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

[Lradu]

Hello friends,

So i have an off grid cabin, in a wooded area. It is on a slope north facing, and in the back there is a lot of tall trees. In The summer, when the sun is up, there is no problem, but in the winter there is a lot of shading, see photo:
cabana.jpg

Keeping in mind that this is February, so in mid December the sun is even lower, so more shade. The photo is about mid day, there is also a bit of sun in the afternoon, but not that much.

It is going to be a cabin, so especially in the winter time it won't be used all that much, but still i would like to go some weekends.

Heating will be on a wood an pallets boiler, no big energy consumption there, so only lighting, freezer,Tv and the other usual stuff. If i get enough power maybe an electric water boiler when the heating is not working (that is summer time when i have enough sun).

For the system i was thinking:
- solar panels on the est and west part of the roof (6 or 8 of them).
- 6 to 10 kw of storage
- generator ? no idea what to use.

Will the solar panels work at all in this situation ? What should i look for? I am sure in the summer 6-8 panels will be enough, but what about in the winter? Is it worth it to put more? My thinking is that even if i fill the roof with panels i won't get enough from them, so still relying on the generator, so no need to push it to much.
How about the generator?

Thanks!

[SunEagle]

Depending on your loads and size of the battery I would say it can get very expensive to have a sola/battery system at that cabin.

My guess is that depending on how long you stay there even a generator may get expensive.

By the way if you have batteries you should still get a generator to keep them happy since you may not get enough sunlight.

[Mike 134]

I'd use google to get some rough ideas of pricing your solar/battery system vs a 5500 propane KW generator. See what the propane company will charge for say 100 gallon tanks, lease VS buying.

[Rade]

When they were sizing our property, the question asked by the site surveyor was "How much do you really love that tree...?"

We have a Cypress tree that blocks a lot of early morning light. We kept the tree. Made no difference.

[J.P.M.]

Will the solar panels work at all in this situation ?
How about the generator?

Thanks!

PV will pretty much be a waste of $$, time and resources in the winter.
Summer might be a different story.
Either way, summer or winter it'll be expensive, especially for the required batteries.

Get a generator that'll run on propane.

[oregon_phil]

I have a tree that shades some panels when the sun is low on the horizon during wintertime. We had a very clear sunny day last week. Attached is data from my Tigo optimizers for 8 adjacent panels. One panel had shade on it. Not solid shade, but shade from the top of a fir tree that is marginally healthy. Eventually the tree will get cut down, but we don't really get too many sunny clear days in the winter so the benefit of cutting the tree down isn't all the great.

The OP's roof photos show lots of shade and will greatly limit panel output.

[Lradu]

Thanks for the ideas

I don't think propane is a good option for me, there is around 1h of driving to the nearest city, and the last part is not that easy to get in with a truck so that can get expensive.

The electric grid is about 3-4 km (2-3 miles) from me, so maybe that would be a better option, but it is complicated and very expensive.

So i am going to go with the hybrid system of solar panels + generator (diesel o gas). That way i have no stress in the summer when i will be using the most of the cabin, and in the winter i am going to rely more or only on the generator to charge the battery. no big deal.


I found a good deal on solar panels, so i am going to go with 10 of them.
Also found a battery from an electric car (some kind of hyndai) 9,4 kw with 1000 eur. ( i live in Europe ) I figure that that should last me at least 2 days if fully charged.
Generator - not decided yet.

[J.P.M.]

Thanks for the ideas

I don't think propane is a good option for me, there is around 1h of driving to the nearest city, and the last part is not that easy to get in with a truck so that can get expensive.

The electric grid is about 3-4 km (2-3 miles) from me, so maybe that would be a better option, but it is complicated and very expensive.

So i am going to go with the hybrid system of solar panels + generator (diesel o gas). That way i have no stress in the summer when i will be using the most of the cabin, and in the winter i am going to rely more or only on the generator to charge the battery. no big deal.


I found a good deal on solar panels, so i am going to go with 10 of them.
Also found a battery from an electric car (some kind of hyndai) 9,4 kw with 1000 eur. ( i live in Europe ) I figure that that should last me at least 2 days if fully charged.
Generator - not decided yet.

Given your remoteness, I'd question whether any fuel delivery will be easy or even possible. Propane trucks are large but not gigantic. gasoline or diesel fuel delivery trucks are not that much smaller. Depending on your electrical demand, running back and forth to a gas or diesel station may become a PITA. Also, some locations do not allow or restrict filling of portable tanks.

On the diesel: Depending on how cold it gets at your location, you may want to consider how you will keep the fuel above its "jell" or cloud point which is ~ -10 C or so, +/- a couple of degrees C. depending on fuel formulation. The jelling of diesel fuel occurs as wax (paraffin) in the fuel (which helps make the fuel more uniform and improve its viscosity) solidifies as the temp. drops. When it does it will prevent fuel flow and so prevent the engine from starting, or if very cold, slow or stop fuel flow altogether to a running engine.

If your electrical demand(s) are relatively small (say 2-3 kWh/24 hrs. or so), maybe a small, portable gasoline fired generator might be suitable provided you can get the batteries to function.

Without out knowing more about your situation and specific energy demands it's hard to offer meaningful suggestions beyond general information, but it looks like PV isn't a workable winter solution for this application.

[PNPmacnab]

I'd investigate bifacial east west facing vertical panels. These can work fairly well in snow catcing ambient light in combination with normal array installation. There is always a way and panels are cheap.

[J.P.M.]

I'd investigate bifacial east west facing vertical panels. These can work fairly well in snow catcing ambient light in combination with normal array installation. There is always a way and panels are cheap.

Depending on the application's latitude, this may help in the warmer seasons, not because of temperature but due greater irradiance of E-W facing panels brought about by larger azimuth angles. Conversely, and again depending on latitude, it may make any winter PV production worse than other (single faced) panel orientations. Albedo effects won't have as much or even less enhancement E-W panels in winter.
Also, if E-W panels have a high(er) tilt angle, their summer production will suffer.

[PNPmacnab]

I should have added that I wish I had that solar site. I have nothing but shade on 70% of my panels. I would have no problem operating on that site. This is interesting Show (youtube.com) Vertical Bifacial Solar Panel Performance Results Part 1 - YouTube

[Lradu]

@J.P.M.
Good point about the diesel. No problem in getting gas in portable tanks where i live.


Regarding my electrical demands i put them in the first post, but will elaborate:

- Heating will be on a wood an pallets boiler, almost no energy consumption there.
- general demands like: TV, Fridge, Lighting and other usual stuff.
- electric stove (but that should not be used all that often)
- water heating on electric only in summer (when the heating is not running)
- surveillance system all the time (but that is a small energy consumer)

I would say that is fairly low.
I would say even if i run only on generator with no solar help 20l / 5gallons of gas should be more then enough for a weekend. I can live with that (i think ) )


The latitude is 46.5N

@PNPmacnab interesting video. good info to know. How many panels do you have at your location?

[PNPmacnab]

Just under 3K of panels and the system can run the basics for three days of rain. That is pretty good for having only a car battery. That powers refrigeration, dishwasher with heated dry, pump, clothes washer, and hot water. And something to keep me alive, the battery must never drain down. Even the cloths washer has a 40 gallon tank and uses only hot water on all cycles. It is an extremely efficient system which is purpose built. I actually have nothing in common with the solar world except the panels. Most things only run when there is sun. Typical solar systems are inefficient and waste power. It does require some living adjustments but nothing inconvenient. It was an experiment just to see if it could be done as controls are mu field. I have all these manufacturers sending me free lithium batteries so I will be trying something new this year.

[peakbagger]

One thing to keep in mind is that installing a proper battery bank with a generator and inverter is going to save you a lot of fuel compared to running a generator. Sure if solar panels can be added that is icing on the cake but even an inverter based generator is going to slurp up a lot of gas idling when there is no power demand. Its far more efficient to run the generator to charge up the batteries and run off an inverter off the battery bank. If you envision cold season use you could also get a water cooled generator and heat water (via a heat exchanger) on the cooling system and even off the exhaust. That adds a lot of complexity but it can grab a lot of heat as long as there is use for it.

I live near an area with a lot of seasonal camps off grid and know several folks who went with batteries and they cut down hauling a lot of fuel into the camp. Some added panels but most just stuck with the batteries. They did it as much for the quiet as for the fuel savings. No matter how quiet a generator is, its going to get annoying.

BTW, give up any pretension on an electric stove, its an incredibly inefficient method when off grid. In a pinch an electric induction stove is lot more efficient. Same with water heating, if you go with propane as a fuel, you can put in a point of use heater or put in a heating coil with appropriate safeties on your heating source.