Cabin near the forest, a lot o shade in winter, do solar panels work?

[J.P.M.]

Still at it huh ?

Speaking as someone who has been around alternate energy and solar in particular for about a half a century while changing careers to engineering along the way, your situation is simple to me.
You have an application that is not suitable for solar in winter and you don 't have the knowledge - practical or otherwise about or with solar energy technology - to see that.

Yes, PV can be done as can some solar thermal applications for summer or warm(er) weather use but even those will be impractical for a lot of reasons, mostly dealing with cost and hassle for what you get out of it.

So, Suit yourself and good luck but before that get informed about the practical limits as much as the advantages of alternate energy applications such as PV.

Some of what's meant as constructive criticism: Stop using electricity for tasks that can be done better with fossil fuel (like heating and cooking). Then, find a way to get propane to your site and get a generator to provide power and light for tasks that can only be done with electricity.
Some of the hassles of energy supply will still be present but they will be easier to manage, a whole lot more reliable, easier to maintain and probably less expensive.
If you do happen to wind up with some batteries, SUPER insulate the structure around them while still providing a way to heat and ventilate that structure appropriately and safely - check local codes even if you won't be following them.

Solar is not suitable for every application. IMO only, other ways of meeting your energy demand are much more appropriate for this application, starting with learning about where it's used and how to use less of it.

[Lradu]

Cabin is under construction, just now i am at the point i am really starting to install the system, also in this time i talked to a local company and defined most of the system, just putting in the final touches.
But, since i am an engineer my self, i like to do my research before hand and double check.

And i did understand a while back that i will not be able to rely on solar in the winter (the initial plan was a lot of solar + heat pumps, but that changed now). Still going with solar for summer but a smaller system backed up with a petrol generator for the rest of the time.

So, the final form should look like this:

- 10 solar panels on the roof
- 5kwh LiFePo4 storage (although i got a good offer on a 11kwh that i may change to)
- 5kw inverter
- back up petrol generator

Heating, cooking will not be on electric.
Only water pumps, lights, and the usual.

I don't want to take the solar part out since it is way to convenient (don't like the noise pollution and getting gas part of the generator) and the cabin will mostly be used in the summer so i figured this is the best compromise.

[Lradu]

The system is up and running now.

This is what I ended up installing:
- 10 x Longi solar panels 525W each (so 5.25 kw) that are split 5 on the est side 5 on the west side.
- DEYE Hibrid 5kW inverter.
- 12.5kWh LiFePo4 Battery

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The set up is there for the generator i only have to buy it. Will do that soon.

At the moment, very satisfied, all is working well, i never had the battery drop more then 10% over night or at any time.

I use about 2.4 kw/ day now when i am not there, and about 4-5 / day when i am there. But not everything is installed yet so i should be around 3kw / day when not there in the future. So 4 full days with no charge to drain the battery. This is how charging looks on a very cloudy and rainy day:
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Very curious to see what will happen come winter time, if the panels will be able to keep the battery charged at least with the consumption i have when i am not there i will be satisfied. Depending on that i will consider adding more panels if needed. Also thinking of a winter time solution where i add a few panels on a temporary structure a bit further down from the trees where i should get more sun. But i will make this decisions only after the first winter after i can get some stats.
I will post an update later in the year.
Thanks for the advice so far.
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[Lradu]

So, the first winter has passed over my off grid cabin. There was not as much snow this year, and also not that cold.
In December and January there is no direct sunlight on the panels at all, so in a sunny day i get around 200-250w/h from them, and when it is cloudy, the production goes up, but i don't remember anything over 800w/h (maybe for a very short time). Here is a good, and a bad day for winter production:
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And then... the snow came:
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Since it was the first winter, i experimented with the absolute bare minimum on when i am not there. So that meant around 1.2kw / day, but now i have all the things that i would like running when i am not there, and i am at around 2kw/day.
Of course, as predicted, with this low production numbers i got a generator, that has auto start, but i did not have the time to connect it properly so i could experiment with how well the auto start function works, so only manual start / stop for now.


But as i see it now, snow is my worst enemy. I could add some more panels on the roof, but when they are covered with snow it does not matter. It's not the easiest thing to clean the panels going out on the window on the roof, and i am also not there all the time. I do have someone that can go clean them but i do not want to rely on that.

Because of that, and the fact that the generator was not connected on auto-start, after the new year i switched off everything until middle of February. Of course, the temperatures inside went under 0C, leading to some errors on the battery when i first switched it on until the temperature inside it stabilized.

Realistically i think i will have to shut it down all the time in the middle of the winter. There is to much going on, snow, low production, low temperatures, the heater needs to run to keep the battery over 0. I don't think i can make it work.

But, i was thinking of a few things to help me with the snow and production come next winter:

1. I am thinking of something for snow melting/cleaning.
A I have seen some electric systems for solar panels that provide heat, but it's not feasible for me. I would spend to much energy that i do not have.
B I was also thinking of installing something similar to a floor heater that uses the house heater fluid and circulate it under the panels to melt snow. This should work with ought me using that much electricity since the house only uses about 200w to run, but i have some concerns if the pipes will be ok outside where it can go under -20C sometimes. Of course this will not be running all the time, only when needed.
C also i had the idea to make something like a giant wiper, using 2 rails at the end of the panels and an electric gate motor,. And some kind of a bar with silicone/rubber in between, so that when it snows i can run it up and down a few times to clean the snow. It should not be to difficult, and also not that expensive. Also the power usage should be minimal.

2. Also thinking of Installing another 2/4 panels as a temporary winter time solution, on the pontoon that i have on the lake, they should have sun all the time here, and install them at a big angle (so snow goes off them). But that does mean a few long wires and also i don't have any entrances left in the inverter.


Over All i am happy with the system, and it performs more or less the way i thought it would, but to be honest if there was a power grid closer i think that would have opened a lot more options for me in regards of heating and house control with less stress, But when i have sun, this thing is wonderful!

[azdave]

Your situation will probably never apply to me but I still appreciate the update to the project and the details. I can't imagine that any system to melt the snow would ever be worth the effort and system upkeep. It gets complicated really quickly when you start pumping fluids around or need extra energy for melting. The mechanical "sweeping" might be the only thing I would experiment with but even that sounds like a lot of effort and maintenance down the road. Looks like a beautiful cabin and area to live.

[littleharbor2]

Your situation will probably never apply to me but I still appreciate the update to the project and the details. I can't imagine that any system to melt the snow would ever be worth the effort and system upkeep. It gets complicated really quickly when you start pumping fluids around or need extra energy for melting. The mechanical "sweeping" might be the only thing I would experiment with but even that sounds like a lot of effort and maintenance down the road. Looks like a beautiful cabin and area to live.

Midnight solar had originally planned on putting a reverse energy flow system in their classic charge controllers. Apparently they decided not to do it because of the variables that may have caused them more problems with misuse and battery draining then it seemed worth it but it was a wonderful idea to be able to from your home far far away reverse flow back to the panels warm them up to melt the snow off via the Internet.

[solar pete]

Hey Lradu,

Wow, that's a great place mate, well done on your system and thanks for keeping us all updated on the project. Its always easy in hindsight but this is a lesson to all here, there is room on that roof for a few more panels I would have put a few more panels on ( granted I don't know about budgets and a bunch of other variables) as its always easier putting a few more on when your doing it, its always a pain to add them later.

I would be inclined to try to leave it running through winter provided you sort out the auto start on the genny and will be able to monitor it, nice work
cheers

[Lradu]

Thanks for the appreciation.

azdave i already have fluids running from my pellet central heater, so a smart wifi valve and i can open and close the outside circuit easy. The problem comes in running the pipes outside, and will they be efficient enough and reliable. So yes, i also lean a bit more to the big sweeping system. But i have to keep in mind this was a very mild winter, snow was max around 50cm (20 inch), and it should get much bigger then that in a normal year. I remember that when i first got the land, i went there in February, and the snow was so big i almost could not reach the place on foot, i would say it had 150-200cm (60-70 inch). Actually we just got snow there last weekend (unusual this late in the year), and even with fairly high temperatures in the day time, and the sun reaching the panels directly now, it took 4 days for them to clear with no intervention.

You can see here my first snow cleaning tool. Took half a day to clean them Now i got an telescopic roof rake, it's much faster.
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solar pete it was a request of mine to the guys installing the solar panels to make it so that if i want to add more later i could do that easily. And they say if i want they'll add some more easily. But the thing is, the back side of the cabin gets a lot of shade, even in summer. Panels are not that expensive now, i think i payed around 100euro for one. So 2-3 generator top ups worth of money. Problem is i don't think they would make that much of a difference. And if snow covers them i am back to where i started .

You can see here just how low the sun gets in the winter, and how much the trees block it
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Now when i am writing this post, and analyze all the pros and cons, I think if i sort the fact i don't have any more free ports on my inverter, adding some panels down on the water, on my pontoon where they should get at least a little sun all winter, at a high angle so that snow does not stay on them, cold be the best one and easiest to maintain!
That is especially since i already have 2 solar panels on it already because i have an electric motor and battery on the pontoon so that i can move around with it in the summer. In winter it sits on the shore (water level always goes down come winter time). So yeah, this could be the best one.
But even down there on the water it will not get that much sun
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Here there usually is water in the Autumn, so i could park it here. You can see the sun reaches this lower part where trees are not that close.
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And yes, it really is a wonderful place, i loved it since i was a kid an always wanted to have a place here. And i do feel like a little kid every time come.
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