Our friend and mentor HandyBob consulted in the planning stages and installed the solar power system documented here. The system works superbly for our needs. I assembled this guide as a reminder to myself while the information is still fresh in my mind. I thought others might like to see it. In a subsequent post I’ll mention the batteries and our solar lifestyle.
Key to solar electronics photos
1 Wiring from solar panels
2 Solar input quick disconnect
3 Morningstar Tristar TS45 charge controller
4 Shunt for Tri-metric 2025 meter
5 Common ground
6 Main DC fuse
7 DC distribution panel #1
8 250 amp inverter fuse
9 Vent holes
10 Samlex 1250-watt modified sine wave inverter
11 Umbilical cord to tow vehicle
12 DC distribution panel #2 and AC breakers
13 Transfer switch and
battery charger switch
14 Shore power cable
15 Iota 30 amp
battery charger
16 AC receptacle for battery charger
17 AC receptacle
18 Converter was here; now removed
19 Bogart Engineering TriMetric 2025 meter
20 Remote inverter on/off switch
Notes to solar electronics photos
1 Wiring from solar panels
#8 Sheathed landscaping wire from junction box on roof
2 Solar input fuses and quick disconnect
Very handy when working on the system or diagnosing troubles
3 Morningstar Tristar TS45 charge controller
A 45 amp controller is a bit of overkill for a system that produces less than 20 amps, but I can use it later should I get a larger trailer with more panels. A temperature sensor wire runs to the positive battery terminal to allow the controller to adjust charging voltage as battery temperature varies from 77 degrees F. The controller charges the batteries to 14.8 volts at 77 degrees F as recommended by Trojan Battery. At temperatures lower than 77 degrees F the voltage will be higher, while at higher temperatures the voltage will be lower.
4 Shunt for Tri-metric 2025 meter
The TriMetric meter measures minute voltage drops across the shunt to derive amps going in to or out of the batteries
5 Common ground
6 Main DC fuse
7 DC distribution panel #1
This panel feeds all five DC receptacles in the cabin. It also feeds the existing DC distribution panel.
8 250 amp inverter fuse
9 Vent holes
The electronics produce a fair bit of heat. These holes were drilled through the dinette pedestal to provide ventilation. An aluminum vent cover masks the holes from the outside.
10 Samlex 1250-watt modified sine wave inverter
See charge controller note. This inverter was chosen because it does not fault until 16.5 volts. At temperatures less than 77 degrees F the charge controller will allow the voltage to exceed 14.8 volts in order to fully charge the batteries. On cold days the voltage may be 15.1 or 15.2 volts. Many inverters fault at 15 volts, thus on cold days the inverter would be unusable as the batteries approach full charge. While the inverter produces AC current just fine, the cooling fan is LOUD and runs a great deal of the time. The fan may run for several minutes after a load is removed. I’ll be replacing this inverter when I can find something better.
11 Umbilical cord to tow vehicle
12 DC distribution panel #2 and AC breakers
13 Transfer switch and battery charger switch
I opted for a manual transfer switch, which selects between the batteries [inverter] and shore power as the source of AC power for AC receptacles and the air conditioner. The air conditioner will run only from shore power. When on shore power the system will still draw from the batteries for all receptacles. This way, when we are at home we can run the air conditioner on shore power but still continue to use the solar panels to power all other AC needs. Should the solar panels not be able to meet the AC and DC needs while we are at home, the batteries may become depleted. In that case the battery charger can be turned on.
14 Shore power cable
15 Iota 30 amp battery charger
Provides 3-stage battery charging
16 AC receptacle for battery charger
17 AC receptacle
18 Converter was here; now removed
HandyBob, our installer, loathes the converters installed on older RVs because they do not properly charge the house batteries. He removed our 20-year-old converter. Since our inverter is not an inverter/charger we installed a stand-alone battery charger.
19 Bogart Engineering TriMetric 2025 meter
At any time the meter will display the number of amps going in to our out of the batteries. The meter attempts to track the state of battery charge in terms of amp-hours down from full charge. The meter will display this as amp-hours down or as % of full charge. While this measure seems to be a less-than-completely-accurate, the approximation is very handy in planning electricity usage given expected future insolation.
20 Remote inverter on/off switch
As the inverter is beneath the dinette, the remote switch allows the inverter to be conveniently switched off when not in use. The no-load draw of our inverter is .3 amps.