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Littlecooner
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# Posted: 19 Jun 2017 10:46am
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OK, all of you with "off the grid experience".
Cabin is in the woods, During the growing season with leaf cover, no direct sunlight and the dormant winter season does provide some direct sunlight in any one spot for a few hours.
Question- if I try to charge the 12 volt batteries with solar panels, will I have any charging ability in the summer months with only ambient light?
Also help in recommending a solar charger panel. System will be very small. 4 - led RV lights around the cabin and one ceiling fan. Thats the total of the system and will probably use two deep cell golf cart batteries. Project is still under construction and I am a few months from installing anything, including lights
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Steve_S
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# Posted: 19 Jun 2017 11:21am
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There are different ways, one of the most common is over-panelling to compensate for shade but you need a good controller to handle such... a cheapo PWM controller will not.
Next, cut a few selected trees and give yourself a sunny spot for your panels. Sounds like something your not interested in doing but do consider it... what's a couple of trees in the grand scheme of things... You could always plant a couple to replace them if you have a need for "Guilt Trees". Might as well plant some Apples and get the benefits too.
Last option, most expensive would be to use a tracking system... Not anything I'd suggest for a small 12V system... the tracker would cost more than all of your offgrid kit put together in this instance.
There may be other ideas that could be applied but much of it depends on your land, layout and how to make best use of what Mother Nature provided on your spot. Small Wind Power may work but again, it really does depend on the land and things we can't know here...
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ICC
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# Posted: 19 Jun 2017 05:04pm
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To be effective you should use higher voltage panels such as those that are used with grid tie or 24 or 48 volt off grid systems. Then you need an MPPT charge controller to enable charging the 12 volt battery. Even on a cloudy day my system does produce enough power to do a slow charge; 80+ volts taken down to 24+ to charge the 24 volt system. The charge controller must be selected to cover the higher voltages being processed, which usually means several hundred dollars for quality equipment.
Forget trackers if you are as low budget as it sounds you are. And if trees are one of the reasons for the shade conditions forget wind power unless you can provide a tower that places the turbine 30+ feet above tree tops.
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paulz
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# Posted: 19 Jun 2017 05:32pm
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I have the same problem. My plan is to mount panels at the top of a tree, even ran a rope and pulley to get stuff up. Just haven't found anyone brave enough to work up there. I'm needed at the bottom, of course, to load the stuff. 
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offgridjunkie
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# Posted: 19 Jun 2017 05:45pm - Edited by: offgridjunkie
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In all reality, since you don't want to cut trees, and winter is not going to provide much either, I would suggest investing in a nice Honda or Yamaha 2000 generator, even the 1000 watt would do it and a high amp charger. Run the generator every morning for a couple of hours and your batteries will be charged. Especially on such a small system. If you use a good AGM battery, it will not discharge as fast when you are not at the cabin.
I used this set up for my cabin for 2 years while I planed my solar. I run a Dometic fridge, a few lights and cell phone booster with a 100 amp AGM battery. I never ran out of juice. With the solar panels, I never run my generator anymore, but by the time I was done buying all the parts, it cost me more than my EU2000
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NorthRick
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# Posted: 20 Jun 2017 12:19am
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Shade knocks down the output of solar panels substantially. Like maybe 20% of the panel rating. Even partial shade can do that. I agree with offgridjunkie, you are probably better off with a generator to charge up the batteries.
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bldginsp
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# Posted: 20 Jun 2017 12:40am
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The amorphous type panels are supposed to charge in shade with strong ambient light, but my little portable is worthless unless in full sun.
I have the same shade problem- eventually I plan to set up panels 400 feet away in good sun and run large aluminum feeders from there to the cabin. Substantial wire cost, conduit burial etc., but once done it's done.
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creeky
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# Posted: 20 Jun 2017 08:55am
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If you're putting solar far away from the cabin look at the new higher voltage charge controllers. They go up to 600v now. You can put panels 800 feet away with regular pv cable (rpvu). The u is for underground. So you're set. Conduit is a good idea.
Next week I install a system at 200 ft with a Victron 250v/85. Sure makes life easy.
Even a 150 gives you good travel distance. 100ft is nothing. Sometimes you'll need to run two or three lines (I'm talking 2-4kw of panels). But keeping the amps down and the voltage up. Well. look at your calculator.
MPPT does help. I have a buddy tho. He put his panels on a pole similar to what Paulz talking about. He gets 2 or 3 good hours a day. With lights. A water pump. Radio. 2 6v deep cycles and a 140w panel are all he needs. He's using a pwm controller.
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littlesalmon4
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# Posted: 20 Jun 2017 11:49am
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If you had a long run between the cabin and the panels would it not be most cost effective to have a battery house at the panels, invert at the panels to 120AC, then run the wiring to the cabin at 120AC. This should cut down the wire size considerably.
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ICC
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# Posted: 20 Jun 2017 01:58pm
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That depends on the DC voltage from panels to charge controller. If you take advantage of one of the newer high DC voltage controllers you are better off with a long DC run. I helped a neighbor setup his off grid system a few months back. Using Schneider equipment he is running over 450 volts over a 300 foot run. You do have to be more careful because that can kill you while 24 VDC probably will not.
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morock
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# Posted: 20 Jun 2017 02:38pm
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I started just like you, but found that if you never fully charge those two batteries they will deteriorate quickly.
I have used a 140Ahr Marine battery that has a handle for the last 3 years. I take it home and charge it up in the shed during the week and then grab it when I go to the cabin. I runs the entire place for the weekend, that includes TV time, lights and 12V water pumps too. Its pretty much done by Sunday but has held up well and lot less than a mini solar setup.
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spoofer
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# Posted: 20 Jun 2017 07:02pm
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I ha ve a 100 watt Renogy panel. mppt charge controller 2 golf cart batteries.. Runs 4 led lights, a small led TV and a radio all weekend.
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Littlecooner
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# Posted: 20 Jun 2017 11:17pm
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Thanks for all the input. I think I will start with morock's plan and use a generator also. I am still months away from spending the first night. Goal is to be ready to spend time this fall and hunt some from the new place.
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offgridjunkie
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# Posted: 21 Jun 2017 11:00am
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I think you will be surprised at the how well your plan will work for a little weekend get away.
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Durk
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# Posted: 21 Jun 2017 12:49pm
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There has been great advice on this question. My situation is very similar to Littlecooner's as far as power needs. I'm looking at solar also but my main problem will be cloudiness in the cold dark months of a Montana winter (when I need the power most). As with Cooner I may be better off to just use my generator, but is there a type of panel that performs better in cloudy conditions? Does cloudiness affect panel performance to the same degree as shade does? Also, can anyone recommend a charger to use with a 2000 watt generator for charging 2 deep cycle golf cart batteries? Thanks.
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creeky
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# Posted: 22 Jun 2017 08:12am
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Cloudiness is cloud dependent. In the late fall/early winter here I've had cloudy days where I make 40 watts of power a day. And two months later, same length of day, I've had 400 watts an hour, also under cloud.
With cloud it helps to have the panels facing the sky. The light comes straight down. Not useful in the winter when that cloud also carries snow. But winter solar, less humidity, cold panels, is real powerful when its going.
I like the PowerMax chargers. They are inexpensive and reasonable quality.
Put some solar in. You'll be surprised what you can get with even a few hours of sun. or more hours of cloud. And not just the quiet. You save money on gas. When a panel is 100 bucks. Or 2. Pays for itself year one. Now think year 10.
And everyone I know who has set up a system reports back that it works better than they had expected. I include myself in that. I've paid for 1/2 of my system just on propane savings for the fridge.
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Durk
Member
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# Posted: 22 Jun 2017 09:08am
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Thanks Creeeky. I'm not there full time, so automatic battery charging would be nice. And I like quiet.
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offgridjunkie
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# Posted: 22 Jun 2017 11:38am
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Quoting: Durk Also, can anyone recommend a charger to use with a 2000 watt generator for charging 2 deep cycle golf cart batteries?
I have had great luck with the IOTA 12 Volt 25 AMP charger. I use it to charge 1 - 12volt 100 AMP AGM battery. I will be upgrading my system this summer to 24 volt and I will be replacing it with the 24 volt model.
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241comp
Member
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# Posted: 27 Jun 2017 04:08pm
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Ok, I have some practical information to share on the topic of solar in the shade.
First, my setup. I have a 6-panel solar array (configured 3x2) using REC280TP panels for a nominal 88.47V and 1230W @NOCT. I run these panels through a Midnite Solar "The Kid" (MPPT) charge controller, charging a 36V, 210AH AGM battery bank. The panels are not oriented "ideally" on either axis, rather are oriented in the simplest manner, fixed to the south-easterly facing roof of a small cabin.
What does this have to do with "Solar in the shade?" Unfortunately, during the summer these panels are in partial (or full) shade all but ~1hr/day. Because of the TwinPeak technology, these panels can generate more electricity with partial shading than traditional panels. However, in full shade, these panels are no different than any other similarly spec'd solar panel. In full shade at mid-day (on a sunny June day), I have seen these panels generate 268W. That is ~22% of NOCT and ~16% of their STC rating.
Because of their orientation (and possibly other factors such as low ambient indirect light due to nearby heavy shade), during direct sunlight I have not seen this array exceed 680W. That means this array generates up to ~39% of its "direct sunlight" capacity when in full shade. But, I should note, full shade is different than "deep shade". Although the array is in partial or full shade the majority of the day, there is sunlight on about 30% of the surrounding area at any given time. You will certainly see different results with an array in "deep shade" where there is almost zero direct (or even filtered) sunlight in the surrounding are.
On that sunny June day, the array generated nearly 1.8KWh of electricity, with about a third of that occurring during the ~1 hour of direct sunlight, one third occurring during partial-sunlight and the remainder occurring in full shade.
Hope this helps!
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NorthRick
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# Posted: 27 Jun 2017 07:20pm
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Quoting: Durk There has been great advice on this question. My situation is very similar to Littlecooner's as far as power needs. I'm looking at solar also but my main problem will be cloudiness in the cold dark months of a Montana winter (when I need the power most). As with Cooner I may be better off to just use my generator, but is there a type of panel that performs better in cloudy conditions? Does cloudiness affect panel performance to the same degree as shade does? Also, can anyone recommend a charger to use with a 2000 watt generator for charging 2 deep cycle golf cart batteries? Thanks.
We're in Alaska, so we know all about the cold dark cloudy months of winter. We use a combination of solar and generator. Solar serves 100% of the need about 1/3 to 1/2 the year (spring/summer), serves part of the need about a 1/3 of the time with the generator making up for shortfalls, and from December through mid-February, solar does almost nothing and we rely on the generator nearly 100% to charge up the battery bank.
We have one of the IOTA chargers and it seems to work well.
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gcrank1
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# Posted: 20 Dec 2020 10:46pm
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If your winter solar elec use is modest the limited recharging time may not be too hard a hit. With us the shorter and darker days mean more use of the highly efficient LED lights, no big deal that. And maybe more radio.....the big one is the ceiling fan to kick the heat out of the top from time to time though Ive been using a little 5" usb plug in fan with decent success. It isnt a lot of cfm but it does circulate the air in our 16x24 with cath ceiling. Any big draw is taken care of with the gen for a little while and when it runs the smart charger is always on the bat-bank too.
Ive found the poorly sited array (e-se because s-sw is tall pines) picks up irradiance better with snow on the ground than not. And in the cold the array 'is supposed' to kinda spike though I cant prove it, that should help the output/uptake.
And I carry one of the older larger 'jump start packs' (something like a 17ah dc battery inside that stays topped up in transit off the suv cig-lighter socket) as a back-up battery for inside. I can hook up the 300w psw inverter right there if things were to go wonky with the power house set up 30yds away in the cold and dark (I invert to 110vac there). So far we have been doing well with this modest system for our occasional use cabin; we hardly use the reserve due to conservative elec demands. I am confident that were I to stay a week or more that I would not deplete it anywhere close to the 'hard on the battery point'.
Some of the best advice I got on solar livin was to conserve first and all LED lights sure are a boon compared to the old 12vdc incandescent Edison base rv bulbs I used in Cabin-1 in the way back, a single 50w bulb used 2+ amps/hr, now I can run 5x9w LEDs at the same time for less draw and light up the whole inside like a house on the grid. I usually only run 1 or 2 though and do just fine with 'zone lighting'.
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gcrank1
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# Posted: 20 Dec 2020 11:05pm
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Looking at the orig post again I see that the 'needs' stated were not dissimilar to what ours have been. Given the heavy cover I would probably not recommend solar, Id suggest putting the money otherwise spent on it into a LFP battery at much less weight and more ah's usable; lead acid should not be used more than 50% of available so 230ish ah's of 2x6v in series would at best be 115 when new and the batteries would last longer if only depleted to 75%soc, thus really 57 ah's. The LFP you can regularly use 80% of available ah's. I think I would buy one 100ah LFP (80ah's usable, if I understand this correctly) and transport it home to recharge between trips or buy 2 and swap out each trip. I would not want to be lugging GC batteries to do that! Id still want an inv/gen and smart charger for the LFP at the cabin too. If Ive done the calcs right the inv gen, LFP battery and a charger should cost less than putting in a solar-elec system that might be only 30% efficient.
Btw, if full timing off-grid the 'take home to recharge' thing wont work, will it.....but maybe you could do the 2 batteries and keep the charger at a friends place on grid to keep a battery charging for you between swap outs. Unless yer a total hermit.
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