I actually looked on Mouser before posting but apparently my searching skills are terrible.
A related question but maybe this is the wrong forum. I am planning an isolator switch for the solar panels, and a breaker for the battery side. But I have...
Wow! 3 replies already. I love this forum!! Great points, @Rocketman. And I read your Mixing/Matching link, @chrisski. And thank you too, @Mattb4. Given this, I reconsidered and played some more rooftop Tetris. I can place 4 *identical* 12V, 200W panels on my roof (with some difficulty -- one...
Some background (why I chose this specific design):
I have a small (24 foot long) motorhome with a 30A shore service. I have designed an off-grid 1kW solar array (the most I can fit on the roof) and a 10kWh battery bank with a 3kW inverter so we can sometimes "boondock" when we travel (i.e...
I see tons of DC breakers rated at 48V but I am thinking that a breaker that is rated for 48V is not safe for a 48V (nominal) system. My 48V system will actually run at about 56V. It seems I can buy fuses rated at 58V and above, but I am struggling to find a appropriate *breakers* for this...
Thanks @time2roll ! And ouch! I changed up the solar array from my previous design but forgot to recalculate the controller. Will fix. THANKS!
I did not know Victron made 48V-to-12V converters. I'll check that out.
Good point on the 100A fuse too. I sized based on the max charge rate of the...
I wrote 400A for the wire because that is the battery peak discharge amperage (15 sec) but I fused it in the distributor to cap it at 200A because that's the max continuous discharge rate of the battery. And yeah the "Multiplus II 48/3000..." is 48V 3000W.
Ahah! Good catch on the 8AWG. 8AWG maxes out at 55A apparently! As you note, that's fine for now, but for 100A (if I ever get there) I will need 6AWG, which enables 41ft for 56V@100A to keep it below 3% loss. So I wil use 6AWG, I will also use 10AWG on the panels (which will keep it under 3%...
Thanks @sunshine_eggo! I'll check out that shunt.
Lol. Sorry. I'm not buying 95ft of 2/0. I'm just noting the maximum length of that gauge wire at that voltage and amperage. My little RV is only 24ft long so I would have a hard time using 95ft of wire. Where I am locating things the inverter...
Thanks for replying with such detail! All of this is very helpful to me.
I like the above suggestion very much and will put a switch on each battery. That will be very convenient.
Good point. Once I settle on the final PV array, I'll re-size the MPPT appropriately. From discussions in another...
I forgot to respond to your SOK battery comment. I did look at SOK, but I can't fit a comparable SOK battery bank in the small compartment where I want to put my batteries. The EPOCH batteries are similar in build, but 48V (which tend to be smaller per Wh) and internally heated (I travel to very...
Cool! So I think you are saying I could use multiple MPPTs (in parallel) in this system (connecting a subset of the panels to each. Is that right? I guess then I would have to have multiple wires going through the roof. And I would essentially have multiple completely independent solar arrays...
I read Will Prowse's very helpful book, read product specs, watched videos, and dove right in to designing a solar+battery system for my 24ft motorhome. It would be great if you experts could comment on how this looks so far. I haven't bought anything yet. Here's my first draft of the design...
I agree it would be easier but my unfortunate space constraints are holding me back from that. To get the same (in kWh) storage capacity with 24V batteries takes too much room for my tiny "wiring closet" (which originally used to be an actual closet, lol). However, your excellent suggestion to...
These panels are all 12V with different wattages (and physical sizes and shapes) in order to maximize the wattage I can squeeze onto my RV roof. My friend called this playing Tetris with the various panels I could find from a large number of vendors. I haven't bought any yet, but this 800W...
Lol. I hope you don't. That sounds rather unpleasant.
I just copied/pasted the product documentation about the -25C (https://www.epochbatteries.com/products/48v-100ah-lithium-server-rack-battery-size-3u-ul9540-pending)
The SOK 48V/100Ah batteries are certainly sweet hardware, but they are...
Yes, sorry. I meant the MPPT, not Muiltiplus II. When the breaker trips, the solar will remain connected to the MPPT, and I think I read that this is a problem. Maybe I need to go back and re-read the MPPT documentation?
This is my current design schematic (haven't bought any of it yet):
Yes. I see. Two of those are just slightly larger than the 48V pair and provide the same kWh total. Then I could switch to a Multiplus II 24/300/xx. That would make Vbat+5 charging easier (anything over 30.6V to start). Thanks!
The battery bank will be in an interior cupboard area and my plan includes forced air ventilation from/to the living space. I think it will normally be well above freezing in there (or we will be frozen too!) I originally felt I needed heated batteries because I was thinking of a different...
24V is looking pretty good to me now, but I remember reading somewhere that the rule of thumb is to use only up to 1kW of A/C loads with a 12V system, up to 2kW loads on a 24V system, and then to use 48V systems if you will ever have loads greater than 2kW.
What do you all think of this rule of...