Choosing solar over genny..... For now

[Mr_funnypuns]

Ok, I another thread I was considering a generator for my spring camping trip to mammoth cave. I could not convince myself to consider solar. But a number of people gave very good reasons to reconsider.


So I conducted small scale experiments with a 5W amorphous panel I had on hand. I live in forest that's mostly lost its leaves, and found that the panel delivered about 2.5W in indirect sun, 5W in direct sun, and around 0.5W in the shade of a tree trunk.

I also noted that at noon there was a lot of direct sun, and that the average power output over a day with a flat panel in partial shade was around 2W x 5h = 10 Wh (about 40% if rated capacity). Most of the power was collected within local noon +/- 1 hr.

eBay gave a nice price on a 200W package that included A 40A PWM and 10 gage cable. so applying my observations, I get 200W x 40% x 5 h = 400 Wh or about 28.9 Ah at 13.8V. So enough to run my heater and a little more.

I ordered the renogy kit, and some 3M 4930 Tape for mounting.

Now I need advice. Is the renogy controller good enough? Should I get a better one?

[scrubjaysnest]

............................snip.................. .....

Now I need advice. Is the renogy controller good enough? Should I get a better one?Several questions since I am un familar with the renogy CC.
1. Does it use temperature compensation? If so is it remote or local?
Temp comp is very important and more so if the CC isn't located with the battery(s). My Morningstar uses a remote probe that connects to a battery terminal.

2. Can the CC output charge curves, voltage settings, be changed with either switches or software? This allows getting a closer match to the charge requirements that your battery manufacture prefers. In this case I'm not referring to selecting Flooded vs AGM vs Gel. The voltage selections in this case are Bulk, Absorb, and Float. Equalize is a fourth voltage that also shows up.

Bulk: this one starts out at battery and rises until the Absorb voltage setpoint is reached typically 14.4 volts.

Absorb: This is held at 14.4 to 14.8 volts in most cases and is very critical for Gels to prevent over voltage.

Float: somewhere around 13.4 volts and the CC switches to this when battery current drops to around 2 amps of after a fixed time period.


Equalize: Typical between 15.5 to 15.8 volts and is normally time fixed. Happens usually on a 28 day cycle. Purpose is to reduce stratification in Flooded batteries. A few AGM makers are starting to recommend this, I have doubts it has any value in an AGM.

[Mr_funnypuns]

1) yes both remote and local
2) voltages are slightly configurable
Sealed/flood/gel
Boost 14.2/14.4/14.6
Equalize 14.6/14.8/none 28-day cycle
Float 13.8

But boost and equalize Seem to have 120 minute timers

[tentcamper]

We started using a solar panel this year. For years we could camp in the 30-40 degree whether running the furnace for 9 hrs a day.

With solar. We still conserve our power, but now we have gone up 5 days and still had 12.4V the morning we left. With the wooded CS's we camp at we never fully charged the battery.

[scrubjaysnest]

1) yes both remote and local
2) voltages are slightly configurable
Sealed/flood/gel
Boost 14.2/14.4/14.6
Equalize 14.6/14.8/none 28-day cycle
Float 13.8

But boost and equalize Seem to have 120 minute timers
I say give it a try. Fully charge your battery(s) at some point before connecting the solar CC. After about 4 to 6 hours measure the battery voltage and specific gravity. Use this as a base line to see if the CC is correctly charging your battery(s). Set boost at the recommended value of the battery manufacture.
Connect the remote temperature probe if you have it; otherwise mount the CC as close to battery(s) as possible.
Install breakers between each solar panel and the CC; also between the CC and the battery(s). I prefer Midnight Solar breakers because they can be used like a switch to isolate the panels and CC for working on the system. Also they have a higher DC voltage rating.
Less expensive breakers are available from any auto parts store.
Any inline style fuse will work but they are a guaranteed failure area.

[rickst29]

200W is an excellent power-point for TM Solar. But the only "40A" controller on their website is a discontinued MPPT model (the old "Tracer"). And it's overkill, too. Even if you were to add another 100W, your maximum current requirement would still be less than 17A.

The 20A Tracer "BN" (newer model, better programming and build quality) can be had for about $130, with meter included.. Add on $10 for the Battery Temp Sensor (BTS) from China.

The one thing which you must make certain: The controller must be negative ground to work properly in a TM. ;)

[Mr_funnypuns]

OK, Solar panels have arrived. One correction - It's a 30A Renogy "wanderer" controller.

I also picked up a pair of Trojan T105 batteries at $110 a piece. Thought that was a great deal.

Now, Padget... any tips on setting up the T105's in the back bay of my 2720SL? You managed to shoehorn them into the space. Any mistakes I should avoid making?

[Mr_funnypuns]

Also.... what battery box is a good fit?

[Padgett]

My GC2s just fit side by side & had to cut the lower half off the vent tube on the street side. The batteries sit on top of an aluminum platform covered with an insulator Then I made a plexiglass cover to go over the batteries with grommetted holes for the two #2 cables to the disconnect box with circuit breakers, no box will fit. I added a drain tube through the floor in case.

The disconnect box and the solar controller mount near the top of the compartment over the batteries. This leaves room for a generator to sit on the curb side of the compartment.

$110 for a T-105 Trojan is a great deal. Mine came from Sams.

[Caver]

I've been using 180 watts of solar panels on my 3023 for over 10 years. I've never has a problem running out of charge but I don't usually use the furnace. My furnace draws almost 3 amps with the blower and gas solenoid engaged. You want to avoid discharging your batteries to less than 50% of their capacity to help maximize their lifetime. Without some way to measure the net AH charge state it's difficult to know how much capacity you have remaining. Fortunately the flooded lead acid batteries are very forgiving so they will be good to start with.

In the future you might consider AGM batteries. Some of the advantages are that you don't need to "water" them and they don't give off much gas. You will need to vent the flooded lead acid batteries.

Congratulations on your new solar system. We'll look forward to learning more about your experience.

Ray

[rtcassel]

Also.... what battery box is a good fit?

http://www.allbatterysalesandservice.com/browse.cfm/4,573.html

This place has boxes for side-by-side or end-to-end placement of the batteries.

[scrubjaysnest]

OK, Solar panels have arrived. One correction - It's a 30A Renogy "wanderer" controller.

I also picked up a pair of Trojan T105 batteries at $110 a piece. Thought that was a great deal.

Now, Padget... any tips on setting up the T105's in the back bay of my 2720SL? You managed to shoehorn them into the space. Any mistakes I should avoid making?
That is a good price on 105's. The weight is about the same as the Exide's we use which were $90 a piece from Tractor Supply. You get 225 Ah vs the 210 Ah we get. Also looking at the Renogy site $10 for the remote temp probe is better the $28 for the Morningstar probe I use with the TS-45 which is over kill for a CC.

Take a look at what Wayne did for mounting the solar panels and GC-2's here:
http://www.trailmanorowners.com/forum/showthread.php?t=11022&highlight=solar+panels

[Mr_funnypuns]

Using the VHB tape, did you prep the surface of the camper top prior to making the bond? I mean more than thorough cleaning? Did you clean the surface to bare metal or just adhere to the finish?

[Mr_funnypuns]

If the CC amounted in the battery compartment next to the batteries is a remote sensor still needed? It seems unneeded to me.

[Mr_funnypuns]

My GC2s just fit side by side & had to cut the lower half off the vent tube on the street side. The batteries sit on top of an aluminum platform covered with an insulator Then I made a plexiglass cover to go over the batteries with grommetted holes for the two #2 cables to the disconnect box with circuit breakers, no box will fit. I added a drain tube through the floor in case.

The disconnect box and the solar controller mount near the top of the compartment over the batteries. This leaves room for a generator to sit on the curb side of the compartment.

$110 for a T-105 Trojan is a great deal. Mine came from Sams.
Do you have a few pictures of this setup posted?

[Padgett]

Just without the cover in place.

[scrubjaysnest]

If the CC amounted in the battery compartment next to the batteries is a remote sensor still needed? It seems unneeded to me.That is what I thought until I added mine and then pulled the before and after temp and voltage readings from the CC. The air temp in the enclosure is slightly different then the battery case temp. I found this had a difference in the time to full charge and it seems we are getting a better charge.