Solar Pathfinding

by Ben N on December 17, 2016

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The last two days, I was working with my friend, Kurt. Kurt and his wife, Monica, helped out on the garage a little while back when I was putting in the Pex tubing for the hydronic heat. Kurt mentioned that Monica had a Solar Path Finder. I asked if I could borrow it, and sure enough, the next day Kurt had brought it with him.

So, today, I got to use the Solar Pathfinder.

In essence, the Solar Pathfinder is an optical tool which makes a circular reflection of the trees, buildings, and other obstructions which may block your access to sunlight through the year. I used a Solar Pathfinder once before in a class, so I only needed a quick review through the manual before heading outside.

IMG_2445The device sets up on an included tripod. There’s also a bubble level to make sure it’s oriented nice and level. The first main thing to do is orient the Pathfinder due south. That’s pretty easy to do since there’s a compass built right in. It even accounts for magnetic deviation. If you are somewhere that True North and Magnetic North don’t quite line up, the compass can be adjusted to compensate for that. Where I am in the Midwest, the lines of magnetism point straight north, so I didn’t have to make any adjustments.

With the Pathfinder pointed straight south, I laid in place the piece of black paper that comes pre-printed with lines marking both the time of day and height of the sun at each month. (More than one diagram is included. I used the one that most closely lined up with my latitude.) On top of that, I placed the smoked plastic dome. Looking at the dome, I can see both the reflections in the dome AND the white markings on the paper UNDER the dome.

Looking straight down at the dome, the bubble level is right in the middle, and reflects straight back up. The edge of the dome is the horizon, with south at the top and north at the bottom. The left and right edges are the eastern and western horizons.

I outlined the trees by reaching under the dome with a white grease pencil. There’s space designed to reach through with the pencil.

Solar Pathfinder w graphics_largeAfter I had done that, I headed back inside to take a look at my tracing. The markings on the paper list what percent of the sun’s energy is in that hour during that month. I added up the percent of all the hours in which the sun was NOT blocked by trees. When the sun is highest in the sky – May, July, and June, trees only block the sun very early and late in the day. And when the sun is blocked, it’s only a very small percentage of the total daily sun energy. During those sunny months, the sun would be directly shining on my solar panels 92% of the time.

April and August give me 84% of the maximum solar energy.

Spring and fall, the numbers aren’t quite as good. A row of maple trees (belonging to my next door neighbor) blocks the sun in the late afternoon. Of course, a month like March will be a little better than September. In March, there aren’t any leaves on the trees yet, whereas in September the leaves haven’t fallen off yet. By October and February, I’m only getting 75% of the maximum solar energy.

In December, solar is at it’s absolute worst. The sun is just SO low in the sky that shadows stretch impossibly long. According to the Pathfinder, I might be down to as little as 25% of my maximum solar. The only upside is that all the trees in view are deciduous, (other than that pine tree right in the middle,) so at least there’s no leaves on them in the winter.  Then again, by February, that pine tree no longer reaches the garage. It’s also this same time of year that it’s completely possible for the solar panels to be simply covered with snow, producing essentially NO solar energy.

Solar-Pathfinder_sunnyThe important thing to remember is that MOST of the solar energy comes from the middle of the day and the summer season. So, do I have perfect solar access? No, I don’t. Ideally, you almost want to be in the middle of an empty field. I’m in a neighborhood, but at least I don’t have a great big tree right next to my garage! (Anymore.)

The other thing to remember is that I made this Solar Pathfinder tracing from THE GROUND. While my solar panels will be on the ROOF of the garage, I couldn’t figure out any convenient and safe way to do that at the moment, while we are in a brief pause between two snow storms. With the solar panels higher in the air, they will be LESS effected by the shadowing objects. If you look at the video I shot the other day, there’s clearly some times where shadows fall on the front of the garage (where the Solar Pathfinder was) but not on the ROOF of the garage.

The Solar Pathfinder didn’t really tell me too much new. I already knew that I’d lose some energy in the afternoons in the summer because of my neighbor’s tree-line. I also knew that the distant pine tree could reach the garage during those shortest days of the year. Using micro-inverters will help somewhat with shading in that only the shaded panel will stop producing energy. The others will keep producing power.

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Ben’s Garage: Winter Solar Access

by Ben N on December 14, 2016

The rough shell of the garage is now up! We got the roof boards and felt on just before the first major winter storm of the season. Since then, a cold front has moved through. While that DOES drop the temperature (single digits F. right now,) it also means CLEAR skies! It’s cold, but sunny!

So, how much sunlight will I ACTUALLY get on the solar panels on the roof of the garage in the winter? Not only are there fewer hours in the day, but the sun is SO low in the sky that shadows stretch unnaturally long.

The winter solstice is only a week away, and it was sunny out, so I thought I would test the ACTUAL solar conditions by filming a time-lapse video of the roof of the garage. I set up a step-ladder about 20 feet back from the garage and put a camera on it to shoot a still image every thirty seconds. What resulted was a video showing EXACTLY how shadows will fall on the garage roof.

DCIM100GOPROMost notable was the shadow of a pine tree in my front yard. That clearly sweeps across the garage roof. The upside of this is that it looks like it only swings past the lower third of the roof. I’m planning on installing 21 solar panels, in three rows of seven panels across. That shadow shouldn’t effect the top two rows of solar panels.

Secondly, I also noticed some deciduous tree branch shadows. I’m afraid to say that I really don’t know how much of a negative effect those shadows will have. They are thin and spread out.

Lastly, the largest and most distinct shading is very late in the day, when the shadow of the peak of my house infringes on the garage solar access. At first, just the peak of the roof reaches the corner, but then most of the garage roof ends up getting covered. The one upside of this is that it IS late in the day. It’s only about the last hour of daylight that the house shadow blocks the garage. By this time, the sun is so low in the sky that the solar panels would be producing minimal power anyways.

The main thing that I would like to point out is that this shading is the WORST CASE SCENARIO. Essentially, we are seeing how much sunlight shines on the garage during one of the SHORTEST DAYS, when the sun is about as LOW IN THE SKY as it ever is, and SHADOWS are LONGEST.

The rest of the year, there are many more hours of daylight, and the sun is much higher in the sky.

IMG_2418My plan for solar is to have 21 panels of the 60-cell variety in a grid of 3 rows of 7 in a portrait orientation. Each panel will have it’s own grid-tie micro-inverter. This will produce a faceplate value of over 5,000 watts. In my area, we average 4 to 4.5 hours of peak sunlight per day. This should produce a year-round average of about 600 kWhs of electrical energy. My running 12-month average for electrical use is 563 kWh. So, on paper at least, installing 5,000 watts of solar on my roof SHOULD bring me an annual NET ZERO electrical use! That’s for all the power of running my house AND charging an electric car.

Of course, if I can fit a little MORE solar than that on the roof, I’d certainly like to. That would help produce additional energy to offset converting the natural gas furnace and water heating to electric or adding an additional plug-in car in the future.

-Ben

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Ben’s Garage: Raise the Roof!

by Ben N on December 10, 2016

Today, we put the roof on the garage!

Planning was interesting, because the big weather forecast was for a large snowstorm to be coming in. Fortunately, it shouldn’t start until near the end of the day.

We weather was cold but clear as we got started – about 15 degrees F., but sunny. The first thing to do was build a scaffold to work from. Once we had the plank up, it gave us a place to stand to set our first piece of plywood, make sure it’s centered and squared, and then nail it.

IMG_2366All sheets of 5/8th” plywood run horizontal, and the trusses are on two foot centers. Steve and Josh stopped over, and it wasn’t too long until we were rolling right along, lifting sheets of plywood onto the roof and nailing them in place. We were really just nailing all the corners. Once all were in place, we went through with the nailing gun and put a nail about every six inches. That plywood ain’t going nowhere! (Laugh all you want, but there’s going to be a LOT of solar panels on this roof, and I want them to survive 100 MPH wind…)

(PHOTO: Josh takes a break to tune a guitar. I got a tiny used guitar for my daughter as a Christmas present. Josh plays, and was happy to tune it for me.)

Once all the plywood was down, we laid down the felt. This is actually a modern synthetic material. Instead of starting from the bottom, as would be typical, we started from the top and worked our way down. That way, we didn’t have to step on the felt. The roof was steep enough to merit cleats when we were laying down the plywood. Trying to walk up the roof on slippery synthetic material did NOT seem like a good plan. The only downside to this was that we needed to leave the bottom edge of each roll loose to tuck the next layer under as we retreated down the roof.

Try as I may, I personally wasn’t that useful on the roof. Ever since the notorious “Ben’s Ankle vs the Electric Motorcycle Incident of 2012″, my left ankle doesn’t flex the correct direction for walking uphill on roofs. Instead, I mostly kept busy lifting plywood to the roof, reloading the nailing gun, and moving lumber.

Once we completed the south side of the roof, we took a break for lunch (Sloppy Joes!) and to warm up.

Then, it was back to work, moving the scaffolding to the back of the building. Steve stuck around, but Josh had to go. Fortunately, I had Fred lined up for the afternoon, who had just showed up.

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The north side seemed to go a little quicker. All the minor adjustments on the south side make everything line up better on the north side. It was mostly just lifting plywood, flopping it down, and nailing it. The time lapse video ran out just before finishing the felt on the north side.

At the end, I was down on the ground, pushing lumber around and moving materials to INSIDE the garage. That’s right… INSIDE! With the floor already in of the upstairs, and now a ROOF in place, the garage is more or less closed up. (Not that it has doors or anything, mind you…)

As a finishing touch, Wayne and I strung up my single spare strand of LED Holiday Lights on the east gable end, which faces the main road. Instant Festive!

The other guys went inside for pie and coffee. As I finished sweeping the driveway, the first snowflakes started to fall. We had beaten the storm.

I tucked the car into the garage, hoping for plenty of snow, feeling perhaps a little smug that we got the roof on. Even without garage doors, or hydronic heat, or actual roofing, my car somehow seems a little warmer being in the garage, and under a roof.

Until next time, stay charged up!

-Ben

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Raising the Trusses!

by Ben N on December 3, 2016

This past Saturday, we got the Trusses up.

I was a little concerned about this. Each truss weighs over 200 pounds and is 31 feet long. We would need more than just my brother, my Dad, and I to do the job of lifting the trusses onto the roof, setting them in the proper place, plumb them, and make sure they stay there.

My work schedule has been crazy too. So, I was trying to dig up some spare bodies for the very next day while driving to and from work at night after having worked on the garage all day.

I put out a plea on Facebook and through as many phone calls and voice mails as bad cell connections in a car would allow.

The next morning, I wasn’t dissappointed. A flash-mob of friends were standing in my driveway in warm clothes and work gloves, ready to lift.

Starting the day was slow, as we had to figure how to set the very first end truss, including NOT letting it fall over the side of the building. We built some 16 foot long posts of two-by material and nailed those to the west wall. Those would keep us from lifting the first truss PAST vertical.

I had already assembled some scaffolding in the middle of the garage, spanned by an aluminum plank. We had plenty of ladders, although a motley mix of step-ladders, extension, and “gorilla”.

SAMSUNG CAMERA PICTURESSeveral of us would pick up the truss, flip it over (unfortunately the way the material was stacked didn’t suit the direction we were putting it up,) walk one end through the garage door opening, over the scaffold, to a guy on a ladder, to set on the north wall. Back on the south wall, we had to lift that end, slide the truss back to get it ON the wall, and then start sliding the whole thing west. One guy held the top point of the truss while walking across the plank. Once the truss was in proper position, we tipped it up, and temporarily nailed it.

Whew! Lots of work! We would only have to do that 15 more times!

The next several trusses were also a little odd. Just in from the west wall is where the pull-down stairs to get to the the upper level will go. So, that needed extra-wide spacing, and the trusses to be doubled up on either side of the opening. In the photo with all the trusses in place, you can see the extra-wide spacing on the left side.

After that, we were able to set the trusses on regular two-foot-centers. At this point, having lots of extra guys really helped. We were able to get into a slow but steady rhythm of placing trusses.

Once we made it to the middle of the garage, we had to change plans a bit. We needed SPACE above the garage to get the trusses in position. If we continued to place trusses, we wouldn’t have the room to get them up there. So, we started lifting them onto the walls, but stacking them all next to each other right in the middle. After that, we could start sliding them out, one at a time, into their proper positions.

IMG_2229Of course, we were also trying to keep these things straight and plumb as we went. We marked out measurements on the top of the wall, and measured between the points of the trusses before nailing temporary support boards to lock them in place. We also added temporary cross-bracing and some wood planks to walk on as we went.

By about 3 PM, we had all the trusses up and in place. We put away the tools and cleaned up, and then I had to head right out to work.

A big thank you to Shannon, Jack, Josh, Wil, Rich, Steve, Wayne, Jim, and everyone who showed up!

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-Ben

PS: After sweeping up all the nails, I did get to park the car in the garage!

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Putting up the Beam

by Ben N on December 2, 2016

The next big step would be install a header across the south side of the garage. This wall is almost nothing but doors. In fact, there’s so little there to hold up the roof that we needed a structurally engineered beam to span the entire south side!

IMG_2186This was done with a “micro-lam” beam. Essentially, it’s plywood. The beam is manufactured by laminating together layers of wood, just like with plywood, except that it’s designed for exceptionally long length. Micro-lams can be ordered in standard sizes from a full service lumberyards. The lumberyard delivered the beam to my house. It’s actually TWO pieces of wood. That’s a good thing, as HALF the thickness of the total beam is already about as much as three guys can lift.

We first built out a few studs (vertical 2×4′s) that were the height of the wall, minus 16 inches. The beam itself is 16″ tall! We also put in a block on each end right BEHIND where the beam would go. That kept us from overshooting, lifting the beam too far, and dropping it into the garage!

Next, we brought over the one micro-lam and cut it to the correct length (the order was for the closest stock size to what we needed.) Using some scaffolding, we had a good place to stand. We got one end of the beam onto the one scaffold, then the other end on the other scaffold. With one guy in the middle on a ladder, we lifted the micro-lam into place, then nailed it.

We repeated the process with the second micro-lam, made sure everything was straight, then added a 2×4 top plate to it. The two laminates were screwed together with some fancy little screws designed just for said purpose.

IMG_2202Next, we needed to sheath the wall. The other three walls have 1/2″ OSB sheets. It’s relatively cheap/sturdy, but for the front wall we would need something a little better. For the south wall, we used full sheets of 3/4″ plywood, cut into “T”s and “L”s to fit around the doors. This acts as cross-bracing in the east/west direction.

All together, this wasn’t a real long day, but it was certainly work to get the beam installed!

We needed to get the trusses up onto the roof the next day. Each one weighs over 200 pounds. (Check out the blog about when the trusses got dropped off to see how big they are!) I had to work in the evening too. So, I put out a desperate call for help on Facebook and started making as many telephone calls as I could driving to and from work for the evening. But would people show up? Crossing my fingers!

NEXT TIME: Lifting the trusses.

-Ben

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