RV system design questions?

[PNW_Steve]

Hey Everyone,

I am engaged in high intensity circular logic (tail chasing) trying to nail down the details on the solar system for my RV.

I did my load calculations and found that I do not have enough space or budget to be completely sufficient with solar. I will have generator backup. So, I plan on installing the most capacity that space & budget permit. I do hope that, with some lifestyle modifications, I can minimize generator run.

I do NOT have the option of tilting my panels so I intend to overpanel a bit. I also spend part of the Winter in Seattle.


Here is my tentative plan:


6 x Sparkfun SMX260 panels (1560 watts)
Watts (STC), W 260
Maximum Power (Vmp) 30.7 V
Maximum Current (Imp) 8.47 A
Open Circuit Voltage (Voc) 37.9 V
Short Circuit Current (Isc) 8.98 A

1 x Midnght Classic OR Morningstar TS-45 MPPT charge controller

4 x L-16 Batteries 6V-370A/H OR 8 x GC2 Batteries 6V-215A/H wired for 24V

1 x Xantrex Prosine 1800 Inverter (24v)

1 x Trimetric TM-2030 Battery Monitor

1 x Battery charger - Suggestions??


Questions:

Do you see any glaring issues with my selection?

Can you make recommendations regarding charge controller choice?

Can you make recommendations regarding charger selection. I have heard mixed reviews on the Iota and not much else.

I know somebody is going to mention that I am looking at hanging 1500w of panels on a system that can only utilize 1000w. Answer: Seattle in December.

Any input is appreciated.

S.

[Mike90250]

save the $ and skip the trimetric, you will be using a plain volt meter most of the time, a nice analog meter should do the job well

The classic has a pretty noisy fan, if you will share cabin space with it, in daytime, it will drive you mad.

The morningstar TS MPPT 60, has a ethernet interface and web server, so you can hook it up to a computer or wifi router and monitor via the web, and skip it's $100 digital meter . The 45A version does not have web interface

Either controller will need a location with good airflow, in a closet will not work.

40A charging at 28V is 1200w, so that is pushing the limits for a plug in charger. Xantrex should have an inverter/charger you can wire into your generator.

Panels 2s3p would require a combiner box, 3s2p needs no combiner, but you loose the flexibility to trouble shoot by comparing strings. And you may need to worry about over voltage in really cold areas if you travel much in the frosty regions

[LETitROLL]

Seattle in December, you should not plan on being able to generate more than 10% of your nameplate wattage on cloudy days, especially if your panels are not perfectly tilted. Not sure what your budget is but if its tight take a look at the Victron MPPT controllers, slightly cheaper than the others, and easy to hook to a laptop or smartphone for monitoring and adjusting, very good reputation overall, and their tech's and engineers are very familiar with cloudy places, suppose to have some of the better/faster software for getting whatever crappy maximum harvest you will get in cloudy places.

[PNW_Steve]

Thanks for the info.

In no particular order:

Sounds like a 40A shore charger is a non starter. For this application what charger would you recommend with an eye on budget?

I already have the Xantrex inverter and the battery monitor.

I am not finding much information on the Victron. Does it support current limiting and battery temperature compensation?

My batteries will be in an outside storage bay.

Thanks again.

S.

[PNW_Steve]

Now I have another question:

I have been reading and reading trying to educate myself.

I have read in a number of places that I should limit my charge rate to 10%-13% of the banks C20 rate. Example: if I run with the L16s then I would want 37A max charge.

I just stumbled across a thread directing a poster to bulk charge L16's at 30% of C20.

Now I am confused......

[LETitROLL]

Thanks for the info.

In no particular order:

Sounds like a 40A shore charger is a non starter. For this application what charger would you recommend with an eye on budget?

I already have the Xantrex inverter and the battery monitor.

I am not finding much information on the Victron. Does it support current limiting and battery temperature compensation?

My batteries will be in an outside storage bay.

Thanks again.

S.

I have a 15A victron and it is very adjustable, i have it hooked to my laptop, it has all that and lots more, including harvest data, etc.
Here is a link to the MFG. page for the size of controller(s) you would be looking at

https://www.victronenergy.com/upload/documents/Datasheet-BlueSolar-charge-controller-MPPT-150-45-up-to-150-100-EN.pdf

[PNW_Steve]

I have a 15A victron and it is very adjustable, i have it hooked to my laptop, it has all that and lots more, including harvest data, etc.
Here is a link to the MFG. page for the size of controller(s) you would be looking at
https://www.victronenergy.com/upload...150-100-EN.pdf

Thanks for the recommendation. I am eyeballing the 150/45 or 150/70.

I am hoping to get some charger recommendations as well if anyone has a thought.

Thanks again.

S.

[PNW_Steve]

Any thoughts on this one? https://www.batterystuff.com/power-s...YaAr8HEALw_wcB

[Mike90250]

Any thoughts on this one? batterystuff.com/power-supplies/load-bearing-chargers/power-max/power-max-pm3-30-24

Looks plenty beefy. 85%eff and no PF listed

[PNW_Steve]

Looks plenty beefy. 85%eff and no PF listed

Thank you for the reply. Beefy is a good thing. I am also concerned whether or not it will do a good job of charging my batteries properly.

I started out looking at 24v RV converter/chargers. Then I came across complaints about them not charging "properly". Finally, I read the sticky here about avoiding "automotive" chargers.

I find myself without enough product knowledge to make a confident choice.

I have settled on 4 x L-16 batteries for a 24v - 370AH bank.

Charger recommendations would be much appreciated.

[Mike90250]

If you have unlimited shore power, it will charge batteries fine. If you are hooked up for days at a time, it may overcharge a bit, depends on the quality and precision of the internal voltage calibrations.

[PNW_Steve]

If you have unlimited shore power, it will charge batteries fine. If you are hooked up for days at a time, it may overcharge a bit, depends on the quality and precision of the internal voltage calibrations.

Thank you for the reply. Do you have any suggestions regarding a charger choice? I want to take good care of my batteries.

[Mike90250]

do you want the charger to be a plug it in and forget about it, or will you monitor it and check / disconnect it every 24 hours ?? The more work you can do, the less smart the charger.

The charger should be at least 10% of the battery bank ah, so if you had a 370ah battery, you need a 35A charger.

[PNW_Steve]

do you want the charger to be a plug it in and forget about it, or will you monitor it and check / disconnect it every 24 hours ?? The more work you can do, the less smart the charger.

The charger should be at least 10% of the battery bank ah, so if you had a 370ah battery, you need a 35A charger.

My preference is for one that is completely automatic.

[Mike90250]

I'm familiar with the Genius series of chargers, they remember the last setting you had, after a power failure. i use one myself. Amazon carry them.