Solar System
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    Installing a Solar System in 1998 was both responding to past power-outages and anticipating times when electrical service might not be available (as in boondocking).   Having lived in the trailer full-time since 1994, I had experienced times when the utility company was not delivering and yet I wanted both to be warm and to have light / power by which to work. A small UPS back-up-power-supply for the computers was adequate to let me gracefully shut-down when the power failed (and is still a necessary unit in my opinion). However, getting urgent work done required more.
    What I installed goes beyond the traditional "one panel and one battery per person" rule. This rule-of-thumb is quite adequate for recreational uses, the original "recreational / marine duty" battery in the trailer was sufficient for summer weekends without any charging.   Because I was running computers and staying in a location that gets cold during the winter, I needed more.

What I installed:
    4 x 55-watt Siemens solar panels ( each 3.1 amps at 17.7 volts )
    tilting roof-top panel racks
    #10 wire from panels to junction-box on roof
    #6 wire from junction box to charge controller
    12-volt-dc lightning arrestor
    Heliotrope RV-30S pulse-width-modulating auto-equalizing tapered charge controller
    #6 wire from charge controller to shunt and fuse on way to batteries
    100-amp fuse
    200-amp shunt (to allow monitoring all input / output to batteries)
    2-0 welder cable (flexible, high conductance wire) to batteries
    3 pairs 6-volt golf-car/cart batteries
    2-0 welder cable between batteries
    Hydro-Caps for batteries (catalytic recombination of hydrogen & oxygen back to water)
    Heart Freedom-10   1000-watt inverter / charger with remote
    20-amp short shore-line on input to inverter (actually #10 wire/cord with 20-amp plug)
    50-amp plug-receptacle on output of inverter for trailer shore-line connection
    240-volt-ac lightning arrestor in trailer breaker box

Some notes on the install process:
(( need to gather some more & better photos to organize this section ))

Panels On Roof 1           ( <-- link to picture, click to open in new window,   if you use a "pop-up blocker", you may need to change the settings to see them )
Ignore the little man behind the curtain and the dents on the roof -- those are part of another story.

There are four solar panels mounted in pairs on tilt-able bases. The wires from each of the panels come to the small box in the center of the roof where they are connected to the two wires leading down to the controller.

 Panels On Roof 2
The lead wires from each panel have outer vinyl tube for added protection. All four wires go into the flexible plastic conduit that leads to the small roof-top junction box.

This panel position is the default tilt angle (that can be reversed).
 Panels On Roof 3
Panels On Roof 4

Panels On Roof 5
This shows the alternative supports I built using shorter aluminum angle struts.
 Panels On Roof 6
Panels On Roof 7
Panels On Roof 8

Panels On Roof 9
This shows the panel in its horizontal / travel position. Note the reinforcement angle aluminum across the ends of the two panels.

 Wire Run 1
Since the battery compartment is in the rear on the driver's side, and all the other vents "out of reach", a new hole in the roof was required.

Most of us fuss about putting a screw hole into the roof -- a natural paranoia of RV owners about water leaks. This was an 1+1/4 (1.25) inch hole. The conduit fitting has a compression ring to clamp the roof sheet metal.
 Wire Run 2

Control Panels 1
The bathroom is in the back of the trailer, the battery compartment takes up the lower section of the cabinets / closets on that side. This meant the control panels would be back here also. The back of the panels are exposed in the closet, thus adjusting the dip-switch settings and access to in-line fuses is fairly easy.
 Control Panels 2
Due to the lighting, the LED display on the solar charge controller is not visible. It displays current voltage or amps from the solar panels or the total amps in-to/out-of the battery depending on a slide switch setting.
The two 'household' style switches with pilot lights control the Blue Cord and the outlet in the battery compartment respectively.

 Battery Compartment 1
OK, it looks a little messy -- however this is just 'truth in advertising'. This is the original battery compartment plus shore-power-cord storage compartment.

The original stuff is:
1. the brown box on the upper left is the back side enclosure of the 120-volt circuit breaker panel box;
2. the vertical wood bar is the original place to wrap up the shore power cord;
3. the white "hump" on the bottom left is the top of the original battery box;
4. the large coiled up cord is the original 50-amp shore cord.

A lot has been added.
1. the brown wire in the upper-left is an interior phone line;
2. at the bottom left you see a light colored extension cord loop up, over and then into an original outlet in the compartment (this outlet is now on an interior switch -- see control panels);
3. the pair of blue cords dropping down from the top of the compartment are from an extension cord - split in the middle, switched inside (see control panels);
4. extending out the bottom of the circuit breaker panel box is a silver labeled 240-volt lightning arrestor;
5. just to the right of the lightning arrestor is a GFI-ed self-regulating heat cable for the black-water tank freeze protection;
6. the green coil of wire is a supplemental safety-ground line to connect to a spike in the ground when the TT not otherwise grounded;
7. in the upper-right back of the compartment is the 50-amp receptacle that is the output of the inverter;
8. just below and to the right is a junction box containing the "shunt" that enables the charge controller display to show the amps to/from the battery(ies);
9. in the tube below the shunt box is the 12-volt 100-amp fuse;
10. at the bottom left are two 2-0 welding cables that go to the external battery box, the light colored 'box' into which they lead is a disconnect;
 Battery Compartment 2
Battery Compartment 3
The cords hanging down outside the compartment are:
1. two 2-0 welding cables (with sun shielding covers) that go to the external battery box;
2. a telephone cord (hidden);
3. two extension cords going out to heat-tape protection of the water hose and a heat-cable in the battery box;
4. an extension cord comming in from a 15 amp service;
The connection configuration as shown is:
* Outside extension cord to switched Blue Cord,
* Switched Blue Cord to input to inverter,
* Inverter to outlet box,
* Outlet box supplying shore cord and hence remainder of trailer.
I change the connection configuration to suit the circumstances.

 Battery Box 1
Since I don't have the funds for a Motor-Home or large Fifth-Wheel, the battery bank lives outside the trailer in a metal box with 1-inch insulation. (The medical logo is left over from my days as an advanced-life-support EMT.)
 Battery Box 2
The finned mushrooms are Hydro-Cap battery caps. These recombine the hydrogen and oxygen generated during battery charging back into water. This significantly reduces the need to re-fill the battery cells. It also reduces some of the explosion risk.
Inverter 1
Inverter 2

Where I obtained most of the system:
    Abraham Solar Equipment
    P.O. Box 957
    Pagosa Springs, CO 81147
    970-731-4675
    1-800-222-7242 Quote & Order Line
This is a family business which does not do the expensive marketing stuff (thereby keeping their prices lower). Please call their toll-free line only for orders, use the regular number for technical and before-the-sale questions.

Some things learned along the way:
1. Solar panels are rated in watts, but you need to look at the maximum amps they will produce.   Yes, Watts = Amps x Volts - - - however, the panels are current(amp)-limited devices, they will only produce so many amps, the same maximum amps at 12 volts, at 13 volts, at 14 volts … at 19 volts. Since you need to calculate your power consumption in amp-hours when looking at batteries, I suggest you stay in those units (amp-hrs) for all calculations.
2. The advantage of higher voltage output from solar panels is limited ( as another generalization ) to when the temperatures of the physical panels gets very high. There is a tendency for the panels to produce less when they are very hot.     I’m not certain I have every taken advantage of this in my panels. (And, as I get older, I’m not certain I want to hang out where it gets that warm!)
3. Tilting of panels, especially during the winter, can increase their output. However, the RV must be parked just right for the panels to point toward the south. Further, getting to the edges of the panels that are to be lifted/supported can be difficult.     When the panels are "up" they become sails: now the wind (especially strong gusts) becomes an issue.
4. Having solar panels on the RV requires parking the RV in full sun -- forget those nice tree-shaded sites. (For those considering wind powered generation, consider that you will need to park where there are nearly constant 20-mph winds.)
5. You need to have a battery-backup UPS for your computer always. I can run the computer from the modified-sine-wave inverter. However the APC backup UPS does not think the power is clean enough, so it goes into its own internal stand-by mode. If money were no object, a true-sine-wave inverter would be preferred.
6. Batteries are both heavy and take up space.

A special thanks to those contributing to make this system possible.


This page last edited: 11 April 2005