Floating ground for solar system on camper with inverter
suncamper2001 Registered Users Posts: 1 ✭
I am setting up a 12V solar system for my small fiberglass trailer camper and I have some questions for the experts here.
The battery system is 2x 6V golf cart batteries in series. The solar panel is 2 x 100Watt in parallel (each panel is fused) connected to a pwm charge controller. Eventually I might get a MPPT controller and connect the panels in series. 10AWG wire is used in the run between the batteries, the charge controller and panels.
- A shunt connected to two digital current meters that track total power will be used to keep track of total battery charge and discharge to prevent excess discharging of the batteries
- An inverter will be used to run a $60 mini refrigerator. Inverter is a tripplite PINV1500. A relay connected to a refrigerator temperature sensor will be used to cut power to the inverter when cooling is not required to eliminate power consumption from the inverter during idle. A manual override will be used to allow occasional charging of laptops and use of a very small instapot.
- wiring from battery to inverter will be 2/0 wire
- Other loads on the battery will all be DC - lights, vent fan and usb chargers
- Trailer will never be connected to AC power at campsites. Only time AC will be used is at home via an extension cord to get the refrigerator cooled before the trip starts. This will be done by unplugging from the inverter and connecting to the extension cord.
- Fuses will series circuit breakers and battery post mounted fuses from Blue Sea
- Two 150A Busses from Blue Sea will be used as +ve and -ve bus.
- Inverter, fuse boxes, charge controller, all circuit breakers will be mounted on a sheet of plywood which would then be mounted to the fiberglass
I have decided to wire the system as a floating ground because of the shunts. I didn't choose to ground to the trailer chassis because that provides an additional path for current back to the battery via the trailer chassis potentially causing the shunt readings to be wrong.
Because of the floating ground, the battery I plan to fuse both ends of the battery.
My initial wiring plan is this:
a) Battery +ve => 150A fuse on terminal => +v bus
b) Battery -ve => 150A fuse on terminal => shunt => -ve bus
c) +ve bus => 30A circuit breaker => Charge controller (CC) +ve
d) -ve bus => CC -ve
e) +ve bus => inverter +ve
f) -ve bus => inverter -ve
g) +ve bus => fuse box => various DC runs (lights, fans etc.)
h) -ve bus => fuse box => various DC runs (lights, fans etc. )
1) If i put a 150A fuse between the two 6V batteries can I eliminate the need for the 150A fuses at the battery terminals (a & b above)
2) Do I need to bring my CC connection to the battery or can i leave it as is (c & d above). I can change it if required, just need to return the single fuse holders and get double fuse holders and possibly a second shunt.
3) My inverter has a ground connection, however as stated above I was planning to use a floating ground so connecting ground connection to the trailer chassis will defeat the floating ground. Also the ground connector in the inverter is connected to the -ve terminal as well as the neutral of the two AC outlets in the front of the inverter. So looks like even without the ground connection, the inverter will be grounded to the -ve side of the battery. Will there be a risk of shock without the ground connection? Inverter doesn't have GFCI outlets, should I connect GFCI outlets to the inverter outlets?
Thank you for reading through the long post. Looking forward to your feedback.
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