What size panels can my 100/20 Smart Solar handle?

[67cj5]

The Solar shop who sold me my 100/20 said I could run 4X 150w panels in 2 banks of 2 panels or run 6 panels in series Max.

 

[dreadlocks]

6x 150W panels @ 22V is 132v in a series and would nuke a 100v max 100/20

You could run 4 panels in a series with a 100v input ceiling on the Renogy 150W specs I just grabbed randomly, but it would be pushing it in the winter.. would be better suited for 2 typical 36v house panels in a series

 

[67cj5]

6x 150w @17.5v = 105v, Splitting the 6 panels in to 2 banks of 3 would drop the voltage to around 52.5v / 60v and give around 14 to 18A.

22v/132v @ 80% = 105.6v, Getting a full 132v is almost impossible depending on the conditions but in winter time they would supply enough voltage to keep the batteries topped up depending if they were split in to 2 banks of 3 or one bank of 6.

 

[Chris Boyd]

A fridge is one of the best mods I’ve done to my truck for overland style travel. The problem for me was I could cover all of my power needs if I was moving every day, letting the ICE catch up,the overnight depletion. Occasionally we’d find that spot we wanted to be in for multiple days, usually out in the sunshine, like a beach or field for a music festival, etc. then I’d be chasing electrons all of the time.

The goal of my system was to be able to cover the usage of the fridge to run all of the time without intervention, except for those days where we didn’t have enough solar yield, or we used more than normal power for lighting, showers, charging drone batteries, etc.

I feel like I’ve gotten there with a 160w panel mounted on my RTT permanently. I can run the fridge all of the time, enjoying the irony of warm sunlight cooling my beer. Now, the sun is recharging the batteries before I even wake up and by noon the battery has recovered whatever the fridge usage was overnight. Having the SmartSolar app and watching how the solar harvest is going has helped my understanding.

Generally speaking It’s important to understand your usage and study the battery loads without solar and then balance the sun loading you’ll get in the regions you’ll be traveling. Of course over-paneling helps, but I don’t have the roof real estate. When I build a Sprinter in a few years, that’s the approach I’ll take!

My advise is just get it installed based on the basic math and then compulsively monitor the SmartSolar app history and you’ll get a sense if you have figured it right on paper.

 

[DiploStrat]

Yes for most "normal sized" mostly-solar rigs, even a small fridge is the vast majority consumer of Ah, and to have any chance of only-solar I would reco 200Ah and 2-300W of panels.

Northern winters in PNW type conditions more panels.

IMO ICE power should be there as an occasional backup.

Not that I want to get too holier than thou, just my background is full-timing off grid for years at a stretch since the 80's.

I accept some really need to have the mod cons or they simply can't get away from the S&B home at all.

I would agree with every one of these statements.

Many of us are in campers because we spent decades living out of the back of a pickup or similar, so I WANT MY MTV! (OK, in my case, a guitar amp and an espresso machine, but the concept is the same.) Also, there is a difference between a "camper" which may only be used when the weather is appropriate and and a 'round the world overlander, which has to keep folks comfortable for months at a time, summer and winter.

But worth repeating:

-- Refrigerators may be the first, best modern convenience, but even a small one will suck way more power than most expect.

-- Good sun will deliver about 5A per 100w of panel and refrigerators can easily pull 5A. Will the vagaries of real world sun, this means that you typically won't see much benefit from solar until you hit at least 200w.

-- Exceed 1500w of solar and you may not need engine (ICE) back up, but for most of us, a vehicle's alternator can be a great source of bulk charge. As I have all electrical appliances, the engine is a great way to spare the batteries after a week of rain without driving.

-- I have friends who argue strongly that there is a point of diminishing returns with battery and that a small genset is more practical than an extreme battery. You should do your own cost benefit analysis.

-- A dual battery disconnect, "So that I can be sure I can get home" is generally a symptom of a system that was not properly sized to carry the load. Done right, you will never need your starter battery to carry your camper/house load and vice versa.

YMMV and all of the usual caveats!

 

[john61ct]

Hi DiploStrat, now I know the context, sorry

Yes been playing with alternative energy a while now. Lived most of my life overseas no mod cons, outhouse/dunny, water from the village well etc.

So I am appreciative every time I can get light just by flipping a switch, amazing!

Agree with all that post, but note that

**if** running ICE for charging only is a regular thing, LFP's advantages are much more compelling.

Reduced ICE runtime pays back even big investments pretty quickly.

IMO isolated Starter is essential for anyone boondocking with only one vehicle.

 

[DiploStrat]

...
IMO isolated Starter is essential for anyone boondocking with only one vehicle.

Agree. I just mean that you should not design a system with so little power and so great a load that you depend on the dual battery isolation to save you. I think of it more as a fuse than as a control element.

 

[john61ct]

Better IMO to think of it as a combiner system

since in a properly implemented system, Starter is **always** isolated when there is no source active,

so it never supports any House loads anyway.

I realize you understand this, just clarifying for posterity, other more noobish readers

 

[DiploStrat]

Actually, that is an excellent way to describe it - the default is isolated; it only combines when a charge source is available.

FWIW: Magnum actually refers to their unit as a Smart Battery Combiner. Great minds!

 

[john61ct]

The woman who invented them (ACR / VSRs) called them that originally.

Ann-Marie Foster, of Yandina Ltd, still in business, fantastic products, lifetime warraty & support.

Back when isolators were based on diodes and had hella voltage drop.