Solar Advice Needed - Renogy Solar Suitcase Install

[Mello_Mike]

I'm a long-time solar power user and have had solar power in my last three RVs. I currently have a 240 watt solar power system in my truck camper. I'll soon be upgrading my system from a Zamp PWM to a Morningstar MPPT controller. I just ordered a Renogy 100 watt solar suitcase which will allow me to aim an additional two 50 watt panels toward the sun. A huge bonus, giving me a total of 340 watts.

Here's my question: should I tap my new 100 watt suitcase into my current solar power system or keep the suitcase wiring to the batteries separate? The Renogy suitcase has a built-in 10 amp PWM controller, so I don't have to tap into my current solar power system if I don't want to. Just not sure which direction I should take. I don't want to make this installation more complicated than it really is.

I purchased a two-pole 12 volt plug and socket to connect and disconnect the suitcase from the camper. Does anybody else have a hybrid fixed and portable solar panel mount for their RV?

[Almot]

AH draw of compressor fridges varies a lot, depending on how well you insulate it. 70 AH for 3.7 cf is a bit on the higher side. These 12V units come from the factory poorly insulated, Canadian manufacturer Novakool recommends adding 1.5" or 2" thick block foam.

Old and low-end 110V units from big box stores are terribly inefficient, plus added 10-15% inverter losses. They've been getting better in the last 4-5 years though.

Weatherman rules, yes. AZ in January is about same good as Southern BC in May because chances of rain are lower. At Lat 27 in Baja on a good day in January my flat 490W collects - don't even know, must be upwards of 90 AH but I don't use that much, batteries are floating by noon. In low overcast with no blue sky and 50% rain it barely collects 25-35 AH by the evening, but... there is hardly one bad day a week there. In BC in May you sometimes have WEEKS of rain.

[BFL13]

Yes the non-propane fridge uses a lot of AH. We have a 3.2 cuft 120v fridge in the TC. The trouble off-grid is the fridge is on 24 hrs a day but the solar is only "on " during daylight hours.

Our fridge draws about 4.5 amps when it is "on" which is about 2/3s the time in 24 hrs. So that is 4.5 x 24 = 108 x 2/3 = 72AH

So add whatever the rest of your things in the rig draw, say 28AH, so you need to find 100 AH a day to stay even.

Here in May, I have measured that 130w lying flat will haul 56AH, so to get that 100 AH a day haul you would need about 100/56 x 130 = 232w lying flat. At 49.3N Lat in May on a perfect no-clouds day.

So the OP's search for more solar than 240 lying flat is understandable. Arizona in January is not the same as here in May. Everyplace is different!

BTW, to go off-grid (often we will have 15a shore power so no problem), I add the 255w panel to the roof of the TC (lying flat) and add two more batteries. There are two T-1275s in the TC and I put two 6s (from the 5er) into the truck bed ahead of the left side wheel well and leave linking wires hanging over the truck rail, then slide in the camper.

Then I bring up the dangling linking wires from the batts I can't get at anymore, to join wires from the house batts inside to make a four-battery bank.

After that it is all down to the weatherman how it goes. (No room for a generator (dog crates instead 🙂 ) The 7-pin charging from the truck is really lame so we pray to the sun god Kon Tiki in hopes the fridge can stay on for the week away off-grid before the batts get down too far.

Lesson is---keep the propane fridge if you can!

[Mello_Mike]

My Dometic CR-1110 3.7cf Compressor fridge eats between 50 and 70 amp hours a day which is why I'm adding a portable solar suitcase for extended boondocking. There's no problem when the weather's nice, but during freezing temps I need the extra amps to keep my 220 amp hour (two 6 volt AGMs) battery bank charged.

[Almot]

A nail-biter would be running a microwave with a small solar and no grid power ;)...
Counter-height 2.5 cu.ft 12V fridge draws 20-25 AH a day (compare to 10-15 AH of much bigger propane fridge). Still, a burden on a small system, agreed.

[BFL13]

Actually tilted fixed facing South does still collect during the shoulder hours, but you have to lower the panel from noon's best angle to get your single "optimum" tilt for the whole day.

If you do twirl it during the day, tilting is the opposite--highest earlier and later, and lowest at noon.

EDIT- must be time to inflict my old info on all that on the world again... 🙂

http://www.rv.net/forum/index.cfm/fuseaction/thread/tid/27734213/srt/pa/pging/1/page/1.cfm

With fixed South, it is possible to have the tilt so high near sunrise and sundown that the sun is "behind" the panel, but the amps then are so little, you aren't missing anything really. Macslab has a bunch of info on "optimum tilt angles" by season and location (latitude) to help with that.

There are contraptions for the roof mount that you can operate from the ground but the OP is not likely to be going that route.

The OP does not have a lot of roof real estate with a TC, so his basic idea makes sense. I "feel his pain" trying to run a 120v fridge off- grid in a TC 😞 It is a nail-biter all the way. Cloudy days can mean turning the fridge off and using it as an ice-box--if you can get ice. 🙂

[Almot]

BFL13 wrote:
Ground level aimed panel is subject to shading from the RV itself so you need lots of wire depending on how long the rig is and where the wires go to. Slide outs and awnings make shade too.

If that means the panel has to go in your neighbour's spot, you will have to instead, move the panel during the day from one side of the rig or from one end of the rig to the other to keep it in your own "yard" and clear of the rig's shadow as that changes location.

Ah, secret pains of portables that owners don't want to talk about 🙂 ...

Add more panels to the roof!

In the warm half of the year, the sun goes around more than 180 degrees. So if you place the panel out to the sunny side, it has to be far enough out to "see" around the back and front ends somewhat.

Tilted panel won't see much with the sun a few degrees behind. He'll have to rotate it at least twice a day.

Contraptions with tilted panel on the roof is not something to enjoy, either. You climb up and down few dozen times, and then it's not fun anymore. Tilted and portable on the roof would be the worst of both worlds - you'll have to climb to tilt and/or rotate it, and also to bring the whole cabooze up and down.

[westend]

If you have the Renogy charger on hand or on the way, I would suggest to initially leave the controller on the module and use the connector mentioned to run straight to the battery.If you choose to move the controller or parallel to one controller, you will have a baseline from the original.

IMO, the Renogy would deliver about the same wattage with controller on the module or installed close to the batteries (at 10'-15' distance). I wouldn't install the suitcase into a paralleled MPPT controller. Unless you're real lucky, the controller will be confused, AKA loss of harvest.

RJfishin has a cute portable mount that he uses, attached to a receiver, IIRC. One or two wooden sticks will work, too. If I went with a portable on the ground, I think I'd be looking for something like an articulated television mount on an upright. I'd have it possible to be quickly mounted at one end of the RV.

[BFL13]

The 10-15 feet estimate for distance from rig may not always work, so have extra wire to add on in case needed. (Some quick connect arrangement as invented for the situation)

Ground level aimed panel is subject to shading from the RV itself so you need lots of wire depending on how long the rig is and where the wires go to. Slide outs and awnings make shade too.

In the warm half of the year, the sun goes around more than 180 degrees. So if you place the panel out to the sunny side, it has to be far enough out to "see" around the back and front ends somewhat.

If that means the panel has to go in your neighbour's spot, you will have to instead, move the panel during the day from one side of the rig or from one end of the rig to the other to keep it in your own "yard" and clear of the rig's shadow as that changes location.

You can avoid a lot of that by placing your portable on the roof if you can get at it to aim it. That gets you into the world of "contraptions" though 🙂

[BFL13]

The 30a PWM can handle the 340w ok, so you could just add the extra 100 to that controller. That would be the easiest right off, then see how it goes for daily AH. If you still need more AH once you have tried it a little, then you might want to consider a more drastic solar upgrade anyway.

If you go MPPT on the 240, you must add the 100 separately to the battery via its own controller. The Vmp tracker works best with all same panels.

You could put the two 120s in series with the MPPT as 24-12 instead of 12-12 and get a bit more output in low-light or shoulder hours--no diff in high sun though.

You could yank one 120 off the roof and make that your portable and put the 100 on the roof instead (staying all PWM for mixed panels) That puts more of the total "aimed"

You could keep the money for the new MPPT, stay with the existing PWM, and spend that on a second suitcase 100. That would give you 440w.

Lots of choices!

[Almot]

If you have space left on the roof, you can add one more panel - as big as you can. 140W flat will work the same as 100W tilted. BFL will probably argue with graphs and numbers, that is is not quite "the same" during fall and spring seasons when sun is low, - but it won't be much different either. Last time I checked, AZ was pretty far South.

[NinerBikes]

Mixing different watts and different input voltages from different panels will confuse the MPPT. If you use a PWM charge controller and run all parallel inputs into a 20 amp PWM controller, you will get better results.

You will be lucky to get 5.5 amps out of a 100 watt suitcase solar panel. Don't ask me how I know this. I was lucky to get 6.2 to 6.3 amps out of my 120W solar panel in early October, aiming at the sun. Less in winter.

[Mello_Mike]

BFL13 wrote:
When you park the TC, do you unplug the truck to camper 7 (or 6) pin?
I do to keep the truck's battery from running down (Chev truck, no isolation)

That leaves the TC 7-pin socket empty, So you could add a 7-pin type plug to the battery wires on the suitcase (pin 4 and ground only) and just plug the suitcase (which has the built-in controller) into that, which will then charge the TC battery in parallel with the other solar set.

Not ideal for distance from controller to battery, but you still get something from it.

No, it's always plugged in. I have a battery isolater in my truck camper. Your idea has merit except I always leave my camper plugged in. It might work for someone else, though.

[Mello_Mike]

In response to BFL13:

-Is the 240 now two 120s in parallel nailed flat to the roof? or can they be tilted? Two fixed 120 watt panels in parallel
-will the two 120s be in series with the new MPPT (which affects options for how the 100 can be integrated) In parallel
-how many amps (size) is the PWM controller? (can you just add the 100 to that--very simple then) - 30 amps
-what do you expect to gain from changing the 240 to MPPT? Need every watt I can get out of my system for my new Danfoss compressor refrigerator
-how far away from the rig will you be deploying the suitcase set? Not far at all, about 10-15 feet
-100w will do about 6.2amps aimed at high sun. Why is that considered "huge?" What do you get now with the 240 as is? It's huge for me because my existing 120 watt roof panels are fixed. Not only does this suitcase give me another 6 amps, but it's aimed directly at the sun unlike the roof panels.

[BFL13]

When you park the TC, do you unplug the truck to camper 7 (or 6) pin?
I do to keep the truck's battery from running down (Chev truck, no isolation)

That leaves the TC 7-pin socket empty, So you could add a 7-pin type plug to the battery wires on the suitcase (pin 4 and ground only) and just plug the suitcase (which has the built-in controller) into that, which will then charge the TC battery in parallel with the other solar set.

Not ideal for distance from controller to battery, but you still get something from it.