Our portable solar suitcase setup

jkjenn

I love how you took everyone's ideas and ilfinesed them. The box looks very good and Will try that same thing after this trip.

I also love the baby bumper corner guards. Brilliant! Renogy has corner guards on my 50w panels and they look like they were 3-D printer produced. 

I was able to find less eclxelnsive folding legs on ebay.

BrianZ

Hey, @Sharon_is_SAM, you taught me a new word - "upcycling"!

Yeah, @jkjenn, I wish Renogy would make your 50w corner guards available as an addon for other panels, but guess they don't want to compete with their own suitcases.
I'm just not sure how well the bumpers will stay on in warm weather, but I have all 8 corners covered.  It's very handy when mounting, dismounting, storing, or setting on the ground.  Would be better if corners could be covered by a single piece instead of two bumpers.

Sharon_is_SAM

@BrianZ - guess I have been on Pinterest, too much:)

2Cougs

@BrianZ- Are you worried about trusting it overnight or in windy conditions?  We are looking at a roof mount (either on the T@b or the tow vehicle) so it can also charge while traveling.  Obviously it would be flat while traveling, but the selfie sticks could work to bring it up to angle once at camp.

BrianZ

I'm not sure, @2Cougs, maybe a little.  I'm looking for a security cable to lock the panel to something secure when set up on the ground, but for wind, I plan to try a pair of tent pegs & some cord to anchor each selfie stick to the ground.  I think that would address the wind, but really I'm not too worried about high winds, which are relatively rare here in VA, not like out west.  We've lived in Texas twice, and it was pretty windy out there.

I was just finishing up some roof mounting details & testing today - a clamp, new corner bumpers, brackets, and routing a 15' cable pair from the roof mounted panel to trailer tub.  I'm considering testing it out en route for keeping the frig running, depending on weather.  I managed to tap into a body panel bolt for attaching a velcro strap to secure the panel cable pair at the rear of our Sienna van.  Will post some photos when I get a chance.

BrianZ

@2Cougs, the selfie sticks do seem to work well, but as you pointed out could benefit from some additional support against strong winds.  

I've drawn on this photo to show how I plan to attach cords to caribiners that I have added near the corners and attach them to tent pegs in the ground.  I've added 2-inch bolts to the threaded sockets on the bottom of the selfie stick handles, & cut the heads off so they can stick into the ground to prevent slippage.  Similarly, it might be a good idea to put a couple of tent pegs in the ground in front of the panel to prevent it from slipping out.

This shows my completed car roof mount..

I've got pads under the suction cups just to prevent them from sticking while making adjustments, because they do have a very tight grip.  BTW, that little ridge of rubber on top of each cup should stick out so you can pull on it to help release them.  I bolted on 4 generic aluminum Z-brackets near the corners to fasten caribiners attached to the roof rack as safety chains.  What keeps it snug are the two larger custom brackets on each end that are bolted to the luggage rack.
I also got rid of the smaller clear corner guards which came loose, and replaced them with larger ones with more surface area of double stick tape. (Roving Cove Soft Baby Proofing Table Corner Guards https://www.amazon.com/dp/B0198RCRFG)  They are thicker & provide more cushioning, so hoping they will stay on better.  If not, I'll use a stronger glue.


The custom end brackets are Renogy Z-brackets that I bent to fit my luggage rack.  I first installed a bolt with T-nut inside the inner groove that the rack's cross rails slide in.  The bolt sticks out from the rack slot and fits through the slot in the lower portion of the Z-bracket.  I then added the round black lock nut (from a piece of photography gear) with matching 1/4" x 20 threaded hole to lock the bracket tight against the rack.  The prongs that project over the panel hold it down, and are protect the panel from scratches by the added strips of auto door edging leftover from the sewer pipe storage tube mod.  Because there is not enough space to get fingers around the lock nut for tightening, I drilled holes in it so I can use a nail as a lever for tightening.


I knotted the panel extension cable around the luggage rack & routed it down the nearby rear pillar.


At the position indicated, I fastened a velcro strap to the car for holding the panel cable in place.  In retrospect, I should probably reverse the panel & route it down the passenger side in case I should need to stop & check it.


A closer view of the velcro strap, which comes out from the space next to the trunk lid.


To attach the velcro, I used a copper plumbing pipe strap, which has holes at each end, flattened it in a vice, then bent it into an L-shape and fastened with an existing body panel bolt.  I inserted the strap through the other hole so the two ends were hanging free, then fastened them together with an aluminum rivet.  Then I can simply wrap one strap around the cable & the other end over it.


From there, I put the cable through a hole in the spare tire rim, then inside the tub from underneath to connect with the charge controller mounted inside the tub.  I may add another velcro strap to the spare tire mounting hardware for securing the cable there to prevent slippage.  I'd be curious to see how others may have done this cable routing, but couldn't find anything, so thought I would share how I've done it.  (To be tested within the next couple of weeks.)


And finally, here's the view inside our now full tub, showing locations of charge controller box, connectors (disconnected), and battery monitor shunt box.  Battery is a 12V 150Amp-Hours Trojan 1275 golf cart battery.  Sewer hose end elbows connected together fit securely In the space shown between battery, gas tank & tub wall.  A plastic screw cap container of gloves is below that inside of a 4-inch piece of the original white pipe that I cut & remounted.
And as porky once said, That's all folks!

PS:
All photos are 600x800 or less!

BrianZ

I tested the tent peg idea (for fit, not actual camping yet, but that will be soon) with tie-down cords for protection against wind..

Here are the features I added to our 100W Renogy Eclipse panel.  The four Z-brackets with caribiners near the corners were originally added for securing to TV roof, but are handy for tie down cords.  These corner bumpers seem to be holding up better than the small clear ones I used originally.


The Z-brackets & caribiners near the bottom corners are also handy for adding tent pegs directly for securing the bottom of the panel against slippage.  Also drilled a hole for a padlock by going through the side of the frame to avoid contact with the glass panel.

dbruening01

Thanks for this. I put everything in my cart for future purchase. I have no idea what I am doing but the dealer said I should look at zamp solar and it is very expensive. I just want something to allow me to boondock for a few days at a time. This looks perfect!

Photomom

Basic question: the specs for both the Victron 75/15 and the Victron 100/75 are the same, 220 amps at 12 volts. There are a whole bunch of other Victron models with varying specs. How does one determine which controller to use?

For example, if I were planning to start with 2 of the 50 watt Eclipse panels but have the capability to add 2 more 50 watt panels, what controller would I get?

A link to someplace that explains this is fine.

rajamar

Photomom said:

Basic question: the specs for both the Victron 75/15 and the Victron 100/75 are the same, 220 amps at 12 volts. There are a whole bunch of other Victron models with varying specs. How does one determine which controller to use?

For example, if I were planning to start with 2 of the 50 watt Eclipse panels but have the capability to add 2 more 50 watt panels, what controller would I get?

A link to someplace that explains this is fine.

Get the 75/15. Victron's model numbers refer to the maximum volts and amps coming in from the solar panels. A 100 watt Renogy 2 panel suitcase has an "open circuit voltage" of 21.6 volts and a "short circuit current" of 6.0 amps. That's the theoretical maximum output of the panels.

200 watt of panels, depending on whether they're in series or parallel, would have  an output of, at most, 43.2 volts and never more than 12.0 amps.
Here's how that works:
______________________
When wiring solar panels in parallel, the amperage (current) is additive, but the voltage remains the same. ... If you had 4 solar panels in a series and each was rated at 12 volts and 5 amps, the entire array would be 48 volts and 5 amps.
________________________
The 75/15 is more than adequate.

The output of the controller (what goes into the battery or contributes to the total system load) is measured in watts which is volts x amps. The Victron's are smart controllers - they take whatever watts are coming in and send out the required voltage depending on the charging stage. As sunlight and clouds vary the panel wattage output, the controller sends voltage out between 13.8 and 14.4 volts but varies the current (amps) between 0.1 and 6.0
Screenshots of my 75/15 at different panel output wattages:

Sharon_is_SAM

We bought the inexpensive Renogy PWM 30 amp Wanderer and it does just fine with our 100-200 watts.

Photomom

I don’t understand why you’d connect two panels in series to produce 24 volts nominal if you have a 12 volt battery.

jkjenn

Photomom said:

I don’t understand why you’d connect two panels in series to produce 24 volts nominal if you have a 12 volt battery.

In simple terms, an MPPT controller can take a higher voltage and convert it back down to 12v. The controller then maximizes when you have sun and charges faster. 

I found this particularly helpful on days where I needed to fully charge earlier (moving to a new site) or when there were just brief periods of sun.

BrianZ

Great point, @jkjenn.  This morning after our first actual boondocking night, our panel got up to 70 watts as soon as the sun came over the trees & got us back to 100% within 20 minutes, though we were only down to 94% after a night in the 40's with Alde & frig on propane, an hour of TV last night, some lights on, etc.

2Cougs

Hello @BrianZ- I am much in appreciation of your documentation along with @AldebaranJill 's as I design and install our 100W Solar System.  I have a question: Do you see any issue with placing a Victron Monitor shunt in the same water tight container as the Victron Solar Monitor?

BrianZ

Interesting idea, and good question, @2Cougs!  As to the "Solar Monitor", I assume you mean the Solar Charge Controller (SCC) in the water tight box.  I may have to ponder this a bit, and maybe we'll get some other opinions in the meantime.  My initial thought is I'm wondering if both would even fit.  Maybe so, but it might get crowded with all the cables.  Some use a bus bar in conjunction with the shunt, so that could either complicate things or maybe reduce the number of wires going into the box.  In any case, I'm inclined to think it may depend on how or how much you plan to use your solar. 
 
For us, we will likely be using hookups more often than solar, so I view the solar/SCC setup & box as more of a temporary thing that will be disconnected and stored while not in use, which is why I adopted the @elbereth setup, though it wouldn't have to be that way.  On the other hand, the battery monitor is more of a permanent thing that is useful all the time, so deserves a permanent mounting.  I can even check my battery status via bluetooth from inside the house, while the trailer is parked in the driveway. 
  
So, I never even considered installing the SCC permanently, but see no reason why it couldn't be done.  I just feel better having an expensive piece of electronics stored in a safer place while not in use most of the time.

ChanW

(This thread is very helpful. Excuse the resurrection)

Do I understand correctly that another reason to combine two panels in series is that the higher volts/lower amps can use a smaller gauge wire with reduced voltage drop?

Photomom said:

I don’t understand why you’d connect two panels in series to produce 24 volts nominal if you have a 12 volt battery.

ScottG

Good question. In general, wires are sized to handle the maximum current (amperage) that they will be expected to carry. This is a safety concern to avoid overheating and creating a fire hazard.

To what extent this factors into the voltage drop issue is unclear to me, though I suppose you could experiment a bit with an online voltage drop calculator. If nothing else the higher voltage coming from the panels would likely mitigate the effect of the drop to some extent. Of course, you would have to have a controller that would actually utilize the excess voltage rater than waste it.

Ultimately, whether or not a series configuration would confer an advantage in the real world is outside of my pay grade. I'm interested to hear what other have to say. 

ChanW

Ok, it sounds like the primary reason to go in series is to get the higher voltage so the controller can be more flexible with its charging modes.

I had the understanding that a big reason to go to 24V in a series configuration, was the ability to use smaller gauge wire, and run a longer distance, if your panels are 'remote' from the controller & battery bank. (Then again, I might have simply surmised - I find that I do that a lot ☺️) Maybe it's just a secondary benefit to the series setup.

So can the MPPT controller take a low input voltage, and lower the current, and thus increase the voltage, for a better charging curve? ie with a single panel (non series) setup?

ScottG

I'm not aware of that capability with an MPPT controller, but again this is stretching my know how.

Anecdotally, it seems to me like panel voltage generally comes up before panel amperage, so what you ask might be a moot point. This is based solely on observing panel output under different conditions, not on any special knowledge of solar engineering. Hopefully someone can set us both straight...

BrianZ

I think the purpose of using a series connection is not only to take advantage of the MPPT controller's ability to use virtually all of the power without extra high current & heavy cables, but also to salvage remaining voltage from non-bypassed cells in partially shaded panels.  Am I out of luck with that right now, using just one panel?  I'm not sure it matters how many bypass diodes mine has if it's not in series with another panel to achieve the minimal voltage, right, or can one string get you there in good light?

The same watts of power can be transmitted as either high voltage/low current or lower voltage/higher current; but the higher the current, the larger the cable required to provide lower resistance to avoid heating over distances.  Commercial power distribution systems use the same concept to transfer power over high voltage lines from the power plant to your local neighborhood, where transformers reduce it to lower voltage for transmission over shorter cables to your house. 

As far as the voltage drop issue, lets do the math! ..
Below is a comparison of the line losses when transmitting the same 48 watts of power over a 30ft cable using different volts & amps.  The first two show at 12V/4A versus 24V/2A using the same 10G cable, there is a 75% reduction in lost power using the higher voltage method.  The third shows that even using the 24V/2A method with a thinner 14G cable, there is still a 30% reduction in power losses.
I only chose these V/A values to make the math simpler to understand, not to represent actual panel voltages, but the same ideas apply.

ChanW

Thanks Brian. That's what I was wondering, and you explained it perfectly.

I'm thinking a second panel will be in our future, for efficiency's sake, even if not for need!

ScottG

I never paid much attention to the basic voltage drop equation, but since it's directly proportional to current, @ChanW's original supposition that series wiring could allow for the use of smaller gauge wire seems to be confirmed. Thanks, @BrianZ, for running the numbers on this.

For better or worse, I now have another topic to ruminate on with regards to how best configure a second panel.  :-)

BrianZ

I found Jenn Grover's past discussions of her four 50W panel configurations interesting, particularly how she used 2 parallel strings of 2 each in series to get the advantages of both methods.
In my very limited first experience last fall, we got by just fine for 4+ days with a single 100W panel, but we were never without sun for very long, had no issues with shade, and had cool weather for highest panel efficiency, so ideal conditions.  I don't know if we'll ever really need another panel, but if so, I have room on the luggage rack for a second panel and a series string on the ground.  Or a T@B roof mount could use a parallel connection with an optional ground mount.  With our 150AH battery, we never went below about 90%, and I think we'd be ok even with 2-3 cloudy days, but a second panel would help in that situation to get caught up with recharging without having to go into survival mode.

ChanW

@BrianZ, I've been trying to figure out which selfie stick you found on Amazon. This looks closest, but the bottom has a tether loop. Is the loop removable?

https://www.amazon.com/Luxebell-Adjustable-Telescoping-Monopod-Session/dp/B01DY0A6E2/

BrianZ

@ChanW, yes, that appears to be the one.
I believe I unscrewed & removed that strap & there was a tripod mount with a standard 1/4x20 threaded socket.  I cut the head off of a bolt & screwed it in there for sticking into the ground for my solar panel supports.

ChanW

Ok, thanks Brian. I like it! And thanks much for going to the effort of so thoroughly documenting your install. You might just find a few of us have re-used your good ideas!

(I should say 'thanks, everyone in this thread'! - it's been extremely helpful seeing how so many have implemented their install... Thanks everyone.)

ChanW

I've been examining my new Victron MPPT 75/15 controller, and have a question about weather resistance.

When peeking inside, it looks like the whole internal shebang is sealed in epoxy or some such, that is, everything except the screw terminals, fuse, jumpers, and LEDs.

IOW, it seems to be weather resistant, at least enough to depend on inside the Tab's front tub.

Do we know if Victron considers it water resistant? I can't find anything in their documentation that says yea or nay.

How come folks are installing it inside a waterproof plastic box?

I'd think a little dielectric grease protecting the wire connections, fuse blades, and jumpers would be enough to prevent problems.

Thoughts?

Photomom

ChanW said:

I've been examining my new Victron MPPT 75/15 controller, and have a question about weather resistance.

When peeking inside, it looks like the whole internal shebang is sealed in epoxy or some such, that is, everything except the screw terminals, fuse, jumpers, and LEDs.

IOW, it seems to be weather resistant, at least enough to depend on inside the Tab's front tub.

Do we know if Victron considers it water resistant? I can't find anything in their documentation that says yea or nay.

How come folks are installing it inside a waterproof plastic box?

I'd think a little dielectric grease protecting the wire connections, fuse blades, and jumpers would be enough to prevent problems.

Thoughts?

I assumed that people were installing them in waterproof boxes because there wasn’t room inside the tub. I have the metal tub and am planning to install my Victron inside it.

ChanW

I missed that detail! Thanks @Photomom

To finish the subject...

About my question regarding the water resistance of the Victron controller, I received a reply from the dealer I purchased from, 'Remote Power Source' (Amazon).

They said:

They have an IP43 rating:
" protected against sprays of water from any direction " 
(Not submersible)