Solar Set up

[byrdz1]

The curves above provide some insight. Let's say a panel or panels in parallel puts out 12 volts. With any controller you get little to nothing into your batteries. If you put them in series you'll get 24 volts. If you use a std controller you get a bit more than half of the voltage/current into your batteries because anything over 14 or so volts is wasted. If you use an MPPT controller it will convert all the voltage/current to a charging voltage (very little loss) and you'll get 24/14 or 58% more juice into your batteries.

At that percentage increase it gets closer to "cost effective" and you get much better performance in low light.

Of course all of this is "theory" but I think that empirical experience will prove it to be in the right direction.

Cheers,

Gus

Oh dear, my head just exploded. Does that mean that I am not going to get ANYTHING through the controller to the battery? "Let's say a panel or panels in parallel puts out 12 volts. With any controller you get little to nothing into your batteries"?


I have to go sit in a corner, rock and suck my thumb now.......

[bdosborn]

Oh dear, my head just exploded. Does that mean that I am not going to get ANYTHING through the controller to the battery? "Let's say a panel or panels in parallel puts out 12 volts. With any controller you get little to nothing into your batteries"?

I have to go sit in a corner, rock and suck my thumb now.......

You're fine. Just install the panel and park in the sun. The panel will do a great job of charging the battery.
Bruce

[bdosborn]

The curves above provide some insight. Let's say a panel or panels in parallel puts out 12 volts. With any controller you get little to nothing into your batteries. If you put them in series you'll get 24 volts. If you use a std controller you get a bit more than half of the voltage/current into your batteries because anything over 14 or so volts is wasted. If you use an MPPT controller it will convert all the voltage/current to a charging voltage (very little loss) and you'll get 24/14 or 58% more juice into your batteries.

At that percentage increase it gets closer to "cost effective" and you get much better performance in low light.

Of course all of this is "theory" but I think that empirical experience will prove it to be in the right direction.

Nope, it doesn't work that way. Its like I suggested, a panel at 9-11V isn't putting out any *usable* current so it doesn't matter if its at 12V or 24V.

Excerpt form a John Wiles article (the PV Guru)

Open-circuit voltage is only slightly influenced by
irradiance. Obviously, in total darkness, the voltage output is
zero. However, even in dim light (dusk, dawn, heavy clouds)
the open-circuit voltage is very nearly the STC rated value.
Direct sunlight does not have to be shining on the module
for voltage to be on the output terminals. Current may be
extremely low, but nearly full voltage can be expected in dim
light. Thin film modules may have different characteristics,
and the module manufacturer should be contacted for
details.

Here's the entire article:
Solar Linky

John Wiles is well respected in the PV community and publishes a lot of good articles. He even answers emails if you have an interesting enough question.

I also posted it on the NAWS solar forum and they had a similar response.

NAWS Solar Forum Linky

The series approach is an interesting idea but ultimately won't help low light performance.

Bruce

[byrdz1]

Thank you. I am treating this like a paper bag that I am breathing in

the parts start showing up in the next couple of days. With any luck I have everything by the time I leave for IRG.

My next idea is to use a TV tray like device and move the solar panel from propped against the tray with the controller and battery tender underneath, from propped against the side to the top, to the other side as the sun moves.

My thinking is that I can keep the "tender bits" out of the weather under the tray and move the PV panel as the sun moves.

feedback?

[bdosborn]

My next idea is to use a TV tray like device and move the solar panel from propped against the tray with the controller and battery tender underneath, from propped against the side to the top, to the other side as the sun moves.

It looks like your battery is mounted on the tongue, is there any reason you wouldn't want to put the controller at the battery? Also, the battery tender can be connected to any 12V circuit, why not tuck it away in the trailer where there is an accessible 120V outlet and a 12V connection?

Bruce

[byrdz1]

Just as a note I have a battery tender already in the trailer in the "fuse box" area where the 110 comes in and all the power for the trailer comes into the fuses.

I am "assuming" (I know!) that the new battery tender has to go between the controller and the battery. So:

Pannel to contoller (in battery box if I can get it to fit)
controller to battery tender
battery tender to battery with alligator clips
or
Battery tender to 12 volt outlet with a male cigarette connection
I have the stuff for both connections
I end up with two battery tenders one for the solar and one in the trailer itself

[bdosborn]

You don't need another battery tender if you already have one in the trailer. The controller and the tender play well together; you can plug in the trailer when it's in full sun and the controller and the battery tenders will adjust to each other automatically.

Bruce

[byrdz1]

The stuff started to come in last night.
The battery tender has to go back it has a 110 plug in, so I must have bought the wrong thing
The panel is GI-NORM-US. Oh sure, I "knew" how big it was, but holding up my arms like "a fish this big" is different that having the sucker in the living room.

I am a little confused about the battery tender. I see that I dont' need another one, but if I am planning on hooking up like:

Pannel to controller, controller to battery with alligator clips, how will the battery tender inside the trailer be able to stop the battery from getting too much from the solar?

Don't I need the extra battery tender to take care of the directly attached solar controller?

I do understand what types of ring terminals I need now though, so I don't have to make my own cables.

[bdosborn]

Pannel to controller, controller to battery with alligator clips, how will the battery tender inside the trailer be able to stop the battery from getting too much from the solar?

Both the solar controller and the battery tender charge the battery based on the voltage at the battery terminals. Each device only supply's enough current to raise the battery voltage to a set level between 14.4 and 13.3V, depending on the charge level of the battery. Basically, both devices are charging at the same time but they won't overcharge the battery. There's some research showing that solar controllers can extend battery life due to how they supply current but the battery tender is a quality charger and you can't go wrong with either approach.

Bruce

[byrdz1]

Got it all set up and took it to IRG.

Well... it was like taking a Bazooka to a knife fight. I wasn't running much, but boy did that sucker want to put out. I could have charged half the campers, I should have taken it down to the guy that was running the genny every morning.

All I need to do now is make a case for it so it is protected, and figure out a stand. Thanks so much all!

[Maureenm]

I made a stand out of PVC pipe-pretty low tech, but it holds my panels at a 45 degree angle.

[bdosborn]

You might be able to just use a prop instead of a stand:



So where are the photos of your setup?

Bruce

[Shadow Catcher]

I am forced to admit I have not entirely figured out how to use the Victron in all its features and I don't have the computer interface link yet. being able to just glance at it and see SOC was to put it mildly reassuring. I had the controller fail on us a week prior to the trip and the replacement arrived a couple of days before we left. The defective controller went back to Morningstar the day before we left and I was in contact with them and had the replacement shipped to my daughter. They did replace it after figuring out it was dead, but I had purchased the replacement to make sure we had it in time. I discovered the problem during the reinstall after the trailer was repairs from the accident. I there fore now had a brand new Morningstar SunSaver MPPT new in an unopened box I am trying to figure out what to do with.
There was a bunch of things that were more or less finished when we left and learning all of the features of the Vicron was not one of them. Oh and a big hint when you take a VOM to find problems make sure the battery in it is not dead.

[Shadow Catcher]

I am forced to admit I have not entirely figured out how to use the Victron in all its features and I don't have the computer interface link yet. being able to just glance at it and see SOC was to put it mildly reassuring. I had the controller fail on us a week prior to the trip and the replacement arrived a couple of days before we left. The defective controller went back to Morningstar the day before we left and I was in contact with them and had the replacement shipped to my daughter. They did replace it after figuring out it was dead, but I had purchased the replacement to make sure we had it in time. I discovered the problem during the reinstall after the trailer was repairs from the accident. I there fore now had a brand new Morningstar SunSaver MPPT new in an unopened box I am trying to figure out what to do with.
There was a bunch of things that were more or less finished when we left and learning all of the features of the Vicron was not one of them. Oh and a big hint when you take a VOM to find problems make sure the battery in it is not dead.

[byrdz1]

I will take some pics next weekend and post. I have seen some pretty nifty pvc setups, but I like the prop because it would be small. I also like the handle. Chuck tarted his pannel up with two pieces of plywood, hinged, so that it foldes over the pannel when stored, but articulates back to hold the pannel at whatever angle he sets the plywood to when folded back, very useful.