Extreme 400 watts on rear shell

BrucePerens · 07-24-2016, 02:20 PM

This is a work in progress, not all of the mounting screws are installed in this photo. After they were installed, I could lift the trailer by the solar panel frame and jiggle it on the rubber axle. The frame is designed so that all of the weight (about 80 pounds) rests on the walls of the shell instead of the roof, and the frame is anchored into the shell frame. I copied this mounting area from the brackets on the Fiamma awning.

I can still open the rear shell without trouble before adjustment. I might have had it adjusted for too much lift before. The torsion bars have some adjustment range left and we'll see how far that goes.

This is 400 watts on the rear shell, and an additional 300 will go on the front, to bring the input to my MPTT to the maximum open circuit voltage of 150 volts. Panels are Grape Solar GS-STAR-100 polycrystalline. Rather than intending for it to output 700 watts, it's intended to work in partial shade and output 100 to 200 watts during typical usage. Each panel has three separate banks with a bypass diode on each. The MPPT is currently limited to 29 amps charging because I only have one pair of GC2s, I might install a second pair. The MPTT is a Morningstar TS-MPPT-60 with Ethernet.

There is lots of air circulation under the panels, as the full array of 7 panels would lose 1.75 watts capacity per degree Farenheit. The rear shell array shades the rear bed area. The center and edges will be taped with aluminum sealing tape to rain-seal the face of the array. The array is slightly inclined toward the rear and projects about 2 inches beyound the rear roof edge (but not beyond the lights and window cover). The frame provides good places to mount a backup camera and lights.

The frame has three 1 inch aluminum L members on the long axis, screwed to the solar panel frames, and two 2 inch aluminum L members on the short axis. Solar panels are screwed together on the short axis at the center. The two short axis L members are resting on a 1 inch square tube which rests on the roof edge. The tube adds an inch of height to make up for the peak in the shell roof, so that the center of the frame doesn't contact the roof. Screws go through the 2 inch L and the tube into the reinforced roof edge.

I wonder if this could reduce the need for the TV alternator while towing? Some slight mileage gain possible there.

The stick-on conduit and wiring are next.

LoveToCamp · 07-24-2016, 04:45 PM

Well, that is quite the array! I don't believe I have need for 400w, but each have our own power consumption.

It is good that you still have lift capacity in your torsion bars. I have found that the rear, for whatever reason, seems to have more capacity, even with thinner bars.

Once you have your front panels on, you won't be worrying about hail! Panels can withstand bigger hail than the roof, I believe.

BrucePerens · 07-24-2016, 06:18 PM

There's the Dometic CR-1110 compressor 'fridge. And a lot of electronics. When we use the 1.3 kilowatt ham amplifier, we still have to bring the generator.

Padgett · 07-24-2016, 07:35 PM

Well that will certainly shade the bedroom.

scrubjaysnest · 07-25-2016, 08:35 AM

Looking good Bruce. We are finding here on the Blue Ridge Parkway partial shade is dropping panel output by 90%. That is really hurting us with the power hog we now have. Also 200 watts and sun chasing is barely covering our daily usage. That's at least one fan for 24 hours, power about 4 watts, electronic refrig controls at 9.6 watts plus unknown phantom loads. One of those we have to live with is the B.I.R.D at about 12 watts. That's a bydirection relay control device with time delay. It's main purpose is to tie the chassis battery and house batteries together anytime you charge the house batteries and their voltage goes above 13.1 volts or so. I may rip that system out this winter or at least disable it.

PM me when you get done and I'll add your install to the owners install links thread.

Ken

Padgett · 07-25-2016, 09:44 AM

Sounds like the system I had in my RV: One grp 31 AGM and two GC2s. Everything charged together and the starter battery would drop out at 11.6v. Was a turbo diesel so took a bit to start (glow plugs were 10A)

BrucePerens · 08-03-2016, 11:22 PM

I got the 400 watts on the rear shell working with my Morningstar MPPT-60 charger. It reliably delivers around 80 watts at 3 or 4 PM in the afternoon with smoke in the SF East Bay from the Soberanes fire near Monterey. No aiming.

At high noon there is a tree putting partial shadow on all 4 panels, and it delivers about 20 watts. So much for reliable performance in shade. I haven't tested it in a clear spot at high noon yet.

I want panels with a diode per cell, instead of per string, so that they'd be more shade-tolerant. The kind of diode necessary is a cheap surface-mount part, I don't know why nobody manufactures panels with a diode per cell.

Well, I know to park in a sunny area when boondocking.

BrucePerens · 08-11-2016, 10:19 PM

Yesterday I turned on the compressor 'fridge and left it going under solar power. Even with a tree shading my panels, there is unshaded sun for part of the day, and I came back at 1 PM a day later to find the battery at 100% charge. Solar powered 'fridge!

So, I'm ready to boondock.

gonzo628 · 08-12-2016, 01:29 AM

Where's the like button when you need it?

[email protected] · 08-12-2016, 03:15 AM

Quote:

Originally Posted by BrucePerens

Yesterday I turned on the compressor 'fridge and left it going under solar power. Even with a tree shading my panels, there is unshaded sun for part of the day, and I came back at 1 PM a day later to find the battery at 100% charge. Solar powered 'fridge!

So, I'm ready to boondock.

That is unless you really like to sweat!

...but I am glad you got your solar panel up and running. While you travel it should really work well out in the open! Now another 400 watts on the front? Wud-da-ya-think???

Tom .... who likes Bruce's 400 watt panel!