Independence from the electrical grid is both a learning and conversation component of Green Woodlands. For this facility we will be generating hydro-electric power from the pond and stream nearby and solar-electric from the sun. Being completely self sufficient and not being dependent on the electrical grid sets the stage for just about every building system we will employ.
No artificial lighting is the best lighting so we spent a lot of design time with "day lighting" or using the sun to light our building as much as possible. The big question we asked is do we need to "turn a light on" during the day or is there sufficient light coming from outside so we do not need to. This is a balancing act because we also do not want excessive thermal gain during the warmer months or harsh glare from the sun.
The sun does eventually go down so we do need to turn lights on eventually. Our tastes run towards antique style lighting and Energy Star Certification wasn't around in the early 1900's so we contracted with a local company called Conat Custom Brass whose artists and engineers recycled antique light fixtures and retrofitted them to use only compact florescent lights for us. This gave us the modern Energy Star Certified internal components, recycled antique lights and kept the business within our local community.
All Electrical Wires in Conduit
Commercial buildings usually run their electrical wires in conduit but that is not normally done with residential houses. On the other hand we are building the Barn House to last 200 years. Running the electrical wires in conduit up front will prolong the life of the electrical wires many fold plus make it exceedingly easier and less costly to rewire or add to the electrical wiring design in the future. The other issue that will be mitigated with running the wiring in conduit is there is debate over the health effects that EMF waves from electrical wiring has on us. The conduit will add another shielding layer to inhibit EMF waves. Another benefit is the fire safety of having the electrical wiring protected by conduit.
No Phantom Load Electrical Design
You would be amazed at the electricity use of our modern appliances when they are turned off. That little trickle of electricity to keep that small LED light or clock on your dishwasher, washing machine, dryer, stove, stereo, microwave, trash compactor or TV adds up quite a bit. In order to turn these phantom loads off you either have to unplug the appliance or have an electrical switch to turn it off. This no phantom load wiring adds a bit of complexity to your electrical design and more electrical switches but when you measure every watt of electrical use it is the only way to say no to these phantom users of electricity.
As a final and last resort we do have a propane back-up generator. If we have to use it then we have not achieved out goal. To say it a bit more frankly and hold myself and others accountable, we have failed if we have to resort to using fossil fuels to operate this building for heating or electrical needs.
Solar Electric System
Invisible Solar Panels
We have been experimenting with solar panels for about eight years now and quite frankly the modern glare of glass panels just does not blend in with the wooden rustic environment and the connection to nature we are looking for. Our goal was to have a solar array that would power all the modern electrical conveniences in a regular house but we did not want to see it. We have used a flexible photovoltaic laminate product from Uni-Solar, this product actually rolls onto a metal standing-seam roof and in our application it is virtually invisible.
Above is a picture of the Barn House around the first week of September 2007. The chimney is under construction but the solar panels are on the roof. Can you tell which part of the roof has the solar panels? We have asked many people that come by the property and so far no one has been able to tell where the panels are.
The selection of the color of the standing seam roof was critical to blending in with the Uni-Solar Photovoltaic Laminate panels. On the Barn House roof we chose Matte Black manufactured by Englert Inc. to match the solar panels.
These Uni-Solar panels also come in specific sizes and are rolled into the standing seem panels. Initially we have only covered the sugar house roof section of the Barn House with panels. At a later time we may cover the rest of the roof but we wanted to insure that the solar panels were invisible. The standing seam roofing width needed to be 16 inch wide in order to fit properly with the 15 1/2 inch solar panels. The sugar house roof section has 24 panels of Uni-Solar's part number PVL-68. These Panels are 9 food 4 inches long by 15 1/2 inches wide so the sugar house roof was made to fit these perfectly. The panels are rated at 68 watts each so 24 panels gives us 1,632 watts of power. This is not quite enough for the house so we also put panels on the small barn that is adjacent to the Barn House.
The Barn House (and thus the panels) face 45 degrees east of true south so that will diminish the effectiveness of the panels to a small degree. The roof pitch is 8/12 which is good for shedding snow and effective of the solar panels as well.
Small Barn Solar Panels
The existing Small Barn was equipped with 17 Uni-Solar PVL-136 panels. These panels are 18 feet long by 15 1/2 inch wide and are rated at 136 watts each, thus giving us 2,312 watts on this roof. This roof faces 35 degrees west of true south so it also is a bit diminished but does catch more of the sun during a different time of day than the Barn House.
The total for both roofs are rated at 3,944 watts but with reductions lets call the combined system 3,800 watts of 3.8kw.
Now the big question is this enough solar capacity to power the complete house? We have done calculations and shading studies especially during our long winter months but the bottom line answer is maybe, and we think so. We do have a backup generator that can recharge out battery bank in a few hours but that will use propane which we do not want to do. Time will tell and we can add more solar panels to the rest of the roof if we really see the need to.
Above is a picture of the Small Barn with 17 panels on the stand seam roof. If you look closely on the right hand side there are a couple of partial roof panels that do not have solar panels on them. We also made the mistake of putting a Charcoal Gray color from Englert Inc which was recommended as matching the solar panels but as you can see it does not. In order to blend this in a bit closer we will be taking the Uni-Solar panels and cutting and pasting it to the roof section that does not match. For right now, it is a good example of why it is important to match the color a bit better like we did on the Barn House.
Shading on Panels
You will notice in the Small Barn picture above there is an ash tree on the left of the roof that at certain times of the day does shadow the panels. This tree will be removed and used for building material for the Barn House. The Barn House also has the shading on the chimney which during certain times of the day will cast shade on some of the panels. The other shading that will affect the panels is New England weather especially the winter. California or Arizona sun we do not have and it seems to feel that we can count the sunny days during the winter on our fingers and toes.
The Uni-Solar panels have what is called bypass diodes between each cell. This means that if a cell should stop working due to shading or damage, power will bypass the shaded cell and the panel will still produce close to the rated output. We are told that the traditional crystalline solar panes almost shut down when they are partly shaded. We have a number of the crystalline panels on a solar wagon and if we shade a small section with out hand it greatly reduces the power generation but not so with the Uni-Solar panels. Okay California, this is not a big deal for you because you have sunshine 300 days a year but in New England we have what are called clouds and they bring rain and snow which gives us more character in out weather. These clouds also create shadows on our solar panels.
Connecting the Two Buildings with Solar Panels
The Small Barn is about 200 feet away from the Barn House so we needed to run a cable from the Small Barn solar panels to the inverter in the lower level of the Barn House. Well, this does not sound like a big deal but apparently the longer the cable run, the thicker the cable needs to be so it does not loose the energy along the way. This cable was close to 700 pounds and we actually used a tractor to help pull it through the pipe that ran between the buildings.
Wiring of Solar Panels Under the Ridge Cap
Each of the solar panels on the Small Barn and the Barn House needed to be wired under the ridge cap of the standing seam roof and this ridge cap needs to be installed very carefully with close attention to Uni-Solars installation instructions.
Electronic Components for Solar System
Our solar consultant, supplier and installer , GroSolar, recommended Outback Power Systems to supply most of the "stuff" that does between the solar panels, the batteries and our electrical wiring for the building. Staying with a consistent company for the most of the components facilitated compatibility and serviceability later on.
In our prior solar learning experience we initially purchased four deep cell batteries with which after a number of years we realized we needed more power and to add more batteries. I wanted to double the battery bank to eight. Well, guess what? I was told that our old four batteries would bring the strength of our new batteries down so it was recommended that we purchase eight new batteries and find a home for the older, not as robust old batteries. Ouch! This time we doubled the amount of batteries we wanted to go with right up front and went with 24 Surrette Rolls 2V, 1850Ah deep cycle batteries. These batteries weigh 204 pounds each and cost between $500 and $600 each.
Next trick is to store all 4,896 pounds of these batteries and take care of them so we get a good return on investment.
An important aspect of the battery box is an installation of a fan that will vent outside of the building. This needs to be completed separate from your building ventilation system. The fan is set to automatically go on when the batteries are charging and subsequently off gassing.