Please help me with solar setup

[smyke]

I have been reading a lot about solar on here and finally decided to take the plunge or come to the dark side as some would say. Sunny side makes more sense, but whatever. 🙂

We do not use a lot of juice while camping. I currently have 2 6V GC batteries from Sam's Club. I believe about 225ah. All lights in the trailer have been changed to LED. During a long weekend (F to M) we typically use about 30 to 40% of the battery according to my voltmeter. And thats without really trying to conserve.

Once a year we go away for a full week so first and foremost I want to keep the batteries topped off so we dont have to worry about running out of juice.
Sometimes I think being able to run things on 120V would be convenient so the 1000W or so inverter may not be out of the question.

I dont want to spend a ton of money (obviously) and have found these components to be within my budget:
Tracer 2210RN MPPT Controler
MT-5 LCD Display
150W 12V Solar Cynergy Panel
or
240W 24V Solar Cynergy Panel

From the reviews and info on this fine forum these seem to be OK quality and I believe that they would do the trick for me.

I realize that controler may be a bit overkill for 12V panels but for that kind of money I figure to get something better than a regular PWM. Obviously it would be needed with the 24V panel.
And here is my question (finally):
Which would be better? 2x12V or 1x24v? Size would not be a problem.

Any and all help will be greatly appreciated.

[smyke]

Still not settled on the controller but will be ordering 2 120W poly panels from SolarBlvd now that they are available.

[Fisherguy]

Great thread for anyone thinking of adding solar to their RV, going to read through it again.
Smyke, did you figure out what you're going to do yet?

[JiminDenver]

kje wrote:

JiminDenver wrote:
You can go up to a 250w poly or a 275w mono panel. Those are going to get you in the 17-19a range. I suggest the 250w poly as it is close to the same in bright light and better in lower light.

Generally it is cheaper per watt to get 24v panels than 12v as long as both fit on the roof.

Is 250w poly the limit of what the Eco-Worthy controller can take?

If 24v panels are cheaper per watt, what are the downside with 24v panel except the size and space?

The 250w polys and 275w mono's are 5 ft panels with Voc's in the mid 30s. Larger than that and you break into the 6 ft panels with Voc's in the 40's that may be under the Voc limit of the Eco-worthy until you get a really cold day.

[pianotuna]

The down side is minor but costs your pocket book more. You needs must use an MPPT charge controller.

kje wrote:
If 24v panels are cheaper per watt, what are the downside with 24v panel except the size and space?

[kje]

JiminDenver wrote:
You can go up to a 250w poly or a 275w mono panel. Those are going to get you in the 17-19a range. I suggest the 250w poly as it is close to the same in bright light and better in lower light.

Generally it is cheaper per watt to get 24v panels than 12v as long as both fit on the roof.

Is 250w poly the limit of what the Eco-Worthy controller can take?

If 24v panels are cheaper per watt, what are the downside with 24v panel except the size and space?

[JiminDenver]

pianotuna wrote:
Hi Jim,

I think you mean diversion load.

JiminDenver wrote:
Some controllers can do a diversified load, meaning the once the bank is in float the controller will turn on a load that will use the excess somehow, but again most are limited in the current available.

Thanks Don. I really should look at what the phone is doing more often. lol

[BFL13]

jrnymn7 wrote:
Jim,

Do you run the trailer loads off the bank, or off the controller's load output?

thanxx!

Even when you use the load terminals, you are "off the bank" for the power.

The load terminals are only useful in that they have their own controller settings for on and off so you can't run the battery down, etc.

All controllers will let you run loads when not using the load terminals up to what the solar panel can deliver including whatever the battery wants. If the solar can do 10a at the time, and the battery wants 3a, then you can run a 7a load without taking anything from the battery's 3a. So recharge your laptop in the afternoon.

[pianotuna]

Hi Jim,

I think you mean diversion load.

JiminDenver wrote:
Some controllers can do a diversified load, meaning the once the bank is in float the controller will turn on a load that will use the excess somehow, but again most are limited in the current available.

[JiminDenver]

Load terminals are usually meant for a light or other small load. They are usually limited in what they can power. Some controllers can do a diversified load, meaning the once the bank is in float the controller will turn on a load that will use the excess somehow, but again most are limited in the current available.

My window shaker is rated for 446w on high. It starts low but climbs as the pressure builds. The highest I have seen is 450w.

[jrnymn7]

o.k., thanxx! I figured as much, but thought I'd ask. I'm guessing most folks don't use the load terminals, except for maybe an outdoor security light?

I have a 5000btu window shaker I'd like to make more use of. Maybe with solar I'll be able to use it in short spurts, if things get too muggy. It pulls ~430w once up and running.

[JiminDenver]

jrnymn7 wrote:
Jim,

Do you run the trailer loads off the bank, or off the controller's load output?

thanxx!

Our first trip with the 230w panel and Eco-w I was trying to get the controller into bulk and see what it could do up there at mid day. No inverter to pull it down so I turned on both exhaust fans, controller jumped to 4a and the battery stayed in float. I added all 17 of the LED lights, battery stayed in float. Added the furnace fan and the controller put out 11a, battery stayed in float.

Finally I found a 12, 200w coffee pot buried in the storage, took the solar offline until the pot dropped the battery to 13.4v and brought the solar back online. The solar jumped into bulk at 16a, the pot ran like it has never done before and the battery sat at 13.4v. That's when I knew it wasn't just a battery charger, it was a micro generator too.

The next year I went with two 245w panels, the inverter, bigger bank and played with the toys. The panels couldn't run a microwave pulling 1375w alone but the difference in the voltage under load fell much slower than with out the solar. In fact we could run the microwave for 10 minutes before the voltage hit 12v, only a few minutes were possible without the solar. Things like the auto drip and hair dryer never got the voltage low but they don't run that long either.

The three 250w system is designed around the ability to run the 5000 BTU air conditioner off of the panels after the bank helps with the start up surge. Two panels can't do it but it took running it for four hours with the compressor always on to get the voltage under load to 12v. The third panel will add another 17a and that will run the unit on it's own. So most of the time the batteries will be in float unless we run a load too big for the system to cover or it's too dark for it to produce.

[pianotuna]

Hi,

You could service up to 400 amp-hours of battery bank.

kje wrote:
How big battery bank is appropriate with a 250w poly and the 20A Eco-Worthy controller?

[jrnymn7]

Jim,

Do you run the trailer loads off the bank, or off the controller's load output?

thanxx!

[JiminDenver]

I used a grp 27 95 Ah FLA with the Eco-w and a single panel, it loved it. Float came early and then the panel ran the trailer the rest of the day. By nightfall the battery was as well charged as it was going to get and even after running the furnace all night, the resting voltage the next morning was 12.57v. That's not very depleted so once again float comes early.