New to solar. questions on fuses, breakers, and grounding

[Amy@altE]

Ground fault breakers are intended more for buildings than vehicles, you don't need one. You could look at using a Midnite Solar SPD for lightning protection. Although nothing will protect against a direct hit, it is good protection against a nearby hit. http://www.midnitesolar.com/productP...tOrder=1&act=p

[njp6x6]

Thank you for the information, I have a few more questions. The breakers that you provided the link to are not ground fault protection beakers. The ones you suggested are 12.50 apiece and the ground fault breakers are 89.00 apiece. So my understanding is that you don't think the ground fault breakers are necessary. Is that correct? One thing I should note is that I have built a small shed or "doghouse" that is well ventilated and 4'x4' to house all my components. My reasoning for this is that I expect these components will generate heat and my trailers will already be hot in the summer. Also, where I will be living is on a high plateau with absolutely no trees within a few miles so I think lighting strikes are a very real concern and I will often be traveling for a few days at a time and away from my trailer. I figure by keeping the system away from the trailer, if a lighting strike catches the whole thing on fire, at least it wont take my trailer with it. If I were to ground my components to the frame of my trailer would it then make the it more likely to have a catastrophe on my hands in the event of a direct lighting strike? Like I said in my original post, the reason I am asking about ground fault breakers and the grounding rod is because that what is shown in the CC manual but I assume they have to in order to be meet NEC standards. Also, you suggest using a 4AWG wire from the Battery to the inverter but the inverter calls for a 150 amp slow blow fuse which based upon the ampacity charts I have seen would require a 2/0 wire gauge? I should also point out that I wont be exceeding 200 watts of panels this summer but I would like to size all my breakers and wire so that I can grow to 400 or 500 watts in the future. Thank you for your help here

[Raj]

Hi njp6x6,

Most small RV type solar power systems require a chases ground, not a ground rod. Check the literature for your inverter for grounding requirements. 500 watts would be about the max amps that your controller can handle, but the PV panel wattage needs to balanced with the size of the battery bank.

Example: PV is 400 watts divide by 12V (battery voltage) equal 33 amps. So FLA (flooded lead acid) batteries need about a 10 percent charge rate so 33 divided by .1 (10%) = 330 amp hour battery bank at 12 volts. If using AGM batteries you can use a 15% charge rate. In this case 220 amp hour. However battery bank size is really determined by your power use as loads in kilowatt hours. Then size PV accordingly.

PV panels need to be fused if you have more than 2 in parallel. Breakers are better for PV to CC and CC to battery and also battery to inverter because they can be used as switches for maintenance and emergency shutoff.

The shunt is just a resistor that can be used to get a very accurate measurement of battery voltage and amps used.

This enclosure ...http://www.solar-electric.com/instal...nedc-quad.html

With this type breaker ...http://www.solar-electric.com/instal...amodccibr.html

These would work well on a small system. Size your wiring to amperage. Probably AWG #6 in this case and AWG #4 from battery to inverter.

Good luck

Rick

[njp6x6]

As I stated in the title I am new to solar energy systems. I have several questions regarding circuit protections. I will be living out of small travel trailer for the summer and as of now I have a single 100 watt panel, a Xantrex C40 (40 amp) charge controller, and a 1000 watt power inverter. I don't anticipate every going over 500 watts of panels. This will be a 12 volt system. Most videos i have watched don't talk about fuses or grounding on small scale systems like this. I planned on placing appropriately sized fuses between the panel and the controller, controller and batteries, and between the batteries and inverter. However, the instructions that came with the charge controller show a ground fault protection breaker and something called a shunt between the controller and the batteries. Is that necessary or do they just have to put that in the instructions because ground fault protection is required by electrical code? ( These breakers cost about 10x more than a fuse) What is the purpose of this shunt and is it necessary? And lastly, do i need to drive a 8 foot long ground rod to ground the panel, controller, and inverter? I am thinking the answer is yes on the grounding question. Thank you in advance for any help