Author Topic: Solar for a cabin?  (Read 3265 times)

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wine_guy_3

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Solar for a cabin?
« on: October 20, 2016, 03:39:55 PM »
Hi all,
I wanted to put up some panels at the (way off grid) cabin.
I only use the cabin 20 some days per year.
I want to run a small refrigerator (about 1kWh per day), and some led lights.
I have 400 W of solar panels and 2 (115 Ah) batteries.


The panels should charge the batteries in a few days, but then what?
Sounds like a lot of wasted power and sun-lit panels.
Do I put up, and take down the panels every time I go to the land?

Does anybody here have the same cabin situation?

george65

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Re: Solar for a cabin?
« Reply #1 on: October 20, 2016, 09:43:51 PM »

If you are leaving the batteries there you will want to keep them charged.  Leaving them to sit and discharge will stuff them up real quick.

As far as the panels go, What are you worried about, wearing them out?
They would be guaranteed for 20 years.  They will undoubtedly last a lot longer but are you even going to be here in 20 years to worry about them?
Pretty sure I won't be here then.
If you are planning to be,  If they haven't replaced solar panels with something else, they will be so cheap you won't give a damn about getting something newer, more powerful, smaller and compact.

Maybe you could put the excess power while you are away to another worthwhile use?
 A small fan to circulate air in your cabin to keep mould from forming and the air fresh? Run a pump on a timer to water the grass around the cabin or top up your water tanks? Put in a small hot water heater and trigger it through your Phone to turn on a day or 2 before you arrive?

If the batteries aren't going to stay onsite then I suppose you could  just have the panels on the ground while you are there and put them away to keep them a bit cleaner till you come back.

OperaHouse

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Re: Solar for a cabin?
« Reply #2 on: October 21, 2016, 08:39:18 PM »
I take my panels in at the end of the season, mainly because they sit under a tree.  I have a couple small panels to keep the batteries charged when I am not there.

george65

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Re: Solar for a cabin?
« Reply #3 on: October 22, 2016, 02:48:46 AM »
I have a couple small panels to keep the batteries charged when I am not there.

I thought of Suggesting that but then remembered where i am at least, I can buy a 200-250W used panel a LOT cheaper than I can buy a 20W new panel. Rarely see the small ones come up used.

OperaHouse

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Re: Solar for a cabin?
« Reply #4 on: October 22, 2016, 08:09:26 PM »
Personally I think you are heavy on batteries and shy on solar panels. I have 1500W of panels to insure fridge operation.  Of course my system is totally different than a standard system.  Still, I would double the panels.  My panels are almost at ground level and lay in so there is no problem bringing them in.  And there is a high potential for damage if I leave them out.  I have panels that have seen less than 2 years of sun and thy are now worthless.  Extra care didn't save them.  So whatever is practical in your application.  You would need at least a 100W panel to keep those batteries charged. 

george65

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Re: Solar for a cabin?
« Reply #5 on: October 22, 2016, 11:18:57 PM »
I have panels that have seen less than 2 years of sun and thy are now worthless.  Extra care didn't save them. 

What happened to your panels?
Was it Physical damage from something like falling limbs or....??

OperaHouse

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Re: Solar for a cabin?
« Reply #6 on: October 23, 2016, 02:08:29 AM »
I was only using them 6 weeks a year and after about 5 years they had noticeably weakened.  They were identical panels so I was able to use  the good 6V sections of each panel in series to make one equivalent good 12V panel. A few years later I tested both of them again and the good sections are dead.  Visibly no imperfections can be seen.  The warranty was useless.  Of course these are older panels and quality has improved.  Have a couple other panels that are questionable but haven't thoroughly tested and are in the rat pack of mismatched panels that are only supplemental to the system. They show spider webbing.  I now run at higher voltages that require matched panels.  Don't expect to get more than 50% of the panels power rating.

wine_guy_3

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Re: Solar for a cabin?
« Reply #7 on: October 23, 2016, 07:05:16 PM »
Thanks for the inputs.
In the short term I will "bring them in" when I leave.
I have some large patio doors that can provide some sun.
I can stand them up inside to provide enough power to keep the batteries charged.
This will keep them out of the elements, and away from thieves while I am not there.
I plan on hanging them near the gutters, from the overhang while I am there.

Eventually I will put up a pole so I can mount them permanently.
Once again thanks for the inputs.

P.S. where do you folks find used panels?
I look around every once in a while, but not much pops up.
At around $1 per watt, I'm not sure if used ones are worth the bother.

george65

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Re: Solar for a cabin?
« Reply #8 on: October 23, 2016, 11:46:18 PM »

I find them on Flea bay and Dumbtree.
There are LOADS of them here for sale that are only 2-3 Yo. People are either upgrading their systems and want to get all the same panels or they are insurance jobs. Only one panel needs to get damaged and they will again replace the lot to make sure they all perform right.

I'm hoping to get some this week from a guy that has a heap of them. 5x 225W panels for $200.  More like .25C a watt and they are good quality Tier 1 panels to start with. From the pics on the ad, I'm not even sure these things are used. Seem to all be from boxes in pallets so unless a solar farm somewhere either closed down or upgraded, I'm thinking these things could be in fact new.

I'm going to check the seller out and what his stocks and panels are with a view to buying in bulk and reselling them myself.  My father lives in the country so If I can make some money taking them to where he is and on selling them, might pay for the trips I was going to make anyway.

There are ship loads of these used panels around here, just some sellers are more realistic than others.  People advertise used gear all the time for more than they can be bought for new.  Obviously they bought a system 5 years ago and are going on a second hand price for what they were worth then, not what they can be bought for new new now which is less than what they want for old 150W panels that are out of date with current technology. 

I posted recently about these used panels being so cheap, I would look at using them to build a veranda/ patio cover out of in the future.  I crunched some numbers and worked out that even when placed in a less than ideal angle and orientation, the difference in price between doing a covering in panels and in normal roofing material would be paid for well and truly under 2 years.  By the 5 year mark I'd be ahead on the cost of the whole structure that I wanted anyway.  I looked at a couple of houses on teh weekend and both would be good for this One had perfect orientation and the ability to get the right angle and the other was near orientation and I could get a good winter angle.
 If they didn't happen to be facing near the right direction and I could get some decent tilt on the things, I'd still be laughing. I'd look at these primarily as a backup or add on but they could work real well in an over kill system.
They may not even be needed on sunny winter days but on hot summer days and cloudy ones, the extra panels would be awesome.

The affordability of off grid in suburbia is becoming closer all the time here. I see 30Kw battery packs being advertised for $3k With 2 year warranty.
Storage as well as generation is affordable. Biggest cost is going to be inverters and Charge controllers.
With a 30 Kw reserve, All I'd need is the lister or a diesel genny for a battery charger to run to cover the maybe 2-3 weeks a year of continuous wet weather we get and maybe a week of odd days I'd have to top up and that would be it.

People always talk of rising power prices but they have shot up so much here in the last few years I don't think they can go much further. The power companies have to know that they are near if not at the tipping point where people are going to start investing in serious consumption reduction even on grid and a proportion are going to bail all together.  You'd have the DIY'ers, the green washed and just those that will sink money into avoiding getting screwed on principal just to start with. Many home builders now are throwing in 5Kw solar packages to their packages and the overall energy consumption  of houses is falling anyway.

I don't really subscribe to the theory of spiralling power prices because where I am, I don't think there is too far they can go before they start going backwards.

We'll see though. Plenty of places pay more than what we do here so there is still margin to go yet.  Don't think it's going to worry me although it might be wise to stock up on these used panels while they are still cheap and everyone else doesn't wake up to them.