Power On

Yesterday the final connections were made between the solar panels and the controller.  The weather was partly cloudy though and the motorhome was sitting in the driveway partially shaded by some pine trees.  Under these conditions the performance was pretty bad, with the charging current registering less than 3 amps on the Trimetric battery monitor.  It was late in the afternoon, so I decided to put the motorhome back in the storage for the night.

Today, the morning clouds started to clear up around noon so I went back to the storage and backed the rig out into the sunshine for another test.  Much better!  Now the batteries are seeing a charge current of better than 15 amps.  I tilted the panels up 30 degrees using some temporary pieces of wood and the current increased to 18 amps.

Panels Soaking Up The Sun

View From The Top

All Panels Wired In Parallel To A Common Point

The Trimetric monitor was showing a small load on the batteries of approximately 1-2 amps before turning on the solar system (I'm not sure from where yet).  The monitor measures all current into or out of the batteries via a current shunt.  This means that the current from the solar controller is actually 1 or 2 amps higher than that shown on the monitor.  This would put it at 19-20 amps (with monitor showing about 18 amps).  This is right in line with the sum of the rated currents of the panels.

17.9 Amps Net Current Into The Batteries

 

The next test was to turn on the Xantrex 2000 watt inverter and power up the 120V system.  I then turned on the 26" LCD HD television, DVD player and the refrigerator (running on propane, but still drawing a small amount of current from the 12V system).  Still getting a net current of 5 amps into the batteries.

That's it!  The system is now operational.  With time left over to watch some of the Masters golf tournament on solar power.

Solar Power

Here is some info on the solar battery charging system that we are currently in the process of adding to the motorhome.  It is our intent to be able to live normally (except for running the air conditioners) and bring the batteries to a full state of charge on reasonably sunny days without plugging in to shore power or running the generator.  The system I am installing is patterned closely after the one described in HandyBob's blog (see "Blogs We Follow").

The system will consist of the following components:

2 Kyocera 135 watt panels (Vmp = 17.7V. Imp = 7.63A)
1 UL Solar 85 watt panel (Vmp = 17.9V, Imp = 4.84A)
1 Morningstar Tristar TS-45 45 amp PWM solar controller
1 Bogart Engineering Trimetric 2025-RV battery monitor
1 Xantrex 2000 watt inverter
4 6V Interstate Workaholic deep cycle batteries (total 464 amp hours)

Below are some photos of the equipment that has been installed so far.

Deep Cycle Battery Compartment

The bundle of wires running down to the batteries on the right hand side includes the following:

#4 AWG cables to solar controller
Battery voltage sense wires to solar controller
Battery temperature sense wires to solar controller
Battery current sense wires from shunt to battery monitor
Battery voltage sense wires to battery monitor

Also shown above are the 60 amp DC circuit breaker and 500A/50mV current shunt.

Xantrex 2000 Watt Inverter

Inverter, Starting Battery & Deep Cycle Battery Compartments

Solar Panel Disconnect (Left) and Tristar Solar Controller

Disconnect and Solar Controller - Covers Closed

In the above photos, a standard one-pole air conditioning disconnect is used to allow the panels to be disconnected from the controller.  Both the disconnect and controller are mounted on the wall of a closet just above the deep cycle batteries.  Note there is no wiring installed yet to the panels.

Trimetric 2025-RV Battery Monitor

The battery monitor shown above is a key part of the system.  After calibration, it can display battery charge status in a simple "percent full" format.  Both current and time are constantly monitored, recording amp-hours in and out of the battery.  It can also display instantaneous battery current, voltage, time since last full charge and time since last equalization.

85 Watt Panel Manufactured by UL Solar

Aluminum Angle Mounting Bracket w/Stainless Steel Hardware

Panel and Cream

Above are some of the last components yet to be installed, the panels themselves.  In parallel with the 85 watt UL Solar panel shown, there will be two Kyocera 135 watt panels, bringing the total ideal maximum output to 355 watts.  The maximum power voltage of the panels is 17.9V and 17.7V respectively, so they should parallel fairly well.

The aluminum angle mounting brackets will attach directly to the motorhome roof with stainless steel lag screws.  All the metal parts used in the installation will be either aluminum or stainless steel.  The panels will be capable of being tilted up to approximately 45 degrees either left or right.  The optimum tilt angle is approximately equal to the latitude of the location and facing due south.  Ideally, the panels should face directly toward the sun at noon.

More info will be coming later after the panels are installed.