Monday, November 25, 2019

Solar System Upgrades and Roof-Diet

We've been rocking a hybrid roof-top/portable solar system for several years now.  Having the flexibility to either use the panel fixed on the pop-top roof, or to unlock it and move it for better sun exposure has been excellent.

With our original 60w panel and an inexpensive PWM controller, we had a great budget solution, but it struggled to keep our house battery fully charged when the loads were high. (Usually hot days in the desert when the fridge works hard)

The other problem with the original system was one of weight on the roof.  After a couple of revisions, I had mounted the 60w panel towards the forward-end of the roof.  This made it convenient to pull it out of the rack while standing in the open driver's-side door.  However, having all that weight so far from the hinges made lifting the roof much harder, and it also put a lot of strain on the fiberglass.  Couple this with the fact that the roof tended to be overloaded anyhow (notice the fully-packed roof basket), and I needed to put the whole roof on a strict diet, while also upgrading our solar capability.

Note: Amazon affiliate links included below

And here's the new, more svelte roof installation.  Our new Renogy 100w "Compact" solar panel is the core of the upgrade.  This panel is thin and lightweight, but pumps out impressive power.  The panel is moved to the aft-end of the pop-top roof.  To make room, I got serious about narrowing down which gear we bring along.  I then swapped our massive Surco S4550 roof basket for, of all things, the basket portion of an inexpensive Aluminum Hitch-Mount Cargo Carrier.  The steel trailer-hitch bar and associated hardware were removed, leaving me with a very lightweight 49" x 22" x 7" cargo basket.

As with the previous installation, I wanted to retain the ability to remove the panel easily for optimal sun exposure, so I built a rack into which I can secure the panel.  The side rails are 2.0 inch "L" extrusions, and the end-portions are 2.5 inch "C" extrusions, with some shimming made from polyethylene to ensure a tight fit onto the ends of the panel.  Here I'm laminating some slider material to the side rails so the panel moves in/out easily.

As with the previous installation, the rack has three fixed sides, and one hinged end that secures with a padlock hasp.

More L-channel was chopped up to make mounting brackets.  1/4-20 bolts through these brackets mate easily with the T-nuts that slide into the Surco cross bars.

The final piece of the solar upgrade was to replace our 1st-generation Morningstar Sunsaver 6 PWM controller with a kick-ass new Victron "BlueSolar" 75/15 MPPT controller.  This does a much better job of optimizing the output from our Renogy panel, and when coupled with the Bluetooth Dongle, lets me both monitor history and customize charging parameters via my phone.
Overall, this has been a massive improvement.  With decent sun, we now generate almost in equilibrium with power consumption, meaning we can be off-grid almost indefinitely!  The effect of lightening the roof loads has also been pronounced - the roof raises much more easily now, and the van handles better with less weight positioned up high.

No comments:

Post a Comment