2020 Cherokee Grey Wolf 26DBH

[TexasRalph]

Has a solar panel on the roof. How does it work? Switch? ????

[NavyLCDR]

Originally Posted by TexasRalph

Has a solar panel on the roof. How does it work? Switch? ????

I would imagine it produces 12V DC. So it will provide power to the 12V DC loads such as lighting and water pump. Any extra DC power not being used by the loads will be used to charge your batteries.

[bikendan]

Originally Posted by NavyLCDR

I would imagine it produces 12V DC. So it will provide power to the 12V DC loads such as lighting and water pump. Any extra DC power not being used by the loads will be used to charge your batteries.

Solar does NOT power anything. It recharges the batteries which power things. Solar does not directly power the lights or the water pump.

[NavyLCDR]

Originally Posted by bikendan

Solar does NOT power anything. It recharges the batteries which power things. Solar does not directly power the lights or the water pump.

So, it is not connected directly to the 12V bus then? How can it be connected to the batteries only to charge them and not be connected to the rest of the 12v electrical bus? In order for the solar panels to only charge the batteries and nothing else, they would have to be connected to the batteries only, and the batteries would have to be completely isolated from the 12v bus of the RV. When the solar panels are connected to the batteries only to charge them, then what powers the rest of the 12v loads in the RV?

The basics of a 12v bus with 2 sources of power, solar panels + batteries are:
1. If the loads connected to the 12v bus such as lights, TV, etc exceed the capacity of the solar panels, then power will be drawn from both the solar panels and the battery, and the battery will eventually discharge.

2. If the loads connected to the 12v bus are less then that capacity of the solar panels, then the solar panels will charge the battery at a rate equal to the capacity of the solar panels minus the loads connected to the 12v bus.

If you have 200 watt solar panels, that will provide just over 14 amps at 14 volts. Let's say you have 10 amps of loads in the RV due to lights, TV, etc. That only leaves 4 amps from the solar panels to charge the battery. The less loads you have on the 12v bus (by turning off lights and fans) the faster your battery will charge. Turn on enough loads in the RV to exceed the capacity of the solar panels, and you will be discharging the battery, even with the solar panels connected in full daylight.

[pgandw]

A single solar panel is at most 100W. The output in bright sun will not be any higher than 5-6 amps, and probably in the 3-4 amp vicinity most of the time when there is sun.

There needs to be a solar controller that regulates the voltage going from the solar panel to the batteries. If it's a small (10W or less) solar panel, a controller is not needed. The small amount of power without voltage regulation will not damage the battery.

To NavyLCDR's point, the solar controller is normally wired directly to the batteries so that they can receive charging current regardless of whether the batteries are on the 12V bus or not.

If the batteries are connected to the bus (normal camping and trailering configuration), the charging voltage of the controller is higher than the actual battery voltage, and therefore the converter will both feed the 12V load, and recharge the batteries. The current being drawn by 12V loads will limit how much is available to recharge the batteries.

With only a single panel, wire size from the panel to the battery will usually be adequate. Once you get more than one panel, the higher current causes voltage drop with inadequate wiring and your battery recharging will be diminished.

hope this helps
Fred W