Monday, January 22, 2018

It is a Control Issue

I got together with a group of friends tonight who I hadn’t seen for a few years.  It was fun seeing these people who I used to connect with every week over softball.   …the couple years I was motivated enough to play softball, that is.  But now it had been a few years. The last time I saw them it was at the funeral of one of our players.  On the upside, at this happy hour none of us were dead.  But at one point we talked about our lives and our aches. The impact of aging.  No, we weren’t dead, but the yet was implied.

I have to confess part of the reason I have stretched out the installation of the solar panels over four blog posts is because it took forever for me too.  Everything about them went slower than expected.  The delivery, building the frame, rebuilding the frame.  It all took forever for me too.

In the meantime the solar charge controller has shown up.  It was larger than I expected it to be and on top of that, it requires six inches of headroom above what is truly an impressively large heat sink.  Where I had planned on installing this device won’t work at all so it was back to the drawing boards on that for a bit.  What I ended up coming up with, I have to confess I am really happy about.

Looking in from the back doors you can see my control
panel and how little space I have to go on the left.
My original plan was to have attached it to the back side of my bed, next to the back door, which has turned into my defacto van wiring control panel.  It has been sort of amusing/scary to me.  We have all had the experience where you start to hand write a sentence, maybe as you write and think you add another word.  Suddenly you start to look at the edge of the piece of paper looming closer.   You tighten up your words  and letters hoping to make it.   That’s called “kerning” btw for all you non-typography-geeks out there. It’s the same way with my control panel.  When I started out I had real estate between components.  The spacing has gotten tighter and tighter as I have moved across the board.

That’s why when the charge controller showed up I realized I had a problem.  The spot I was going to put it, because of it’s height, it would be hanging down interfering with propane tank swapping.  This stuff sure looks smaller on a five and a half inch screen!

All the wires going into the charge controller.
I had to find it a new spot but you know where I live.  I don’t have a lot of spots.  I thought about putting it up in the cab behind the passenger seat maybe. The advantage is I am closer to the solar panels and closer is better for voltage drop reasons.  But, looking at the thing, it has this huge heat sink on it.  Even a layman like me knows that means it must produce a lot of heat.   Do I really want to put it up in the cab where it is already going to be really hot?   All that extra heat could cause damage in the unit itself. 

For the same reason I ruled out putting in my living space.  I haven’t totally given up the thought of someday putting in a refrigerator.  Those put out a lot of heat themselves, I didn’t want to add even more heat to the living space.  Heck, I even thought about building a box for it under the van.  The perfect spot really except for all the road salt six (to seemingly eight) months a year.   Really when it came down to it though the only spot I had was back by my batteries and rear doors.  The area I call the garage.

The solar charge controller in its "swung out of the way"
postion.  When swung in, it is under the fuse.
I’m sittin’ in a bar right now so I can’t tell you for sure but I am thinking this unit is maybe ten by ten inches square and maybe fourteen high.  Then you have to figure the headspace of six inches it needs for cooling.  Some of the wires might have to enter the unit through the bottom, that adds even more apparent height.  I live in a world where a cubic foot is a really big deal.  There just wasn’t a whole lot of places I could even attach this thing.  The only place it could really fit was a place it was totally in the way.  It would be nice if I could install it there and then just swing it out of the way when I needed to.

In the end, that’s exactly what I did.  I used two pieces of 3/4” plywood and two large hinges.  I countersunk the hinges so the two pieces of plywood formed a book.  I attached the front cover to the charge controller and the back cover to the van.  Wha-Laa, I had the controller where it needed to be and would be able to swing it out of the way when I need access to the batteries or the inverter.  The multitude of wires I was able to run down the hinge line, then behind the “book” in the space with the weatherstripping so they stayed very much out of the way as well.

The patch I put in to cover the tear I made
in the insulation.  The patch doesn't need to be
water tight, it is to prevent oxidation.
The charge controller takes a lot of wires coming to it.  Number four gauge wires coming down from the solar panels, even thicker number two gauge wires going to the batteries.  Then all the other stuff.  There is a temperature probe that runs from the controller to the batteries.  There is a voltage sensor (thin) wire that has to go to your battery bank.  Two ethernet cables, one going to the van network and the other to the remote control panel.

The wires from the charge controller to the batteries is number two gauge jumper cables that I have cut the ends off.  Using the jumper cables had some advantages.  First off, it was cheaper to buy jumper cables than it was to buy raw wire from the welding shop.  The second, jumper cables are idiot proof!  I need that!   They are color coded red and black whereas the welding cable is any color you would like as long as it is black.  Henry Ford would be proud.  I did have one problem.  I needed to separate the two wires and did so by pulling them.  I wasn’t careful initially and caused some tearing of the insulation on the wire itself.  I caught myself doing it though and so was able to fix it right up with some heat shrink tubing.  I wanted a really good seal so I used three layers of tubing, one over the tear and two overlapping over that.  I feel confident it is air and moisture tight.

The faring coming up through the van roof.  Red for
positive, black for negative.
Up on the roof of the van I had two wires going to the solar panels.  So far they were just raw wires.  I bought some MC-4 connectors off Amazon.  They come in pairs, I really only needed one pair, wouldn’t hurt to have a backup.  Smallest quanitity you can buy?  Ten pair.   Ah well.  They were $20.  At the same time I bought a “Renogy MC4 Solar Panel Mc4 ASSEMBLY Tool”  because it was advertised on every Amazon page that other buyers had purchased one of these as well.  Total waste of money.  Only an extra seven dollars but they got me.   What you will need is something I already had, a crimp tool.  This tool locks the connector down onto the wire but doesn’t deform it so it still fits into the little plastic MC-4 bits.

The wire stripping guides to attaching these connectors are important.  This is something you have to follow the instructions and do it just right, otherwise you won’t get a water tight seal.  Once you get the ends crimped in place though it is slick, one solar panel connects to the other one (because my panels are in series) and then you just snap connect the two wires coming up from the van to the panels.

A nice sunny day in the early fall and
I am pulling in 337 watts at 25.3 amps.
It was a big job getting this all hooked up.  Really once this was done, dropping in the solar panels (once they fit) was totally anticlimactic.  After a test fit, I lifted the panels back out and drilled three holes per panel side through the side of the steel frame.   Then I dropped the panel back in and attached it with some stainless steel self tapping sheet metal screws into the aluminum frame of the panel.

I have been looking forward to this moment in the van project for a long time.  It is really an indescribably cool feeling to look at numbers the first time and realize you are generating electricity from sunshine.  Kind of like the first person who dug a hole deep enough in arid land and discovered water.  You realize that you have harnessed something willing to help you survive.

No comments:

Post a Comment