Designing PV for snowy climate

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Are Solar Panels Usable in Snowy Climates?

By Erin Cassidy, Accuweather.com Staff Writer

January 11, 2014; 10:00 AM

With a new year beginning, installing solar panels is a great way to fulfill environmentally-friendly resolutions.
However, for those living in wintry climates, snow accumulation may pose a problem.
Joshua Pearce, associate professor at Michigan Tech University (MTU), said, "If snow is completely covering the panel, you are obviously only going to get the amount of energy out of the panel from the amount of light that is able to pass through the snow."
"Even having a relatively small amount of snow on top of a given panel can radically reduce the amount of energy output for your entire system," he said.
Due to these issues, research is currently being conducted whether solar technology is useful in wintry climates.
Solar panels at the top of a mountain. (Credit: Flickr/SteFou!)
The projected losses could affect energy costs for all homeowners using solar power, but only significantly for ones that rely entirely on solar power and are not connected to the traditional electrical grid.
For the vast majority of homes and businesses that still remain "on-the-grid," the financial impacts are minimal but the energy losses still pose questions to enhance optimal usage.
Research being conducted in Michigan, Colorado and Washington by MTU and the engineering firm DNV GL is designed to test the energy output for solar panels with varying levels of snow coverage and other factors such as "racking" (the accumulation of snow at the bottom of a panel if the snow can't slide off naturally) and the angle the panels are tilted.
When the study is completed, Pearce is confident that, "Everyone, both [solar panel] designers, people that are funding systems and everyday homeowners [should] have the ability to look at your weather data for your area and predict, with very good assurance, what your snow losses or snow gains would be."
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The research is also examining the positive effects of a snowy climate on solar panels.
"When snow is on the ground and the panels are clean, the snowy surface basically acts as a mirror and you can get higher output," Pearce said. "In many cases, you end up with a small boost because of the reflection off the snow."
Pearce describes several methods they have used to increase the efficiency of panels with snow accumulations.
Solar panels are a cost-efficient form of alternative energy, with an overwhelming percentage of new systems being installed in tangent with the traditional electrical grid.
As long as a structure is connected to the power grid, electricity will not be interrupted when snow accumulation makes solar energy unattainable.
With continued research and installations, solar power remains a viable option for Americans hoping to utilize reusable energy.

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Tips for Solar Power Users in Snowy Climates

Bounce a tennis ball off snow-covered panels.

Homeowners who have rooftop solar panels installed can surprisingly increase the energy output by bouncing a tennis ball off the snow-covered panels. The small divots created by the tennis ball help begin the snow shed process and allow sunlight to reach the modules and begin converting energy.

Install solar panels at the largest angle possible.

A higher angle lessens the accumulation of snow on top of the panel. "Everyone that is in a very snowy place, like in northern Michigan, should be aggressive in your tilting angle. So if you have a decision to make between something like 30 degrees or 40 degrees, it's better to go 40 degrees," Pearce said.

Don't set up panels in a way that allows snow to gather at the bottom.

Installing panels in a way that allows the snow to fall freely from the array greatly reduces the impact of snow. When snow slides off the panel at an angle and gathers at the bottom of the module, the losses can significant. "In those cases, when you have a very low tilt angle and a dam [of snow], you can lose all of the solar energy associated with the winter," Pearce said.

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Winter Composting, Fish Emulsion, and more

http://www.doityourself.com/stry/how-to-make-organic-fish-emulsion-for-your-garden#.UsJTG7RGTRo

http://www.organicauthority.com/organic-gardening/composting-over-winter-for-gardening-success-in-spring.html

Firewood 101

Copied from Before its News

Thursday, December 19, 2013 17:45

0

(Before It's News)

Collecting firewood is more involved than just cutting trees down, cutting them up and stacking them to be burned in a wood stove.  Here is some very important information to follow when gathering firewood.

1. Burn only well seasoned firewood
Seasoned firewood comes from two  sources.  1. Trees that are dead and standing or on the ground. (Needles/leaves have fallen)  If the bark is partially or completely missing this usually indicates that the tree is probably dry/seasoned.  However, notice if part or all of the tree has deteriorated beyond usefulness.  Standing dead trees can be dryer than fallen dead trees.  2.  Green/wet wood that has been cut to the proper length for a particular stove, split, covered and allowed to air dry for at least 1 year or more.  It may require more than a year to dry if the wood comes from a region that receives a large amount of precipitation per year resulting in wood that contains more moisture.  Why should unseasoned wood (green/wet wood) not be burned in a wood stove?  When unseasoned firewood is burned the moisture in the wood becomes vaporized and is expelled up the stove pipe.  As the vapor travels farther away from the fire it begins to cool and collect on the inside of the stove pipe, solidifying and forming creosote.  Under certain conditions the creosote can ignite and become a dangerous “chimney fire”.  During a severe chimney fire a steel stove pipe can melt down causing the house to catch fire. Also a mason chimney/chase can get so hot it will crack and allow flames to lap thru catching the attic/roof system on fire.
2. Have at least a 2-year supply of firewood on hand
What if the firewood cutter in the family got sick or broke a bone?  Or, what if there was an unforeseen emergency, whether national or global, that prevented one from collecting firewood?  Wouldn’t it be wise to have at least a 2 year supply of firewood on hand?
3. Save trees on your property for times of emergency
According to a Storey Country Wisdom Bulletin titled “Woodlot Management”, one needs a minimum 5 acres of trees to maintain a renewable supply of firewood.  This  depends on the climate of the area, the size of the house, how well it is insulated and the efficiency of the wood stove.  What if you don’t have a minimum 5 acres of trees available for firewood on the property?  It would be prudent to collect at least a 2 year supply of firewood from other sources until those sources are no longer available. Then and only then start using the firewood on your own property.
4. Know your trees
Not all trees are created equal.  Some species contain more  heat units (British Thermal Units…BTUs) than others.  This is to say that some species will give off more heat per pound of wood, burn longer and leave less ash than others.  Each region of the country usually has at least one of these species of wood.  You must make yourself aware of which is the best in your region.  The following table shows various species of wood and their corresponding list of “Available heat at 50% efficiency in millions of BTUs. (Most wood stoves)”
Species                                  Millions of BTUs
Hickory                                         13.8                               
Apple                                            13.2
White Oak                                     12.8
Sugar Maple                                  12.0
Red Oak                                        12.0
Beech                                           12.0
Yellow Birch                                  11.8
White Ash                                     11.8
Hackberry                                     10.4
Tamarack                                      10.4
Paper Birch                                   10.2
Red Fir                                         11.1
Cherry                                          10.0
Elm                                                9.8
Black Ash                                        9.6
Jack Pine                                         8.5
Norway Pine                                    8.5
Lodgepole Pine                                8.8
Hemlock                                         7.9                           
Black Spruce                                   7.9
Aspen                                            7.3
White Pine                                      7.2
Balsam Fir                                      7.2
Grans Fir                                        8.4
Cotton Wood                                   6.7
Basswood                                       6.7
White Cedar                                    6.1
            Compiled from information from the Univ. of Minn. and the Univ. of Idaho.
5. Estimating the number of trees needed
Once it is established how many cords of wood is needed to heat your dwelling for a season, the following table can be used to estimate how many trees will need to be cut.
                                     Table for Estimating Cords per Tree
DBH             Cords/tree           No. Trees to Make a Cord
                                                                                                           
  4”                0.01                                   67.00                      
  6”                0.04                                   23.00                       DBH = diameter outside bark
  8”                0.09                                   10.50                                 at 4.5’ above ground.
10”                0.17                                     5.80 
12”                0.28                                     3.50
14”                0.41                                     2.40                      Univ. of Idaho Extension Service
16”                0.58                                     1.70                                             Data.
18”                0.70                                     1.30
20”                1.00                                     1.00                  
22”                1.20                                     0.82                      Cord = stack of firewood
24”                1.50                                     0.67                                4‘ W X 4‘ H X 8’ L    
26”                1.80                                     0.57
28”                2.20                                     0.46
30”                2.50                                     0.40
6. Finding the right kind of firewood
While looking for a particular species  in a forested area try to find a stand of trees of that species. The possibility of finding a dead tree of that same species will be increased. If cutting firewood in a National or State forest be sure to have proper permits with you and know the regulations.  Also if cutting wood in a National or State forest it is best to be one of the first in the area you are looking thru.  This can assure you of being able to find good firewood near the road you are driving (“Low hanging fruit”) which makes it easier to get the firewood into you truck.
7. Tools needed
Chainsaws – Husqvarna and Stihl are two of the best on the  market.  Dealers, parts     and service are readily available in forested regions of the country.  Both brands make chainsaws in three different grade levels:  1. Professional grade  2.  Farmer/Rancher/Mid-grade and  3. Homeowner grade.  It is recommended to purchase saws only in the top two grades of these two brands. 
A Stihl “Farm Boss” with a 20” bar is a mid-grade saw that should be durable enough to cut a persons supply of firewood, and then some, for years to come.  I believe it is one of the best saws for the money.  I have owned four Stihl chain saws over the past 25 or so years and have been very satisfied with every one. 
If you have back problems or are in your golden years I recommend a Stihl
Pro MS 261 with a 20” bar.  If this saw is taken care of it should cut all your firewood and then some for many years.  It will do the same work as a much larger saw only a little slower.
Why a saw with a 20” bar?  A person doesn’t have to bend over as far when de-limbing a downed tree and of course it can cut larger trees.
I recommend mixing the manufactures brand of oil in the chainsaw fuel.  I also recommend using non-ethanol fuel (If it is available in your area) even if it comes only in premium grade.
Crosscut Saw -  If your chainsaw breaks and for what ever reason it is impossible to get it fixed at the time, a sharp crosscut saw is an excellent back up.  A good place to find old crosscut saws is flea markets and yard sales etc.  If an old saw isn’t missing teeth, doesn’t show much ware and isn’t pitted with rust to deeply they can often be restored back to good working order.  New crosscut saw can be ordered from www.traditionalwoodworker.com.

Ax, Maul, Steel Wedge, Sledge Hammer etc. – Snow and Neally manufactures some of the best axes for the money.  Forged steel heads and tight grain New England ax handles enable these tools to have a limited life time warranty.  Axes can be used to de-limb downed tress. They can also be used to cut fire wood if all other cutting tools fail. Mauls are used to split “rounds” of fire wood.  If the rounds are too large for a maul to be effective steel wedges driven with a sledge hammer will split the large rounds down to a size where the faster splitting maul can be used.  Good quality mauls, steel wedges and sledge Hammers can usually be found from local hardware stores or logging supply stores in forested regions of the country.
Peavey – What is a peavey?  A peavey or peavey hook is a logging tool consisting of a handle, generally from 30 to 50 inches long, with a metal spike protruding from the end.  The spike is rammed into a log, then a hook (at the end of an arm attached to a pivot a short distance up the handle) grabs the log at a second location.  Once engaged, the handle gives the operator leverage to roll or slide the log to a new position.
Log Lifter – A log lifter is a device similar to a cant hook (a cant hook is similar to a peavey except it has a blunt end where the peavey has a metal spike) and has a short metal leg and foot attached to the handle on the opposite side from the hook.  After the hook is forced to snag the log the operator pushes down on the end of the handle which in turn rolls the log up onto the metal leg/foot lifting the log off the ground.  This makes it possible for the log to be cut without the chain saw touching dirt which can dull the chain.  It also raises the log off the ground keeping the operator from having to bend down so far to cut the log.
Snatch Cable and Snatch Block – If a desirable tree is dropped where the end of it falls within 90’-100’ of a road, a snatch cable can be used to pull it out to the road where it can be cut (“bucked”) into proper length rounds. 
This is how it works. The downed tree is de-limbed. Using either a short chain or choker cable one end of the snatch cable is attached to the end of the downed tree closest to the road.   The other end is connected to a vehicle on the road which drags the tree out of the forest.  If the only area where the vehicle can be driven, while pulling the snatch cable, is on the road a snatch block is then used.  The snatch block is a heavy duty pulley which is attached to a substantial tree next to the road.  The cable is run thru the snatch block and then connected to the vehicle.  The vehicle is then driven slowly down the road pulling the cable thru the snatch block which pulls the tree out to the road.
8. Safety
Basic rule of thumb:
          A. NEVER CUT FIREWOOD WHEN YOU ARE TIRED! 
          B. ALWAYS HAVE ANOTHER PERSON WITH YOU WHEN CUTTING!
Other important safety measures:
Chainsaw Chaps and Steel-Toed boots – Most accidents that occur while using a chainsaw cause injury to the body from the waist down.  Therefore it is most important to use chainsaw chaps and boots with steel-toed shields.
Protective Helmets – Before cutting a tree down always observe the upper part of the tree for the presence of a “widow maker”.  A widow maker is any upper part of a tree that is so fragile from decay or some previous damage that it could break and fall causing serious injury or even death to the tree cutter below. This is why it is very important to wear a helmet for protection when cutting a tree down.
Ear Protection – The loud sound of a chainsaw WILL cause the loss of hearing to unprotected ears.  Therefore it is imperative to wear some kind of ear protection devices.  Ear protection devices can be purchased from home improvement stores.  Ear protection devices used while shooting firearms is a very good way to protect ones ears and can sometimes be priced quite reasonably at stores that sell firearms.
Eye and Face Protection – Wood chips being thrown while cutting with a chainsaw can
cause injury to the face and eyes, even loss of eye sight.
There are chainsaw helmets that have face, eye and ear protection devices attached to them and are usually available at chainsaw dealers.

Northern Illinois Farm Blog with a member share

http://all-natural-mama.blogspot.com/

Grow lights for plants indoors

Excerpts from
http://www.kulekat.com/led-home-lighting/do-led-grow-lights-work.html


Photosynthetically Available Radiation (also called Photosynthetically Active Radiation and abbreviated to PAR) defines the spectral band between 400 and 700 nanometres (nm) as illustrated in the diagram where plants find light suitable for photosynthesis.
The standard unit of measure for PAR is µmol (micromoles) per square meter per second which gives the photosynthetic photon flux density (PPF or PPFD) – essentially how much light is hitting a given area. Where lumens per watt are used to determine the efficacy of regular lighting (i.e. intended for humans), PPF holds sway in horticulture.

How much light do plants need?

Now generally speaking, the more light the better where plants are concerned; however there is a distinct point beyond which they are unable to make further use of extra light. This is rather boringly called the Light Saturation Point and for your average plant this is around about 500 µmol/m². For comparison, the maximum amount of PAR available on a clear summer day is 2000 µmol/m².
Subjecting plants to light in excess of their particular saturation point (this obviously varies for individual species) is not only wasteful but in fact counter productive as they will actually grow less well. An easy way to adjust the PAR is to simply alter the height of the lights above the plants.
For example, the saturation point for lettuce is about 300 µmol/m² and a typical 130w LED grow light can deliver between 200-1400 µmol/m² as the distance is varied from 3 feet to 6 inches. The optimum height for growing lettuce would thus be at about 2 feet.
To sum up then, what plants require for healthy growth is light that radiates at four specific wavelengths (two types of chlorophyll times two absorption peaks each). To be technical, chlorophyll “a” absorption peaks are at 430 nm and 662 nm, and chlorophyll “b” sits within “a” at 453 nm and 642 nm.

Likewise, because LEDs accurately target the wavelengths preferred by plants they both don’t need to be and in fact don’t seem so bright to us, even though they are actually delivering a greater amount of “useful” light.
That perception is further bolstered by the fact that HIDs emit a lot of light in the green/yellow part of the spectrum which increases their perceived intensity to the human eye (unlike plants we favor light around the 550 nm mark). But the fact is that they are just wasting all this additional light since it is of little benefit to plant life.
If we take a 400w HID as an example, about 260 watts of that will actually be completely outside the Photosynthetically Available Range (PAR) so at least 65% of the light (and the energy used to produce it) is completely wasted.
So with less than 40% of the light generated by HPS and MH lamps being absorbed by plants, and barely 10% of the electricity you pay to run them being actually converted into light in the first place this is not looking promising for conventional lighting. On these figure about 4% of the input energy ends up doing some good for the plant (it’s not quite that bad to be honest, but it’s fun to push the data around to draw extreme conclusions).

spo--you can use combinations of blue and red LED or it might be cheaper to just use a full spectrum LED and get the benefit of a SAD light box.

 Light intensity and distance
It’s worth also reiterating here that because LED lights have a very low heat output, the Inverse Square Law of light (mentioned above) plays to their advantage. Let’s say you have a set of grow lights positioned two feet from your plants that delivers, for the sake of argument, 400 lux (the intensity of light per square metre). If you halve that distance to one foot then the light delivered will be equivalent instead to 1600 lux – a massive increase in light density without any additional expenditure.

To be at all effective, each individual LED should consume at least one watt of power. Below this level there is insufficient penetrative power. There is a balance to be maintained between overall light coverage and individual light intensity. Consider for example replacing a 50w halogen lamp with 10 x 5w lamps – the intensity is simply not there.
So if (to use an example that may be familiar to some) a panel is rated at 13.8 watts using 225 LEDs then you can easily calculate that each one is 0.061 watts – about 16 times below the minimum threshold, or equivalent to using a 6w light bulb in place of a 100w one

To go back to our Edison 1W LED by way of example, the same Edixeon S in the form of a 3w bulb is indeed brighter at a total of 85 lumens, but the lumens per watt figure is one third that at just over 28lm/w. Put another way, 3 x 1w LEDs gives a total of 150lm (3*50lm)which is a lot more light than 1 x 3w LED outputting 85lm. The same effect is observed as the wattage increase through 5 and 7 watt LEDs.

But you can compare what is used in any given product with a respected standard such as this Edison High Power 1w LED. Note that this lists luminous flux for LEDs emitting light at different wavelengths, so we can easily see that at 620~630nm we get 50 lumens (per watt, obviously since this is a 1 watt lamp).

Many 1st generation LED grow lamps were bi-band (just red and blue) which experience has shown to be insufficient for most plants. Although these two wavelengths satisfy the bulk of a plant’s needs, most still require trace amounts of light from other portions of the spectrum. However, many growers reported good results even with these early models – once considered state of the art and yet still the subject of heated debate – plus ça change…
More modern (so-called 2nd generation) system are tri-band and incorporate an orange component and there are now 5 band lights that match both chlorophyll absorption peaks in the red and blue zones plus orange.
You should be looking for anything above 90 watts, so an LED grow light 120 watts or more should suffice depending of course on your specific requirements and situation. The reason incidentally that it is common to find LED grow lights 120w advertised online is that this is approximately equivalent to most standard 400w HPS setups (in much the same way that in the world of domestic energy saving light bulbs a 6w LED is shorthand equivalence for a 50w halogen lamp).

Winter gardening Blog from Minnesota

http://www.milkandhoneyfarm.com/garden/winter.html