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Author Topic: disconnects and fusing for small Solar system  (Read 1333 times)

blw2

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disconnects and fusing for small Solar system
« on: April 16, 2019, 04:00:32 PM »
I'm thinking through a small solar set up, just 100 watts to keep things topped off in storage...but I figure i'll prob set it up for future expansion... no more than 200-300 watts total...but all of that is just a big maybe.  I currently don't have an inverter and we don't boondock nearly as much as I'd like to

Anyway
most of the kits I'm looking at don't include fusing of any sort..and some of what I'm reading indicates that it's not really needed.
Also, I'm not seeing much of anything regarding disconnects in the system.
Seems to me though that disconnecting might be "good practice" if nothing else.... the question though if I do...do I out the disconnect switch between the panels and the controller, or between the controller and battery?
ditto fuses?

Right now I'm leaning to put everything under the bed, where my converter and all the current electrical stuff is.  The output side of the controller to the battery can land on the battery side of the "use/store" disconnect solenoid.....
   although that concerns me slightly since I don't know for certain what parasites are tapped in between there and the battery.
There's a reasonably short drop from a panel location to this area, and everything is accessible and easy.  Down side is a long run from there to the actual battery with existing (i.e. unknown length and condition) wiring ... 6 Ga according to the schematics I have from Thor

Anyway, I'm curious about your experiences and ideas about setting up such a thing....

thanks
Brad (DW + 3 kids)
13 Thor Chateau 31L Class C on Ford E-450
'06 Silverado
'05 Rockwood Freedom 1910 (5-1/2 years)
former tent campers

solarman

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Re: disconnects and fusing for small Solar system
« Reply #1 on: April 16, 2019, 05:27:43 PM »

I would suggest at a minimum you fuse both the panel and battery circuits.

either fixed fuses or re-settable breakers such as these..https://www.bluesea.com/products/category/14/26/Circuit_Breakers/Push_Button_Reset-Only

KZ MXT20 480 W solar
ORV 24RKS 960 Watts solar
48V LFP, 2000W inverter/charger
Ram 2500 CTD

Frank B

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Re: disconnects and fusing for small Solar system
« Reply #2 on: June 04, 2019, 04:23:17 PM »
Still catching up on forum posts, so you may have made a decision on this already. However....

Solarman gives some excellent suggestions on fusing.

Kevin Means is the person that I followed when installing my solar system. He installed, and therefore I also installed, a disconnect switch between my solar panels and the solar controller. In retrospect, I probably didn't need it, but I'm still glad that I put it there. In my case, it protected me from a newbie mistake of not programming the solar controller correctly. I still don't think that being able to disconnect an electrical charging system is a bad thing. :-)  Again, see my post in this section on my 1230 watt solar install.

From other posts here, it appears that you too will be using the existing 6-gauge trailer wiring between controller and batteries. That line is already protected by a breaker in my trailer, and I am sure that it is in yours as well.

As to the number of panels on the roof, and future proofing, you also mention that you do not Boondock as much as you would like to. My feeling is that boondocking is where true rving actually is. :-)  My suggestion is to not skimp on the panels. If you use 72-cell residential-style solar panels on the roof, and particularly if you look for ones that use the narrower 5 in ingot, you will likely not have any problem mounting the panels longitudinally on the trailer, still leaving room to walk and not have to put any panels in series. That is a big plus during installation.

I found that panels were a relatively small portion of the total cost. Controller, shipping, and other items were a bigger portion of the total expense. Put as many panels on the roof as you can afford, and avoid having to redo it again later. :-)

As is often mentioned here, no one ever complains about having too much solar. The reverse is far more common. Once a person gets used to having the electrical conveniences when boondocking, the harder it is to do without when there is a cloudy day.
Linux:  Free, open, elegant.
06 GMC 3500 Duramax crew/long pulling 2010 Arctic Fox 30U with 1700 lb Reese Titan Class 5.
1.2 kw solar

HueyPilotVN

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Re: disconnects and fusing for small Solar system
« Reply #3 on: June 04, 2019, 08:08:33 PM »
This is how I placed the fuses in both the Stacker and in the coach.

I placed them at the input and the output of the controllers.  They are easy to disconnect.

I also placed catastrophic fuses at the input to the two invertors

I did the same in the coach.

The battery banks are under the counter below the invertors and vented to the outside


« Last Edit: June 04, 2019, 08:10:37 PM by HueyPilotVN »
Bill Waugh
2 Jeep Commanders
Mustang Bracket Race Car
Retired from the road to Lake Havasu after 35 years on the road
Now just another Lurker

blw2

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Re: disconnects and fusing for small Solar system
« Reply #4 on: June 06, 2019, 01:03:08 PM »
nice set-up...and thanks for the tips guys.

I should update...I ordered a Renogy 100W Wanderer kit a while ago.  finally had time to install it last weekend.
The kit didn't come with fusing.
Based on some other threads, I ended up adding these right at the connection to the controller.  One on the battery out positive...and one on the solar panel positive.  I chose them so I'd have an option at least to disconnect.

In hind sit though, I wish I'd put them in a more accessible place.
It dawned on me that I probably don't want to leave it on all the time while in storage long term
and the controller manual says to never connect the panels without a battery connected first
so I won't be able to use my disconnect at the battery.  I'll instead have to go click off the panels first
but I've got to wonder...why wouldn't they build protection against that into the controller...I mean, what happens when my battery side breaker trips for some reason....?  I asked Renogy..their response "If the charge controller is left connected to the panels without a battery, With time, the charge controller will be damaged. It will have energy coming in but nowhere to send it. "

with time.  Ok, should I assume 2 years time, so as long as it's less than 2 years i'll be ok? ;)

hmmm...maybe I should get a second relay, like the one Thor put in as a use/store battery disconnect.  Wire it so that when I hit the store button it fires at the same time so it also disconnects the panels....  nah, too much money and trouble I guess.  If it was a larger/better/more expensive set-up, maybe.... but not for this.
Brad (DW + 3 kids)
13 Thor Chateau 31L Class C on Ford E-450
'06 Silverado
'05 Rockwood Freedom 1910 (5-1/2 years)
former tent campers

Isaac-1

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Re: disconnects and fusing for small Solar system
« Reply #5 on: June 06, 2019, 01:27:54 PM »
I would think that while in storage would be the time you would  most want it to be turned on so the batteries stay topped off.
2002 Safari Trek 2830

blw2

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Re: disconnects and fusing for small Solar system
« Reply #6 on: June 06, 2019, 03:49:27 PM »
I would think that while in storage would be the time you would  most want it to be turned on so the batteries stay topped off.
yeah, well that IS one of my primary reasons for the solar...and what I originally intended to do...but it's in a lot and un-attended and I don't get by there as often as I'd like.  I'm just not one to love leaving things on for long periods with nobody there.
and then I figure once the battery is full, it'll hold for several weeks, so if i go by once in a while and flip it on for a day or two maybe that's enough
Brad (DW + 3 kids)
13 Thor Chateau 31L Class C on Ford E-450
'06 Silverado
'05 Rockwood Freedom 1910 (5-1/2 years)
former tent campers