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Borrego
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# Posted: 9 Apr 2018 10:20pm
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I just installed a great solar set-up this season.(my season in the desert runs from Sept - May) and we're getting ready to shut the place down for the summer.
I've asked my solar consultant and he says to go out once a month and turn it on for 3 hours to charge the batteries.
He's been great and I trust him, but just asking....
Does that sound about right?
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Borrego
Member
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# Posted: 9 Apr 2018 10:22pm
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Anything else you would recommend?
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ICC
Member
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# Posted: 9 Apr 2018 10:52pm - Edited by: ICC
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What batteries? Good reliable charge controller or something found on ebay?
I have a remote cabin that sits empty for months on end and leave everything to run itself. Midnight Solar CC with lead acid batteries. That runs through the winter with maybe only a monthly visit. Always find the batteries full and ready to use. With no actual use water use in the batteries is not a problem at all. Absorb runs on the end-amps basis so never runs longer than necessary. If you time absorb you can reduce eater use by shortening absorb to maybe 20-30 minutes.
It also is well protected against lightning which is a concern some of the year.
System has been running for 10 years now. Maybe this year l will change the batteries.
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darz5150
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# Posted: 9 Apr 2018 11:38pm
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If your setup will power what u need when you're there and keeps the batteries charged and healthy. Why would you need to shut it down? And then go back to turn it on.?
Your charge controller should baby sit your batteries and keep them happy.ðŸ˜
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razmichael
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# Posted: 10 Apr 2018 10:23am
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Yah - not sure why you would need to disconnect the batteries? Although I have a main OFF switch at my cabin - this just disconnects power to the cabin. Controller, panels and batteries remain hooked up and I power motion lights, cameras off the controller LOAD connection. This gets left like this over winter (6 months in Quebec so cold!) with no attention. Spring I top up the batteries with water (and they have never been too low) and good to go.
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Borrego
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# Posted: 10 Apr 2018 12:01pm
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I have (8) x 6volt AGM sealed batteries. All other equipment is Schneider, MPPT controller, AC Box, DC Box and Inverter....
This is why I'm asking, the online consultant that did a wonderful job of getting the equipment and guiding me through install, says I need to go out no more than 6 weeks apart, turn it on and let the batteries charge for 3 hours, then turn everything off.
This is my first season with solar and I love the system, just want to ask around to make sure I'm doing everything possible to protect it....
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razmichael
Member
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# Posted: 10 Apr 2018 12:27pm
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Might be worth going back to him and asking him "why". That might make it easier for other to provide more feedback/opinions.
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Borrego
Member
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# Posted: 10 Apr 2018 04:58pm
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Quoting: razmichael Might be worth going back to him and asking him "why".
The answer was that electronics are safer from lightning if they're off.....
True I suppose.....not much lightning out in the desert....
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ICC
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# Posted: 10 Apr 2018 09:23pm
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I have had DC high voltage rated breakers blown apart by lightning.  One was installed before the charge controller and was in the off position. Lightning struck the array and followed the wires to the breaker just before the CC. The breaker case was split in half. The lightning jumped the breaker gap and destroyed the CC. On the other side of the batteries the lightning blew the breaker to the inverter DC + and toasted the inverter. That breaker was also left in the off position. The equipment was a Midnight CC and Magnum upper scale inverter. Then lightning traveled inside the cabin on the AC wiring. The batteries, flooded Rolls, survived seemingly unscathed. Everything else that was plugged into the AC wiring had the electronics toasted. The DC ceiling fan survived but the electronic speed controller blew as did the 24 volt to 12 volt converter. Device motors survived but not the electronics that controlled the motors. The LED lights were all okay except for one. A few things like the vacuum cleaner with electronic controls and tool battery charger were unplugged from the wall and were okay.
NOW, I have an elaborate lightning arrestor system arrayed around the roof with several down wires and ground plates, plus a better grounded array and wires. I leave the system run all the time BUT have a quick disconnect system on the wires from the array to the CC. During lightning season I pull the cables which provides 12 feet of separation between array and CC.
The system also has several Midnight and Delta lightning arrestors in place; the array, the CC and the inverter sides of the batteries have DC rated versions with AC versions at the service panel. Those operate on different principles and I figure you can't have too much lightning protection.
Being in the desert one potential problem with grounding to earth is the lack of enough moisture in the ground. I'm in semi-arid mountains and also spent time and effort to direct water to the areas I dug holes to bury the ground plates. The plates are copper and provide greater surface area and with a quite low resistance. Better than any rods I have measured.
The AGM batteries can handle the no charging with the array or CC turned off for quite long.
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Borrego
Member
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# Posted: 10 Apr 2018 10:18pm
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Thanks ICC, and guys....
I still don't know quite what to do.....
Guess it wont kill me to drive out to the 125 d god-forsaken desert in the middle of the summer once a month 
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Borrego
Member
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# Posted: 11 Apr 2018 09:31pm
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So.... is the general consensus that I don't need to go out and check the system every month? Or is it safer to go out and turn it on and off?
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Just
Member
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# Posted: 11 Apr 2018 10:14pm
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I only have a small investment compared to you say less than 1000$ but I have never shut it down in 12 years ( one battery change ) . With your investment I would go out and check for a few times until you gain cofidence in the system . Solar is like a mother’s first baby she needs to check often to make sure it’s still breathing.
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darz5150
Member
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# Posted: 11 Apr 2018 10:32pm
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I wouldn't worry about it. Even if you drive out monthly to flip a switch. There's nothing you can do if lightning hits your cabin instead of your solar system .
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FishHog
Member
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# Posted: 12 Apr 2018 09:07am
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I wouldn’t bother. In fact I don’t with my system
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ICC
Member
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# Posted: 12 Apr 2018 09:52am
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Quoting: darz5150 There's nothing you can do if lightning hits your cabin instead of your solar system .
There is; I think. I should have mentioned that in the three years since my place was hit by lightning and I installed the roof top rods and all the ground=ing apparatus I believe we have been struck again, more than once, probably more than twice. I have replaced two of the Midnight Solar lightning arrestor modules, they call them surge protectors. The Midnight units use electronics to sense and shift the lightning to ground. I forget what those electronic parts are called for sure (MOSFET?)but they get used up a little with each strike or surge. Midnight incorporates a bright blue LED that is lit when they still are working. I've had two of them need replacing. So, I think they have saved the system, as nothing else has been damaged and the system is left in a full working state most of the time.
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Borrego
Member
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# Posted: 12 Apr 2018 10:19am
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ICC - I have the same Midnight Solar module installed, just FWIW...
sounds like the general consensus is to not worry about it, so I'll just check on it when I'm out there to check the cabin anyway...
Thanks, cabin friends!
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creeky
Member
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# Posted: 13 Apr 2018 08:52pm
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I shouldn't point out that if the battery was lithium you would discharge to 80%. Turn off the system. And then walk away worry free for up to a year.
I've had various reports back from year one with my PowerWIngs in cottages. One system was down 3/4 of a volt. My system was down 1/5 of a volt (I was only away 6 weeks). So absolutely nothing to worry about.
Why worry?
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NorthwoodsGuy
Member
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# Posted: 14 Apr 2018 01:16pm
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Creeky- That's a good point. Another good reason to go Lithium.
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DonCallis
Member
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# Posted: 17 May 2021 09:29am - Edited by: DonCallis
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I think your solar consultant is right about charging batteries once per month. It's nothing to worry about unless you have a defective charge controller. It exactly what happened to me when I tried to charge the batteries last year. I had to spend some money and replace the charge controller. It was hard to find exactly the same model I needed, but in the end, I found some old controllers on eBay. But I had to purchase some automatic spare parts too because this controller originally didn't have enough power. I had to repair it on my own, but the results were quite good.
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gcrank1
Member
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# Posted: 17 May 2021 01:21pm
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One of the members has a recent fairly long thread regarding how his system 'failed' in his absence and wiped out the whole battery-bank. At least it was LA not LFP, but still way expensive and troublesome to sort out.
It, too, was a case of a fairly new system and user still in the learning curve.
I dont know how good you are about staying away from the place in the off season, we went to ours this last winter several more times than we had expected.
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redwolfguild
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# Posted: 24 May 2021 07:54pm
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Borrego - I have been doing what you are going to do in reverse for 7 years now. I set my system so the panels are connected to the charge controller then to the battery. The inverter is connected to batteries but I have a breaker in between the battery and inverter. When I leave, I disconnect the batteries from the inverter and the rest of the house. I let the CC run connected to my batteries to keep them perfectly charged. Still on the same set of Trojan AGM Deep Cycles I started with. I am in the mountains and if my place gets struck by lightning, My place will probably a total loss anyway.
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gcrank1
Member
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# Posted: 24 May 2021 08:16pm
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LA wet cell batteries love to be kept charged and trickled. They dont like to cycle in particular, but do.
Once discharged they want to be recharged asap, this for me that means dont discharge too deeply and get the recharge started asap the next day. Ive let my solar run through the cc to keep the agm's topped for 2 winters now. Nothing is hooked to the bat-bank in my absence. Nothing, I dont depend upon a switch.
If I had LFP I think I would end my season with my last day of use, discon the battery and let it sit all off-season and discon the array from the scc.
All off, easy to hook back up on return and not charge the LFP until the battery was above 32*F, not just the air. That LFP sitting alone would be ready to use as is without being charged or even hooked up to the cc.
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Daaaaaaaan
Member
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# Posted: 29 May 2021 04:50pm - Edited by: Daaaaaaaan
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"If you don't use it, you lose it". And that loss is through higher panel temps.
A cool panel is a happy panel.
Unloaded panels run hotter than loaded panels as the load is moving 10-20% of the solar energy away.
(Unfortunately, a lot of panel temperature models look at temperatures 'open-circuit', but 20% panels will be able to pull 20% of the energy away, while 10% only 10%!)
I know OP's post is old, but I cringe to think of how hot panels get when left unloaded in the desert all summer. It's not going to instantly damage them, but will accelerate degradation over the years/decades. Or tilt them away from the sun for long-term times away.
In an occupied off-grid application, running your panels at full-load with dump-loads will keep them a bit cooler so they're a bit more efficient and let you draw more when it's needed, lowering battery cycle counts.
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