Off the Grid Living (General)

[Aggie]

Questions / Comments for Zachary:  You mentioned that microhydro helps making up for inadequate solar panels in the winter.  I did notice on your site that you've dealt with the odd extreme freeze-up, which seems like a bit of a limitation for winter use (could be overcome with insulation and a bit of heating, I suppose).

I'm in Canada, and hope to get off-the-grid in British Columbia soon (Southern Interior).  If Oregon presents challenges for PV electricity generation, I'm sure BC would be worse.  My biggest concern with microhydro is that seasonal flow tends to decrease in the winter - the Interior does not get the winter rains that the Coast does - and that freeze-up might make it unfeasible in the winter.  This doesn't stop hydro from being a good, cost-effective add-on for the warmer months, particularly spring, and possibly even a primary electricity  generator at the right site.

How much does your PV production drop off in the winter? I suppose what I'm really asking is 'What % of your electricity comes from each source during different times of the year?'


We've been pondering a bit on wood-fueled electricity generation too, which would be a good way to get some electricity from a necessary heating system, if it can be done on a small, cheap scale.

Feel free to add to this thread on other aspects of off-the-grid living!

[Bob in a quantum-state-of-faith]

I'm not certain, but I think the winter drop-off of PV panels is due to the sun being lower in the horizon-- obviously, this only effects northern hemisphere*, and at higher latitudes.

I've not heard of PV panels' efficiency being adversely affected by low temperatures-- after all, they use these on satellites up in the "cold" vacuum of space.

The other thing about winter, is there is often less sunshine (i.e significantly more cloud cover) than typical summer weather.  PV's are directly affected by cloudy days.

(I was just listening to a Science Friday podcast about this very subject, today, as it happens)


_____________

* okay, I realize that southern hemisphere has winter, too-- but it's not in the same months as up here. 

[Aggie]

I'm a lot further north than most of you.   The Interior typically has more cloudy days in the winter, often due to inversion, but maybe not as bad as the Coast, which I'm guessing is where Zach is - the rain gives it away.

Right now in Cowtown, the sun rises in the southeast, not the east. I hadn't been home to see a sunrise from my apartment in about a month, and the shift was rather shocking.

[Sibling Zono (anon1mat0)]

Actually if your panels are properly aligned you shoud get as much energy in light hours, the problem is that there are few of those going up (at the solstice you'd get what, 8? 6 hours?).

[Aggie]

Something like that - right now we get daylight from 8 till 5, much less direct sunlight than that.   Don't forget the length of passage through the atmosphere is much greater, so the light intensity (and therefore energy) drops as well, even if you're aligned perfectly.

[homebrewhydro]

Questions / Comments for Zachary:  You mentioned that microhydro helps making up for inadequate solar panels in the winter.  I did notice on your site that you've dealt with the odd extreme freeze-up, which seems like a bit of a limitation for winter use (could be overcome with insulation and a bit of heating, I suppose).

Yes being on in the coast range we have the odd snow and freezing but nothing like you'd have east of the Cascades or interior of BC.  So that is an issue.  You could bury your pipes and run the turbine in a shed or something like that.  But it's an issue for sure for you guys in the cold.

I'm in Canada, and hope to get off-the-grid in British Columbia soon (Southern Interior).  If Oregon presents challenges for PV electricity generation, I'm sure BC would be worse.  My biggest concern with microhydro is that seasonal flow tends to decrease in the winter - the Interior does not get the winter rains that the Coast does - and that freeze-up might make it unfeasible in the winter.  This doesn't stop hydro from being a good, cost-effective add-on for the warmer months, particularly spring, and possibly even a primary electricity  generator at the right site.

Less water in the winter is a strange one for me   I assume it's all in the ice and snow which melts in the summer huh?  That is a problem for sure.  The vast majority of people won't have the right environment for micro-hydro -- you require either a large amount of water and/or a high head (the elevation difference between the intake and the turbine).  I have 40 acres on a big hill on the oregon coast where it rains a lot, so it just turns out to be a good spot.  Actually I need more water -- my feeder stream isn't all that big.  I have a big creek on my place but there are a lot of issues with tapping that. 

How much does your PV production drop off in the winter? I suppose what I'm really asking is 'What % of your electricity comes from each source during different times of the year?'

My PV drops off probably 70 percent, but that is due to the fact that my land is on the wrong side of the hill

I have a north/north-west slope with a lot of timber so in winter my solar panels are occluded by shade for the first part of the day in Winter.  And it's always cloudy and raining, being Oregon.  Much like Van or Seattle the whole West coast is kind of like that.

We've been pondering a bit on wood-fueled electricity generation too, which would be a good way to get some electricity from a necessary heating system, if it can be done on a small, cheap scale.

I've heard a lot of discussion about wood fired power and several people have attempted such systems.  The classic would be a steam powered engine of some kind, which if you do the math, doesn't scale too well to smaller applications.  It can also quite dangerous.

The other way is to use what are called: Thermoelectric Generators

I looked into these several years ago and at the time, the price per watt was crazy high.  I know a guy in Alaska who scored a nice military surplus unit for next to nothing but at the time it didn't seem practical unless you had serious $$$

But the technology is way cool.. you just put these solid state 'bricks' on your wood stove and power comes out.  Might be worth doing more research into this, if the price has come down.

Just doing a search I found
http://www.tegpower.com/products.html

which has a 50 watt unit for $500 US.  My multi-meter has a laser thermometer so I shot my fire place (which is running around medium heat) and hit 160 C -- which according to the site would yield around
30 watts of power. 

That's like 16 dollars a watt to make that power.  OUCH!  You can find solar panels for around $2 a watt.  Then factor in the chainsaw gas, the labor and the trees and it's a pretty expensive way to make power.  You can imagine if you needed to make 1000 watts it would add up fast.  But you could easily use the fireplace to make hot water for general use.  There are gobs of methods for doing that kind of thing.

Have you run across any other methods for extracting electricity from wood heat? I'd love to know about it !


I don't know if you are familiar with  usenet but there is a group alt.energy.homepower where a lot of engineers and power geeks building various things hang out. It's a good resource for bouncing ideas around.

One of the guys there Morris Dovey see ( http://www.iedu.com/DeSoto/Fluidyne/ ) has been developing a solar fluidyne engine -- which basically uses temperature differential in liquid to move a piston (and thus create mechanical potential which could be used to run a turbine).  No reason why heat from a fire couldn't be adapted to something similar maybe.  Might have to ask him about that .. i could use more power


As for potential hydroelectric power the people at Energy Alternatives in Canada have a very slick win32 application that lets you plug in a bunch of variables (head, pipe size, water flow etc) to see how much power you could expect to produce.  It's free and fun to play with .. helped me a lot in designing my system:

http://www.energyalternatives.ca/content/Categories/MicroHydroInfo.asp

I guess the other big question is: how much does the wind blow where you are?  I'm up in the hills just far enough off the coast that I don't have the regular wind (unless a storm hits), so it's not practical to put up a wind turbine, but I know in eastern Oregon/Washington area they get plenty.  Maybe that would work for you?? 

Wind turbines are proven technology -- no fancy dancy solid state fire bricks or Desoto fluid engines needed

best of luck with your power generation -- it's pretty cool if you can make it work.  I'm typing now on power made by my little creek

-zachary

[homebrewhydro]

I'm not certain, but I think the winter drop-off of PV panels is due to the sun being lower in the horizon-- obviously, this only effects northern hemisphere*, and at higher latitudes.

I've not heard of PV panels' efficiency being adversely affected by low temperatures-- after all, they use these on satellites up in the "cold" vacuum of space.

Exactly. PV panels actually increase in efficiency as they become cooler. Some people have used those little micro-sprinklers to cool panels in summer to gain those extra few watts.  I don't remember the equation off the top of my head but heat does make a big difference.  The bummer is in winter there isn't as much sun and like you say.. overcast and drizzle isn't so great for making power via PV