Any tips on my setup?

[-TX-]

I am not trying to get personal but it looks a little cramped.

While I am close to retirement and my wife would enjoy living (for short times) in our 36ft Class A RV it would not be something I would chose to have raised our kids in. But then again there are some people that seem to like those "little houses" that you tow around behind a truck.

To each their own if you enjoy the life style then I can't fault you on your choice.

Beats $100/night hotels every day and twice on Sundays!

20170309_090039_001.jpg

[-TX-]

> Tabs have given me a headache

Ha! Amen.

Are you using any kind of battery monitor on your system?

Not specifically, no. But I do have my inverter (and soon) controller monitoring them (mppt will also have a temp gauge), and a couple of voltmeters so I can steal an easy glance at their status constantly.

I'll need a better solution though because my inverter is hard set to issue an alarm only when voltage drops under 21v, and at 21v the things are massively depleted. I don't know what the manufacturers point was to set it so low. Deka, for example, says that their battery is 50% depleted at 24.4v. That's where an alarm should ring.

[SunEagle]

In fact here's the view as I type this from my RV:

I am not trying to get personal but it looks a little cramped.

While I am close to retirement and my wife would enjoy living (for short times) in our 36ft Class A RV it would not be something I would chose to have raised our kids in. But then again there are some people that seem to like those "little houses" that you tow around behind a truck.

To each their own if you enjoy the life style then I can't fault you on your choice.

[SunEagle]

You just agreed with my comment about the tech being immature.

The tech concerning "tracking" has improved to the point that there are more and more Utility sized solar arrays that have found a way to install their panels with at least a single axis tracker that is cost effective by producing more then the cost of maintaining the mechanical side.

For the home user a tracker is not yet economical but due to the cost of solar panels dropping it is better to just install more panels at different fixed compass points to increase the yield.

[Wrybread]

> Tabs have given me a headache

Ha! Amen.

Are you using any kind of battery monitor on your system?

[-TX-]

Tabs have given me a headache

[Wrybread]

In fact here's the view as I type this from my RV:

[-TX-]

Not really. I had a contract about 6 months ago where I saw an advantage in off-grid and went from there. It's been an experience!

12x230ah, 4S3P. I should create a post of where I'm at. lot of work.

[Wrybread]

2k, awesome! What are you doing for a battery bank?

That indeed is a massive system and I'd go 24 volt for that too.

I agree with some things Sunking said about MPPT. Don't get me wrong, I'm not advocating PWM. Where I disagree with him is a) that the Tracer 4210A controller is a POS (I don't think he's updated his thinking since the early Chinese "MPPT" controllers on ebay that were fakes; these are very well reviewed), and b) that its inadequate for my setup to the point that it justifies spending another $600+.

And is there a thread where you're discussing why you think you need 2k of panels? My RV is an office too (as well as coastal surf buggy), I run a laptop all day every day (I'm a programmer), and I'm typing on it now in fact. And I have a ton of lights and music, and I currently only have a single 300 watt panel. But I don't power my fridge or water heater off electric though, yet. And I don't watch TV or use the furnace blower often, since I've found Buddy style heaters to be great. And I don't run a desktop computer, just laptops.

[-TX-]

My RV is my office away from home.

My situation is that it could mean money, time and convenience if I could service an off-grid site in my 'office'. So for me, no matter that I have not read of a single 2k solar setup on an RV, I measured space availability for 2k of panels, then went nuts fitting them into a system that would work. So this isn't a weekender where, you're correct, 200w would suffice, mine is a different beast.

I agree with Sunking about the MPPT

[J.P.M.]

You just agreed with my comment about the tech being immature.

If that comment was directed to me: I did not and do not agree that "tech is immature". Immature is probably a poor choice to describe the evolution of science and technology or, for that matter, the acquisition of knowledge in general, in this case as it may relate to solar energy utilization. The discovery process is never ending (thank goodness), as is product improvement. The basics of the solar resource are pretty well developed. PV process improvements and improvements in batteries and support electronics will continue.

FWIW, what may look immature, to me anyway, is your level of understanding and attitude toward learning and understanding the basics. Almost like you've got a chip on your shoulder about it. Like I wrote - suit yourself, but my guess is you're not doing yourself as much good as if you'd take what's been shared here, crack a book or two, and learn some things. You've been given a lot of valuable information here from very experienced folks - for free. If you'd follow up on that and try to understand what's been presented, you'd probably do things in a more efficient way.

Good luck in your future endeavors.

[jflorey2]

from reading this forum, I see that these 900 watts of solar panels are more like 693 watts (900 * .77).

That's a reasonable normal power on a 72F day.

my panels are all permanently flat mounted, so their output is probably a lot less than that. Is there some formula for determining the output of a flat mounted solar panel? I'm in Northern California (latitude 38) if that's a factor.

Cosine of the angle between insolation and panels. At latitude 38, at the equinox, at noon, you'd be at a 38 degree angle - so that's 79% of max. That will vary about 23 degrees from there to summer or winter.

my battery bank is 4 Trojan T105s wired for 12 volt. From reading this forum, I gather that's 450 amp hours, which is 5400 watt hours.

And 2700 watt hours usable.

my charge controller is the Tracer 40 amp. I've read conflicting reports of what that amp rating means, but I think it means a maximum of 40 amps on either the PV or battery side?

Max 40 amps battery side. Input current will be the same or less.

- If I got a full 693 watts output from my charge controller, that would be 50 amps @ 14 volts. Should I worry about going that high? I'm thinking I'm not likely to get that much power from flat mounted solar panels, am I right?

The charge controller will limit its output to protect itself if your power goes that high (unlikely.)

[Wrybread]

TX, I don't know the specs of your system, but all the systems we're describing here are way overkill for most RVs. Mine (600 - 900 watts!) is absolutely absurdly over powered for an RV for example. Most RVs have 100 or 200 watts of solar with panels wired for 12 volts. If they're lucky they'll have an MPPT charge controller but that's far from a given. A few more modern ones will have 250 watts of power and an MPPT, but I've seen very few with more than that. And assuming they convert their lights to LEDs, that's fine for most RVs.

That's not to say I think 200 watts is adequate, especially now that charge controllers and panels are so cheap. And that's not to say a knowledge of the theory behind solar isn't massively valuable. But the culture on this forum is to overthink it without enough understanding of the realities of RV installs. RVs are all about compromises (in more ways than just solar of course). And a little inefficiency in a massively over spec'd system isn't a dealbreaker, especially if it saves hundreds or thousands of dollars, and keeps the system simpler. And the reason I care at all is that this kind of thinking is the opposite of empowering for people who come here wanting to build a solar system on their camper, and ultimately fewer people will build a solar system, and (from an RV'er perspective) there's more people running their noisy and stinky generators even during sunny days.

Personally I think this is the correct assumption to start with:

All I got to say about that is, if I sit myself up on my roof from 8am-9pm I'd be dead at 6pm from sun exposure. Come May, the sun is EVERYWHERE in W TX. It is brutal. If PV can't take advantage of that than we're all wasting our time until competent tech comes around.

And not Sunking's! Who actually said:

Solar is just for show and tell or for extending long stays. You still need a generator or Isolator to get charged up dry camping for extended periods.

Mind boggling.

And unfortunately he chased away the person who built the best mobile solar rig I've ever seen:

https://www.solarpaneltalk.com/filedata/fetch?id=340644&d=1484320513

[Sunking]

What is hard to believe is that my sun is downright dangerous come May, but apparently not dangerous enough to heat the same pot via PV, that if I placed on my roof its contents would boil within a (kW) hour.

edit: hyperbole alert but the point stands.
.

OK you are now comparing Apples to Oranges. That is what is throwing you off track. A solar panel transforms photons to electrons, and when it is heated up produces less power. Additionally at best when the panel is at freezing temps is only 20% efficient, and goes down as it heats up. Exact opposite of thermal radiation. Just the nature of physics. The difference between winter and summer is Sun Hours and you cannot change that. In Summer you get around 7 Sun Hours, and in winter less than 3. Watt hours = Watts x Hours. Summer you have more hours, winter much less.

[-TX-]

What is hard to believe is that my sun is downright dangerous come May, but apparently not dangerous enough to heat the same pot via PV, that if I placed on my roof its contents would boil within a (kW) hour.

edit: hyperbole alert but the point stands.
.