Four year old AGM batteries are at about half life if they have been cared for. If you are not having issues with them I would keep them. Then, when they die add to the bank when you replace them, if you find the need for a larger bank. (and have the space).

You can put the controller in the battery compartment if you have AGMs. AGMs "can" outgas in exceptional circumstances, but not normally. If you had a way to place them outside of that area that would still be preferred, but in your circumstance I'd put them in there.

Do you have a specific reason to use flexible panels? Generally, unless you have a special need you will be better off with conventional panels.

Joe, there are many choices that will work well. If you are going MPPT then looking at a true high voltage panel like the SolarWorld panels here is what I would do. The link is just an example...you can find these elsewhere.You just have to be sure that the physical size is acceptable for your mounting location.  I'd rather see you assemble quality parts on your own than use anyones "kit". The kits always seem to contain compromises, and typically have an upcharge associated with them. That is a generalization, but I find it to be almost universally true.  

For the batteries, if you have the height - which it seems you do - and the footprint space look at the Fullriver AGM L16's here. They are what I'm using in the new coach. 

There are lots of ways to do the solar controller disconnect. Take a look at my document on them here.  I've done it all the ways I describe in the document in the past. For others and myself. In this coach I have simple Blue Sea breakers. Sometimes simple is good.

Ban-Joe wrote:

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Jack, thanks. I'll take a look at those sites and see if I know enough to limit some of my choices. I'm sure I'll have plenty of questions. Do you typically buy your parts online and then get wire and fittings locally or do you order everything you need from several sources online? joe

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 It just depends. I usually had reels of wire when I was doing installs....and lots of other parts. So often I had what I needed. Now that my stock is greatly diminished I order most stuff online if I need it for the little work I currently do. I get welding wire at local welding shops - it is often cheaper. But you can order it online. There are parts sources on my website. I'm about to add a bill of materials for some of the sample systems. That will include the source.  You can get stuff lots of places, though.

I shouldn't have opened these posts this late at night. One site leads to another, to another, etc. I've never seen some of these tools. And I had to go back to researching after Jack mentioned high V panels. I just skimmed over it as I was certain I wanted the 16 to 18V panels. I see a lot of advantages with the HV, especially the price. I'll have to start writing down what I think I need for a system and all the parts involved. Thanks for all the help. joe

Jack, I may take you up on that offer but it may take me a while to get to that point. I need to identify what panels I will use before I can map this out.

I searched for some HV panels and with very few exceptions, all the panels I located (270-315W) were 69" or 79" by 39". I pulled the motorhome out of the barn and took photos of the top. I then took measurements of all obstructions. After going thru all the locations, I can place 2 panels up with one of them tight between a Fantastic fan/vent and the shower dome (39" distance between them). I may have room for a 3rd if I place it forward of the front A/C unit. I don't know about the wisdom of that far forward.

I talked to wholesalesolar today--very nice people. She said the 39" is standard width for HV panels. She had only one brand (Topoint) with a smaller footprint, 190W and 32" by 62" and rated at 24V nominal. I'll have to do some more measurements tomorrow but believe I can fit 4 but may be crowding the A/C shrouds a bit with 6" clearance. Also, how far should one keep the panels from the MH or trailer roof edge? These panels have an efficiency rating of 14 something and I have seen others that are 15 plus and 16 plus. Is this a huge difference in numbers or should I worry about that?

Final question for tonight is: whether its 24V, 30V, 35V or 45V, when wired in parallel, that higher V arrives at the controller and is reduced down to 12V or 14V, whatever the batteries call for. What happens to the excess V above the 12V or 14V? Does that affect amps or does it just dissipate?

I have photos of my project but have no clue as to how to download them onto here. Anyone with the ability to try to enlighten me would be appreciated also.

Thanks for the help

Joe

Thanks, Terry, I'll look at that but like many people my age, I'll probably have to get my granddaughter here to do it for me .

I think my vision is coming together with a workable system. Have searched locally and found a supplier for Sun World 280 mono and have 3 reserved when they come in in a couple of weeks. Panels are rated: Vmp 31.2V; Voc 39.5V; Imp 9.07A; and Isc 9.71A X 3 panels for 29.13A. These panels come with H4 connectors and internet search determined H4 connectors are compatible/intermateable with MC4 connectors. Panels are 66" by 39"; will be installed with smart feet, 3 to a side; pigtails from elec. supply are 10AWG. Homeruns to combiner box will be <7'. Purchased a combiner box, tube of 3M 5200, and weathertight entrance connectors. Elec. supply will provide hubs suitable for 10AWG and #4AWG.

Homerun to battery bay will be approx. 20'. Voltage drop calculator using copper, single conductor, #4AWG, DC current with Vmp at 31.2 and Isc 9.71 (X 3 panels) at 29.13A gives me a V drop at 18' of .83% and at 25' of 1.15%. Using these figures for #6 AWG gives a drop at 18' of 1.31% and at 25' a drop of 1.86%. I'll stay with the #4 AWG. What I don't know is the type of wire the online calculator bases its calculations on: #4 AWG black; #4 AWG black welders wire; or #4 AWG orange welders wire with finer strands. I located the #4 AWG black welders wire at a local welding supply shop for $1.04/ft. With such low V drop described above, I'm tempted to go with this wire on such a short run.

In the battery bay, incoming line will go to disconnect box (probably get Big Baby with DIN 40A breaker), on to the Tri Star MPPT60 controller, switch to #2 AWG out of the controller and through the disconnect with 60A breaker on this side, then on to the battery. Negative line will go straight to the controller, then switch to #2 to the battery. Battery is already wired to the factory installed Xantrex RV 2012 inverter/charger. Xantrex manual calls for run under 5' with 2/0 but factory wired with 4/0 with 300A fuse inline to inverter. V drop calculations from controller to battery at 4', 14.3V and current at 60A gives a drop using #4 of .84% and using #2 a drop of .52%. I'll use the #2 on the short run. A Trimetric 2030A battery monitor will be installed and monitor pulled to front of coach monitor panel. What I haven't decided is whether I need a remote monitor for the Tri Star controller or if the Trimetric will suffice for my purposes.

The local battery store will get me the Fullriver AGMs DC 400-6 at $455 each for an 800AH bank; he also suggested the DC 335-6 at $325 each for a 670AH bank. I'll probably go with the 335s since our usage is 100 to 125 AH daily and 800 AH is more than I need. The Xantrex manual also encourages usage of the same size wire for battery connections (ie. 4/0) as used from battery to inverter.

This is what I have so far. I'll be out of town for 4 days of each of the next two weeks so will start this project after that. Any comments, suggestions, or corrections on above would be appreciated.

Joe

-- Edited by Ban-Joe on Monday 22nd of September 2014 10:37:57 PM

bjoyce wrote:

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You will have to have a PC with a serial cable (USB to serial) to program the Tri Star for your AGM batteries. AM Solar keeps one Windows laptop for this purpose, otherwise they use Macs.

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 Or set up an ethernet connection from the controller to your router. In any case you have to customize the programming. You will want to get the settings just right. If you do set up a PC connection then you don't "have" to have a remote panel. You can look at everything on your PC on your wireless network.

On the wire question - you can use any of the wire types quoted. So I'd use the locally available stuff.

On the battery interconnects - yes use the same size cable for the interconnects as the inverter lines.

Other than that, it looks like you have it nailed.  See, it is not that hard.....  :)

 

-- Edited by Jack Mayer on Tuesday 23rd of September 2014 09:04:13 AM