Solar - Fixed or Portable addition?

[obiwan_canoli]

As I work through the process of upgrading batteries, either a 4-jar bank of Lithium 100Ah 12V, one 300Ah + a 100 Ah, or two 200 Ah, I'm also researching the addition of more solar panels to the roof of my Class A. My boondocking plans in the years to come require a more serious look at power needs and requirements.

Currently, I have 3 - 160W solar panels - 26.1 amps total output, fixed to the roof, a 30A PWM Controller, and have room for up to 4-5 more panels, depending on configuration. Of course, will need a new Controller if I do so. For the solar wattage I'm considering, some sites have suggested an 80A MPPT Controller. I initially thought a 60A would do the trick, but I was basing that on the total amp output of all panels. I also have a 120W, 5.6A portable.

I'm thinking I might be better off using portable panels. As a practical matter, at 100-120W per portable panel, I'd need at least 3, probably 4 to reach my goal of 40-50A between all.

It might make sense to have some of my charging capacity in panels I can move around when shade impedes. I understand some can be hooked together, but then, there's the inconvenience of having to store, set up, and take down 4 folding portable panels. Space is, after all, at a premium... Perhaps just two?

I understand each person will have different needs and requirements, but is this a balance some strike, where solar is concerned? Or are there 'druthers out there who swear by one way or the other? Further thought makes me wonder about adjustable tilting panels that DON'T require me to climb up on the roof twice each trip! Too old for that...there must be a creative person out there who's come up with a method of adjusting the roof panels from ground level... an engineering type that loves to tinker...? 

As an aside, I have a Trav'ler II mounted to my roof, but have considered picking up a portable sat dish - again, when I find myself in the trees...

[richard5933]

Couple of thoughts...

Rooftop solar is handy, in that it's always there ready to go. But, it requires you to park in the sun for it to work. Hard to keep the bus cool if you're in the sun without running the a/c, and if you are able to run the a/c usually that means you're plugged in or on generator. In that case, you don't need solar.

Rooftop solar is handy during cooler times of year where a/c is not as necessary, but then the sun is lower in the sky and not as effective.

We decided to start our solar with ground-deployed units. We have three Zamp 180-watt folding units and can charge at 30-40 amps easily. We set up the three folding units to run in series instead of parallel, which give higher voltage and lower amperage. This allowed us to run a 50-foot cable to connect them to the coach, and having such a long cable means the coach can stay in the shade while the panels are out in the sun.

Having ground-deployed solar has proven to be a blessing up here in Wisconsin where the sun is at a lower angle in the off season and where it makes a really wide swing in summer. We can angle the portable units to capture as much of the sun as possible, and in the summer will try to rotate them through the day to capture sun from dawn to dusk. Hard to do this with rooftop solar where the panels are generally speaking flat on the roof.

Our charge controller is capable of running much more voltage and amperage than we currently have available. Eventually we hope to add a few panels to the roof. While we've found the ground-deployed panels great if we're going to be somewhere for a few days or more, they tend to be annoying to set up for just a day or two. With a few roof top panels we'll be able to charge the batteries on shorter stays easily, and even while parked in a lot out seeing the sights.

Make sure that whatever you get for your charge controller gives you room to grow. It's easy to run out of capacity if you only get one big enough for the first few panels. Much easier and less expensive to just get the larger unit to start with.

[obiwan_canoli]

As I continue my research on batteries, charge controllers, additional solar and how it all comes together, LifeBlue Lithium batteries were suggested, ns upon review, it appears these are specially constructed to operate and charge at lower than 32 F. This seems to be the most advanced version of Li's, for the charging range is from -4 to 119, according to the data sheet on the site... If this is accurate, seems to me this is the ideal battery for RV's...

 

Wondering if anyone has experience with the brand, and, of course, the charging issue at below freezing temps... think this is accurate?

LifeBlue Li 200Ah low temp version

[jleamont]

21 minutes ago, OBIWAN_CANOLI said:

4 to 119

So I wonder how that would hold up crossing the Mohave Desert in summer? We did that in 08 and it was 122 that day outside, I cannot imagine how hot the basements were in the RV. 

Edited August 28, 2020 by jleamont

[richard5933]

21 minutes ago, jleamont said:

So I wonder how that would hold up crossing the Mohave Desert in summer? We did that in 08 and it was 122 that day outside, I cannot imagine how hot the basements were in the RV. 

The datasheet indicates that the batteries can be charged from -4F to 119F. Apparently they can be discharged at temps up to 140F.

When I read your post though, my question immediately was why cross the Mohave Desert in summer? Isn't that typically done at other times of the year?

[obiwan_canoli]

5 hours ago, richard5933 said:

The datasheet indicates that the batteries can be charged from -4F to 119F. Apparently they can be discharged at temps up to 140F.

When I read your post though, my question immediately was why cross the Mohave Desert in summer? Isn't that typically done at other times of the year?

Perhaps rescuing a damsel in distress... I should have noted the 140 degree high side but that was discharge only...

[jleamont]

6 hours ago, richard5933 said:

Isn't that typically done at other times of the year?

Not when you want to get to Disneyland, it’s July and you know your gas coach would climb the mountains on the other route but never stop going down them, you opt for the hot route . Co pilots idea! 

[manholt]

Richard, by contrast, it gets very cold there also.  Like death valley, 120+ daytime & 30's or lower at night.

[rsbilledwards]

First suggestion read the site handybobsolar.com for a comprehensive take on solar 101,102 and 3, what really works and what does not. He has no fiduciary interest in any of the recommendations. He is an electrical engineer, retired living in a totally o ff the grid solar based home in Montana. He like the tried and true when it come to batteries, so, it is up to you on that point. I have 960 watts up top and use two Bogart Engineering chargers which work great recharging the 780 amp hours of Crown wet cells in the battery bay now in year year 6. Real considerations are the charging parameters and how efficient given units really are and how adjustable. There is a lot of no solar being sold these days. I know of several friends that have enough solar up top that still use their gennies because the charging mechanisms fail to make the grade.