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Russ459
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# Posted: 4 Jul 2017 12:53
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Hi all:
Many thanks for any advice as we try to figure out a solar set-up for our off-grid, remote, lake-access cabin.
I’m trying to decide how "big" to go, as I start off with a solar system. I suspect that down the road we will decide we "need" a bit more capacity even though as of now we enjoy being minimalists while at the cabin. We are on a 3 acre island on a lake north of North Bay, Ontario, Canada.
We are factoring for some lights; occasional electronics charging, i.e. phone, camera, nothing serious; and a 1/4 hp motor which runs our duro piston water pump, which runs for 5-10 minutes per day max (5 mins when it's just the two of us and 10 when we have guests up). This is how I'm coming up with a mere 500Wh/day. We do have a Yamaha 2800 generator which currently runs the water pump when we need to re-pressurize the water (large pressure tank, only once/twice per day for the two of us), and use propane appliances for everything else.
I'm not sure whether to go 12v or 24v. I'm thinking with 500Wh/day, and no critical applications, we just might get away with say 2 x 6v batteries for instance, and run 12v. Either that or we’ll decide we need more capacity and 4 batteries will make sense, so 4 x 6v for 24v.
I’m also trying to decide whether to go with (relatively) cheaper products, i.e. chinese “Tracer†style controller, readily available on Amazon.ca, or whether we should get a better one (what would that be?). My main concern would be when we’re not up for 6 months, whether the cheapie might fail… and/or fry my batteries...
Price around me is under $1 per watt CAD for panels, was thinking about 500w, either 2x260w or 3x180 for smaller more manageable ones.
I did pick up a 1000w 12v pure sine inverter locally recently but can still take it back (on sale at CTire $200).
More to my story:
We use the place only about 8 weeks per year, about 1 week at a time, sometimes 2 weeks, sometimes just a long weekend.
The main goals are to have some lights and to not have to start up the genny whenever the water pressure drops off, i.e. just switching on an inverter from inside would be awesome. No noise, no fuss, no muss.
I think the panels will have to go up on the (2-story) cottage peak, since it’s pretty surrounded by trees, so probably 30' from the batteries etc., and it would be shaded a couple of times during the day up there from the big white pines. There's a SSW facing shoreline about 250' away on our island, and the nearest shore is 40' from the cottage but it's west-facing at that point. I haven't done the math on line-losses and requirements for the various distances at different voltages, I guess that's next.
That’s where I’m at. Hoping to set up this September when we go up for a couple of weeks.
Again, many thanks in advance for any suggestions!
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creeky
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# Posted: 4 Jul 2017 15:11
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Hi Russ, this is a bit self serving. But look at my website
bobolinksolar dot com. I have small systems with lithium batteries. The batteries are a bit more. But last far longer and don't have the maintenance issues.
I would go two larger panels. Just for lower cost. Easier wiring.
I would skip the 12v. Go 24 or 48. Higher efficiency. Cheaper wire. Better long term investment.
Many quibbles of course.
And I would look at the Victron solar controllers. They are in the same price league as the Chinese controllers but they are far superior. Bluetooth monitoring. Super fast mppt algorithm etc.
Have fun.
PS-Ontario Lakeside posted a link to the video with his system. Have a real good look at his board. Its very nicely done.
He went 48v.
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Russ459
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# Posted: 4 Jul 2017 15:56
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Hi Creeky,
Thanks for the reply. I'm very intrigued by lithium--lots of things sound great: high quality, long lasting, no maintenance...
If I'm not up at the lake all winter, how does a lithium battery fare in the cold?
Thanks
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Atlincabin
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# Posted: 5 Jul 2017 09:56
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Seems you have a reasonable handle on the requirements. My only comment would be IF you go with a cheap inverter, try it at the store first to see how noisy it is. Some of the cheaper ones can have a very noisy fan. I would err on the side of too much power rather than too little, as you are bound to want more eventually.
Regarding Li batteries, I have some power tools that use them, and they sit all winter (9 months) without being charged and when I return in the spring, they are just fine, still charged. I worried about my AGM solar system batteries over that time so I put in a small vertical panel (no snow accumulation) with a small charge controller. When I leave for the winter, I disconnect the main set of panels and disconnect all potential loads, then connect the small panel to keep the batteries topped up over the winter. Probably overkill but I always end up with full batteries when I return in spring. And probably not necessary for the Li batteries.
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razmichael
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# Posted: 5 Jul 2017 18:28
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I'm sure Creeky has more up-to-date information but from what I know the main "issue" with lithium is that they should not/can not be charged in below freezing temperatures Battery University . This may or may not impact how well they suit your needs. My cabin sits through a very cold Canadian winter for 5 months or so. I leave my Lead Acid batteries connected and still powering an outside motion sensor driven light, camera and alarm - all very minimal draw but still active. Although the solar panels will end up with snow much of the time, they still provide enough of a flow to keep the batteries fully charged (i did check once last winter). Fully charged the batteries have no risk of freezing but would very likely be destroyed if they did not stay well charged. So far no issues through 3 winters. With Lithium things would need to be done differently to keep them charged over an extended below freezing stretch. Lots of advantages to Lithium but it does depend on your use case, budget etc.
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creeky
Member
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# Posted: 5 Jul 2017 21:20
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What they said.
Lithium shouldn't be charged below 5C. Ideally. Plates the anode or something.
But they can be used to -25. And you can unplug them when you leave in the fall and come back in the spring. No worries.
Best use guidelines say: discharge to 60-80% charge. Leave for up to a year. I left mine for a bit more than 3 months while I traveled this winter. No worries.
I don't put my panels away or anything. I just turned everything off.
This year I'm planning to stay for more of the winter. I am rebuilding my battery cabinet. Adding a charger for those long dark stormy days in Nov/Dec. Putting in some sort of battery compartment heater.
Its not a big deal. i used to keep my lead acid at 10 degrees C. I just lost too much capacity otherwise.
Because the lithium don't offgas I'm planning to put the inverter inside the battery cabinet. Insulate like crazy. I may get all carried away and use a relay to turn on a heater when the temp drops to say 7 C. And then turn off again at 14. Something like that.
For your low use you might be best served with a 24v system. Easier to find a good solar panel. Cheap 24v mppt. Good quality inverter. You're all set. I like 48 but the systems getting mighty fancy then for 8 weeks a year.
Atlincabin makes a good point about the inverter. Its the heart of your system. If you're going to indulge. That's a good spot. Batteries end up being the most expensive part now. Another reason I'm a lithium fan. Cheap! Cheap!
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beachman
Member
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# Posted: 9 Jul 2017 07:56
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I have almost the exact same system and have been running it for about 3 yrs. I have the CT 1000w PS inverter at 12v. Thanks to Cheeky, I added another panel and now have one 235w and another 255w in parallel to boost the amps and stay at 12v. I use 10awg from the panels to the Bluesky 25 amp MPPT charge controller (panels run at about 30v so wire gauge is OK to the cc). The run from the beach to the cc is about 40ft and we face west but I can face the panels to solar noon. I don't get full sun until about 11:30AM. The place is water access only with large pines so rooftop wouldn't work for me. The CT inverter works great and we have two 6v 350amp, lead acid batteries (on replacement will likely go lithium). We estimated 750 wh per day and the batteries hold up fine with use about the same duration as you. No expert but if you go with 24 or 48v, I think you'll need an inverter to match. My 2 cents.
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Willie1959
Member
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# Posted: 10 Jul 2017 07:56
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Get a bigger inverter, if you have motor loads. Check the surge load of the inverter. Use 24volt as panels as they are cheaper on kijiji ect. I bought 10, 250 watt panels last year for $60 each because animals had eating the leads and could not be used again for on grid systems. I have been off grid for 17 years and use lead acid battery's because I use the system in the winter. Don't do what everybody does in the beginning by under sizing the system. You have to take account of many rainy cloudy days in a row as well.. Current production has been about 500 kw since jan 2017 I use a monitor to check how much power I use.
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Willie1959
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# Posted: 10 Jul 2017 08:49
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Personally I would put the system at the SSW location. Put two 250 watt panels, with a 24 volt inverter 2000 watts, with a 200ah battery bank at that location in a weather prof shed . 250 feet is too far for 24 volts even with 120 volts you need a least 10 gauge wire to be safe when the pump starts . Have you considered a 24 volt surflo pump as they are on demand . That's what I use in the summer and my water source is 150 feet from the cabin.
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beachman
Member
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# Posted: 12 Jul 2017 15:16
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Creeky, not cheeky. Sorry - darn spell correcter. And many thanks to MtnDon especially about the grounding. Now, back to the camp!
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Russ459
Member
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# Posted: 15 Jul 2017 15:11
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Thanks everyone, helpful thoughts and suggestions. 
I'm going to run two 255w panels (in series) to a 24v system. I'm going to try the roof of the cabin, my estimations show that there's only about 2h of shading and I'm hoping the 510w of panels (even after some shading and other normal losses) will be able to boost the storage up after our minimal usage.
Willie I'm hoping that the piston pump will be able to handle the job. They are supposed to be efficient. It looks like a lot of folks like the sureflo pumps tho, so if the piston pump doesn't work out on our system I'll have a look.
Thanks again everyone and wish me luck! I'm excited for our first solar setup 
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offgridjunkie
Member
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# Posted: 16 Jul 2017 13:14
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Russ459:
Those 255w panels are most likely 24v panels right? If so, wire them in series so you have 48v coming out of the panel and use a MPPT controller to bring them down to 24V to the battery. That will be the most efficient way to run those panels and you will have less voltage drop over the run from the panels to the controller. Put that charger controller close to the battery and you are set.
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Nobadays
Member
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# Posted: 25 Oct 2020 09:55
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We use rooftop panels and have a bit of shading as well. You have had great advice here and have a good plan. My addition would be, go with name brand equipment, victron is a good choice (others would be Outback, Schneider, Midnite Solar) you will be at your cabin for fun and relaxation not to fiddle with the solar equipment. Secondly because of the shading, "over panel", or at least buy a Charge Controller that is big enough (40/100 - 50/150 at least that will handle 1000+ watts of PV) to allow you to add another string if you find the shading is not allowing you to fully charge. Lastly, Wiilie mentioned in his post to plan for rainy/cloudy days, depending upon your weather you really should have 2-3 days of storage. It's not totally necessary but it will allow you to enjoy your cabin even on rainy days without worrying about low battery cut-off or having to listen to the generator.
BTW we are also lithium users, they will set at 80% for months with little to no loss. Battleborn, Dakota, maybe others have all the safety features built in, hard to hurt them. They are spendy up front but will last 3 times as long as LA.
Have fun!
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Russ459
Member
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# Posted: 26 Oct 2020 10:55 - Edited by: Russ459
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Awesome advice looking back on this thread (I'm the OP, just got a notification)... I'll update in more detail when I get a chance but let me say thanks to all, the system is working great with two 260watt panels in series, a 100/30 MPPT controller, 800watt inverter and the 2kw of lithium batteries. Works a treat and with no sun does do us 3-4 days with zero to little charge per day. We always seem to get something unless it's really socked in in the winter. Have seen 78volts from the panels so happy we didn't go with a 75volt CC. May add more some day too for a fridge etc. Piston water pump has been great (knock on wood!), runs around 500watts for a few minutes/day. Victron stuff and NMC chevy volt batteries. Happy to answer any questions! Cheers all and thanks again 
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