Advice on RV Set up & Wiring?

[Sunking]

Here are the grounding specs on the inverter where it talks about a bonded neutral on mobile applications per NEC, So back to my original question, if I ground the inverter chassis to the same spot as the inverters DC negative terminal will it create ground loop & trip the GCFI? Go Power Grounding Specs.jpg

Lets straighten you out on this document. Very first paragraph tells you what you need to know. It tells you if installed in a VEHICLE you connect the Ground Stud to the vehicle frame. Period. That is all you need to know other than what size wire is required. The size of the wire depends on what the fuse size is on the battery supplying the Inverter. Example if it is a 1000 watt Inverter, you would be using a 100-amp fuse, and that requires a minimum # 6 AWG wire bonded to the frame/chassis of the RV.

The last part of the first paragraph and everything AFTER THE 1ST PARAGRAPH PERTAINS to a fixed building structure under NEC jurisdiction requiring a connection to EARTH GROUND. There is no earth ground on a vehicle, boat, plane or space craft.

[Sunking]

That's *highly* debatable..

No debate about it. A generator is required for any off-grid system for 2 very good reasons period.

1. It is the only possible way to perform a periodic Equalization charge. Now granted that can be done at home with a commercial AC power charger. For an off-grid home you have to have a genny to do that. It takes 12 to 24 hours to equalize a battery. Cannot do that with a 4 Sun Hour day.

2. For an RV or any off-grid system, life brings cloudy days, and cloudy days means no battery charging. Sometime for many days without sun. Without a genny you are SCREWED and in the DARK in cloudy spells. If it is summer time, no damn fool parks and RV in the Sun.

Bad advice again from you. 20 years and you still not know what you are doing.

[Wrybread]

2. For an RV or any off-grid system, life brings cloudy days, and cloudy days means no battery charging. Sometime for many days without sun. Without a genny you are SCREWED and in the DARK.

Sorry but that's simply not true. Not only have I never needed a gennie, but I haven't run out of power in years. And I'm in cloudy coastal Northern California! If my batteries get low no biggie, they'll be charged up the next day when the sun comes out, or soon enough. If I do happen to hit a *long* period of *absolutely no sun* when I absolutely need to use my RV, then I can go plug in somewhere, or just drive. That's never once happened, but even if Mount St. Helens erupted again it's easy enough to deal with short of lugging around a gennie.

Bad advice again from you. 20 years and you still not know what you are doing.

Ha you're funny my poor overly theory-based friend. I say the proof is in how well my systems work, but I don't expect you to understand something so practical. And something tells me you've never owned an RV. That's no biggie, but your advice to people with RVs is so overly complicated that's it's often basically just wrong. People come asking for the time and you tell them how to build a watch, and then tell them not to build a watch anyway. It would be laughable if it didn't lead to so many people either not building solar systems or over building.

Don't get me wrong, safety is massively important. But after that, if for example someone doesn't want to take your advice about using 200 watt panels instead of 300 watt panels, or they want to stick with 12 volts, or any of your other recommendations that are more like demands, you just have to learn to let it go.

[SunEagle]

That's *highly* debatable. I've never once needed a generator in my RV, and I've been at it for 20+ years. Now the first thing I do when I get a new RV is rip the gennie out. Makes a great spot for battery storage by the way.

Unless you're using an air conditioner, there's absolutely zero need for a generator in my experience, especially if you're not living in the camper. Solar is your friend, especially in an RV.

And despite the recent turn in this thread, there's no need to over complicate it. As long as you're keeping it safe of course.

Unfortunately most people (or significant others) want AC because they are too hot. So unlike you (who I admire living as basic as possible) a genny is a necessary evil and IMO can come in handy if needed when the batteries are low and you have no other way to charge them. It does happen sometimes to us less fortunate people that need creature comforts.

[Wrybread]

Unfortunately most people (or significant others) want AC because they are too hot. So unlike you (who I admire living as basic as possible) a genny is a necessary evil and IMO can come in handy if needed when the batteries are low and you have no other way to charge them. It does happen sometimes to us less fortunate people that need creature comforts.

Small point: I have creature comforts! I'm *not* living as basically as possible. As the expression goes "any fool can be uncomfortable". I'm running multiple computers pretty much all day and much of the night, a lot of lights all night, music, heat, charging lots of devices, and I even power my fridge off electricity part time. Whatever I want, I hardly give a thought to power. Just common sense simple optimizations like switching to LEDs, no microwave, no electric coffee maker. If someone needs a lot of heat consider a Buddy heater or something similar that doesn't have a heinously inefficient fan (most are around 80 watts).

And by the way I'm far from the only one who noticed that with some optimizations they don't need a generator. Most of the people I know who installed decent solar systems have ditched their gennies, or just never use the thing anymore.

Then there's no stinky, noisy and flaky generator running all the time.

And, on the subject of safety, there's nothing in the solar world that comes close to the danger of hauling around gas cans for a generator.

[Sunking]

Well Wrybread you are the only person on the planet who has never had a cloudy spell. Unfortunately for the rest of us have cloudy spells and without a genny or battery isolator are forced to shut down and wait a few days to recharge the batteries. You really expect anyone to believe your fairy tales? You gotta be pretty gullible to believe you have been doing this for 20 years and never had a cloudy spell and batteries that never get discharged to the point you went dark. Or never needed to EQ the batteries. You are are full of chit. You might fool a few folks with no knowledge of solar and batteries, but not folks in the biz, educated, with knowledge and real experience.

[J.P.M.]

And, on the subject of safety, there's nothing in the solar world that comes close to the danger of hauling around cans of gas for a generator.

I'd call the potential of getting zapped by several hundred Volts and then falling off a roof as somewhat comparable in terms of danger.

[Wrybread]

Well Wrybread you are the only person on the planet who has never had a cloudy spell. Unfortunately for the rest of us have cloudy spells and without a genny or battery isolator are forced to shut down and wait a few days to recharge the batteries. You really expect anyone to believe your fairy tales? You gotta be pretty gullible to believe you have been doing this for 20 years and never had a cloudy spell and batteries that never get discharged to the point you went dark. Or never needed to EQ the batteries. You are are full of chit. You might fool a few folks with no knowledge of solar and batteries, but not folks in the biz, educated, with knowledge and real experience.

I never said I haven't had a cloudy spell, and I never said that in 20 years that my batteries have never run low. Of course they have, especially when my batteries are at the end of their life, and especially before the era of inexpensive solar, MPPT charge controllers, cheap LEDs, and the internet. I don't miss the days of spending $450 for 75 watt panels, or having to buy LEDs in truck stops!

But I still didn't need a generator.

You talk as if we all have someone on life support in our RVs, and if there's a single outage over the course of years that person will die. It's an RV, there just isn't that kind of urgency to the situation. And if someone wants to use AC power to equalize their batteries there's usually far easier places to plug in than a generator.

Remember, we're talking about real world RV installs here, not theoretical installations. You seem to have a hard time remembering that.

I'd call the potential of getting zapped by several hundred Volts and then falling off a roof as somewhat comparable in terms of danger.

If you've got several hundred volts in an RV install, I'd say you're doing it wrong.

Falling off the roof is of course a danger, but we don't need to climb on the roof very often, while the danger from a gas can exists whenever it's around.

[sensij]

I'd call the potential of getting zapped by several hundred Volts and then falling off a roof as somewhat comparable in terms of danger.

This thread is in the "12 V Solar for RV" section of the forum, so I think the risk profile is somewhat different than for rooftop grid tie systems. I think both Sunking and Wrybread are right to point out that the stored energy, be it in gas or batteries, requires serious attention to safety.

This has all drifted quite a way from the OP's questions, though.

[Sunking]

Me thinks RV's have gas tanks.

[Wrybread]

Me thinks RV's have gas tanks.

Of course. But those are thousands of times safer than those plastic gas cans that people strap to their campers for generators.

And don't get me wrong, I'm not saying that the risk from a gas can isn't manageable, we've all carried them. But for someone who spends a good half his day talking about safety on this forum, you seem to be overlooking that massive risk pretty often, while recommending to people that they add that risk to their setups unnecessarily.

[J.P.M.]

This thread is in the "12 V Solar for RV" section of the forum, so I think the risk profile is somewhat different than for rooftop grid tie systems. I think both Sunking and Wrybread are right to point out that the stored energy, be it in gas or batteries, requires serious attention to safety.

This has all drifted quite a way from the OP's questions, though.

I'd suggest the part about "nothing in the solar world" may refer to more than 12 Volt systems.

[Wrybread]

I'd suggest the part about "nothing in the solar world" may refer to more than 12 Volt systems.

Not in an RV forum. But to be clear, I'm *NOT* talking about grid tied or large scale off-grid systems, just RV solar.

[sensij]

I never experience temps lower than 45-50 when the sun is up, It can get to 20s at night and the first 90 minutes of day break so not sure how that plays in to it (again that dang real world making problems)?
So 60 cell panels have a lower Voc rating and can handle a wider range of temperatures than 72 cells without pushing over the Max Voc of the charge controller?

Im probably looking at a morning star MPPT TS 45, do you know what their Voc max is?

Thanks for the help

Voc max of the MPPT TS 45 is 150 V. That means that you can generally get away with a string that is about 125 Voc at STC (standard conditions, as reported on the datasheet), but it depends on the actual temperatures you may see. That usually equates to 3 x 60 cell panels or 2 x 72 cell panels. In some warmer locations, a 3rd 72 cell will work, but not if you are in the 20's. You don't want to get too close to the limit... as J.P.M. has pointed out in other threads, the surface temperature of the array in the morning could actually be less than ambient temp, with open exposure to a cold night sky.

The first 90 minutes of the day is the most dangerous time for voltage damage to the CC. Full voltage is generated with only a little bit of sunlight, and that is the coldest time.

Now that is some real world information, so two 225PVw 60 cell panels would be better than 1 330PVw panel for avoiding hitting the CC Voc rating limits?

If I did 2 225W panels itd generate 37.5A and my batteries at a C/8 are 27A charge/discharge rate, so If I limited the charging amps on the controller to 30A, what would be the difference between a single 330W and 2 225W panels, just the amount of time I can supply the 30A?

Yes, with 450 W instead of 300 W, you'll be capable of generating 150% more power for every moment that you haven't maxed out at 30 A, and extending the amount of time you are capable of generating the full 30 A. I'd argue that 60 cell 260-280 W panels are the most cost effective to build around with today's panels... < 250 W panels take the same amount of space, don't really give you any more design flexibility, and aren't usually any cheaper per watt. 72 cell panels are worth considering if they fit better in the space, but usually they are more limiting for your design options.

[Carv]

Now back on Track

THANK YOU sensij for an actually answering my with some facts & logic behind it.

I can get both 250W 60s & 330W 72s for very similar prices and they take similar real estate so again it comes down to 1 330W or 2 250W panels and what the performance differences would be VS what I'd give up/have to do.

sensij in your opinion, would you say I'm better off with the 2 250W 60 cells because of the Voc limits on the CC AND the fact I'll have over capacity so if there are some inefficiencies it'll compensate for it them? (If my batteries can comfortably handle a C/5 charge rate and not the assumed C/8 (more than 30A charge) depending on what their resistance actually is, they may be able to use up to 45A charge, I'll research it and see)

Thanks