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Seriously look at the economics of drop in batteries, vs building your own, we live in a world where import 100AH LiFePo4 batteries commonly sell for $190 or less online, even ones with bluetooth BMS are only a few dollars more. With 280-300AH batteries selling online for around $550 - $600

Weight considerations are an important factor in any such van build

It sounds like you have a plan, I too would likely downsize the inverter in your situations, but would probably drop down to a 2,000 or 2,500 watt high quality model

To add the last post it helps to understand that wire sizing is somewhat exponential as amps go up. Meaning a tiny little 18 gauge wire will handle about 6 amps of DC power, but to carry 60 amps requires a fairly large 4 gauge wire (this is the size seen for battery cables on small cars), and...

Don't forget to keep track of how much all this stuff weighs, and keep your gross vehicle weight rating in mind. Years ago I had a friend that rebuilt an old TransVan camper van with all new cabinet work, got done and realized it was too heavy to drive, had to tear it all out and start over...

True, but in the US the NEC requires an 80% derate of capacity, limiting appliances to about 1,500 watts maximum actual power draw. This is usually seen as a max amp rating of 12.5 amps for appliances, and some slight variation on wattage depending on line voltage ie 115, 120 or 125 VAC

Here are my thoughts on a 1,000 vs 2,000 watt inverter, (assuming quality inverter, not a cheap one that fails to deliver its claimed performance) with a 1,000 watt inverter you will always be asking yourself, will the inverter power this or that, for some stuff like a modern TV, notebook...

It depends on what you want to power, also be aware a lot of cheap inverters seem to have rating specifications written by the marketing department which are "aspirational in nature". Just be aware a single 200 watt panel will take a long time to fully charge a pair of depleted 100 ah...

I guess we just differ a bit in design choices, personally in a RV situation, I prefer to have native 12V deep cycle batteries, preferably at least 2 of them for redundancy, that way in case of a failed battery / failed BMS things will still work, and such a component failure would not ruin a...

An MPPT only doing 700 watts max output with 800 watts worth of panels is not typically an issue in van / RV applications with flat mounted panels as due to lack of tilt the number of hours per day that they achieve rated output is much lower, in other words those 800 watt panels are likely only...

With all due respect here, I can see your point on larger RV's but we are talking about what appears to be a Sprinter van based on avatar photo, so roof area will be limited to about 4x15 feet (roof rails on most sprinters are about 51 inches apart). Realistically you are not fitting over 1,000...

I admit pulling 3KW from 12V using 4/0 is a limitation, however in most setups that is only running from the battery to an inverter located perhaps 36 inches or less away, in other words not that big of deal either in weight or cost penalty, such a pair of 3 ft cables will weigh in at around 4...

I tend to feel you are right on the cusp of either one being a practical choice, therefore I would lean 12V dues to easier parts availability, etc. My rule of thumb is that 48V make sense at over 800 to 1,000 watts of solar panels, or over 3,000 watt combined total discharge rate.

I too think an air dam at the front to raise the airflow over the panels is a better solution, remember air flow under the panels will tend to cause lift, which might pull the panels free of their mounting or break the glass.

True, but some go to 14.8VDC which is more of an issue

I agree with most of this mornings messages, but feel that some of the nuances of your installation are not addressed, for example I suspect you would be ok with just your existing charge line from your tow vehicle without the need for a DC-DC charger, though perhaps at less than optimal...

double post

Ah, you have a point, I was multi-tasking a bit when I wrote my last reply, should not do math in my head

Why do you say you can't leave it floating? I understand why not floating would moderately extend the life of the batteries, but I don't see why you say you can't leave it floating.

You might want to double check those numbers, some of them don't seem to pass the sanity check (the max amp draw numbers) for a 12V system which you mention using in your initial post, and which I would assume from talking about wiring in parallel, as a rule of thumb you can expect about a 100...

Note you can't just mix and match solar panels like that without taking potentially major performance hits, see https://solarpanelsvenue.com/mixing-solar-panels/ and https://footprinthero.com/solar-panel-series-and-parallel-calculator

You will need a second battery, the one you specified has a 250A BMS, which is not large enough to support a 3000 watt inverter at max amp draw. Rule of thumb you need AT LEAST 100A of BMS rating for every 1,000 watts of inverter capacity, and this is with no real safety margin. Therefore you...

I personally feel a 3000 watt inverter is right at the largest inverter that is practical with a 12V system, and given your likely loads, a high quality 2000 watt inverter might be a more practical choice, just be aware a lot of the cheaper inverters out there seem to be rated by wishful...

I have not seen such jumping as you describe in 50A RV panels, only in 30 to 50 amp RV adapter power cords, or in RV transfer switches to allow a 120V generator to provide power to both sides of a 50A RV breaker panel, while providing 120/240 split phase to the panel when plugged into a 50 amp...

You tell us what you are wanting to do, but very little about the RV itself, and how you plan to use it. You say right now your current 12V loads are a constant 50-60 amps, I have to wonder why? I have a 28 ft Class A motorhome, (which I suspect is smaller than your RV as you say you have 3...

I can power the Sharp R7A85 convection microwave (discontinued model) in my motorhome with my Xantrex Prowatt SW2000 pure sine wave inverter, which is rated at 1800 watts continuous power, 3000 watt surge, which is powered by a pair of Rebel brand12V 200AH LiFePo4 batteries wired in parallel...

You might be able to spin the screws fast enough to get undone with an impact driver without holding the nut.

Thanks for the catch there, I will be using something larger than 8awg, probably whatever I have on hand for the run, which is about 4 feet, maybe a bit less from the Victron 100/50 to the distribution block. Imp is 9.65 amps, so just under 30 amps combined for 3 panels.

Thanks, I will be using 10AWG wiring between the panels with 20A MC4 fuses on each of the LG panels, and 8AWG or larger between the Victron 100/50 to the main power distribution blocks.

You can use this calculator to determine mismatch losses in various wiring configurations https://footprinthero.com/solar-panel-series-and-parallel-calculator In this case with 3 old and 1 new panel, it looks like parallel or series are your only viable options with less than 4% losses...

Yes it is, how go your travels?

It would be tempting however right now I have less than 4 inches of clearance between the top of my air conditioner, and the roll up door in my storage shed.

That probably makes sense I spent several hours last night running through the variations on this while looking at overhead photos of the RV, and it seems I would need to have 2 Grape panels wired in series, and 2 of the LG panels wired in parallel for it to make sense to keep them, with 2.87%...

I have been playing with the mix match solar calculator here https://footprinthero.com/solar-panel-series-and-parallel-calculator and it seems to suggest my best bet may be keeping all 4 of the 100 watt panels wired in series then adding 2 of the 305 watt panels in parallel loosing only about...

I have an older (installed in 2015) 400 watt solar installation on my motorhome which uses 4 100Watt Grape Solar GS-STAR-100W (VOC 21.9, ISC 6.13), I have also recently acquired a number of very lightly used 305Watt LG NeON (VOC 40 ISC 10.1) panels from a hurricane damaged installation, that I...