Category Archives: Environment

Feb 09 6 comments
Electrical, Environment, yard

Installing our Photovoltaic System, part V

Inspections.  There are three inspections.  When scheduling the inspections,  thou shalt count to three, no more, no less. Three shall be the number thou shalt count, and the number of the counting shall be three. Four shalt thou not count, neither count thou two, excepting that thou then proceedest on to three. Five is right out. Once the number three, being the third number, be reached, then you are done.

The inspections satisfy some needed safety concern.  The first inspection is the electrical inspection.  I know the local inspection agency from several other projects and they are familiar with my work, so this one usually goes pretty easily.  I hand him the three line drawing, he looks it over, we catch up on things, he peers into the disconnect switches, shakes the ground wire, looks at the service entrance panels, asks how I like these new inverters, etc.  It usually ends with “nice work, that will be $120.00, certificate is in the mail” and he is off.

The next one is the utility company inspector.  They already have the paper work that was submitted with the application for a net metering account.  Generally, they come out and verify the inverters shut down during a power outage, then proceed to write every scrap of information down that they can find, disconnect switch ratings and model numbers, inverter power factors, breaker ratings, etc.  They stand in the yard and peer up and the panels, point and mumble amongst themselves.  Fortunately, there is no charge for this inspection.

The final, final inspection is with the town building code enforcement officer.  He comes out, looks at it, asks for and receives a copy of the electrical inspection certificate.  Asks if everything is installed the way the manufacture specifies, looks at it some more from a different angle, then knocks it twice with the heal of his hand and says “Yup, that isn’t going anywhere.”

A few days later the certificate of use arrives in the mail and the project is done!  Yay!

So, now for a few exciting things, first of all, if you have never witnessed a power meter turning backwards, here is a little video:

This is a video of the panels in action, generating power:

Finally, this is a monitoring page from my solar company website.  It shows how much power each panel is generating, how much power the system has generated and what the peak power output is on any given day.

Catskillhouse PV system

Or

www.sun-volt.com/pages/pvmonitor.html

That site has pictures of the system and a three line diagram.

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Jan 08 11 comments
Electrical, Environment, Solar Energy

Installing our Photovoltaic system, part IV

Now for the fun part, the frame is all done.  The frame is pressure treated 4×4 post and beam style.  The rafters are pressure treated 2 x 10 x 12 feet.  Over all, it came out pretty nice.  Next year I intend to replace the front deck with a covered porch, also post and beam style, so this should match the look of the house.

Front view of 4.1 KW PV system

Front view of 4.1 KW PV system

Ground mounted 4.1 KW PV system

Ground mounted 4.1 KW PV system

This system is 4.1 KW and should provide almost all of our electric needs once we replace the old refrigerator with an energy star unit.

Enphase M-210 inverter under Sanyo HIP205NHKA5

Enphase M-210 inverter under Sanyo HIP205NHKA5

I used Unirack Sunframe rails to mount the PV modules. The modules are  are Sanyo HIP 205NHK5 Modules and Enphase M-210 microverters.  I like the concept of the Microverter, e.g. each panel has it’s own small inverter.  This allows from some shade tolerance for the lower modules without loosing the entire array.  Also, each panel is matched to it’s inverter at the best efficiency, increasing the overall array output.  Seldom do you get to see the underside of a PV array as they are most often mounted on a roof.

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Dec 21 1 comments
Electrical, Environment, Solar Energy, yard

Installing our Photovoltaic system, part III

Constructing the mounting frame. I had my one “oops” moment in the project already, hopefully there will not be another one. It seems that when I laid out the position of the mounting frame, I was a little too close to the property line. In the end of October, the town that I live in changed its zoning code, making side line set backs 40 feet. The previous code stated it was 10 feet for “unenclosed” uses, e.g. swimming pools, fences, etc. Since the mounting frame is not enclosed, I figured I would be good at 30 feet. No good, the whole thing had to be moved back 10 feet.

Equally unfortunate is the fact that I jumped the gun on the construction and poured the footings before I had the building permit.  So, once again I rented the Kabota backhoe from the Taylor rental place down the road.  I am on a first name basis with the owner, which is nice, sort of.  Anyway, quick work with a chain and I pulled all six of the eight inch footings out of the ground, dug new holes and place the pre-poured footing in a new whole.  I dumped about 6-8 inches of crushed stone in each hole an compacted it.  All in all, I am only out the one day’s rental on the back hoe, which was not too bad.

Timber Frame for 4.1 KW Photovoltaic system

Timber Frame for 4.1 KW Photovoltaic system

On to the construction of the frame.  I decided to use 4 x 4 posts and beams, except for the main support beam, which is 4 x 6 inch.  The entire structure is braced with 4 x 4s at all ninety degree meetings.

Corner bracing

Corner bracing

Of course, the weather has closed in and I am working outside in the snow and wind.  On Saturday, it was 15 degrees out with a 20 MPH wind.  I don’t know what the wind chill was, I can however verify, it was unpleasant working outside.  That being said, progress has been made.

The frame is mostly up, I need to put the final support beam across the top.  Then I need to put in the “rafters” which will be 2 x 8 x 12 treated lumber.  The rafter spacing will be a little odd, since they are space to support the solar panels according to the panel manufactures specifications.

Hand dug conduit trench

Hand dug conduit trench

Also completed (before the ground froze solid) is the trench between the house and the support frame.  We dug this by hand, 42 feet long by 18 inches deep, as the current NEC specifies for PVC conduit.

Everything is frozen solid right now, which actually has it’s advantages.  Come springtime, this will be a soupy mud mess.  Once the ground drys out a little bit, I’ll rake it out and plant some grass seed.

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Nov 21 4 comments
Electrical, Environment, Solar Energy, yard

Installing our Photovoltiac system, Part II

Laying out the support frame.  As mentioned before, the south facing roof on our house is taken up with the solar hot water system.  The only mounting option for the photovoltaic system was to build a sun shade type support frame in the yard.

The first thing that was needed was the size of the array.  For this system, we will be installing 20 Sanyo HIP-205N modules.  These measure 62.2″ x 31.4″.  I would like these to be installed landscape style, four deep by 5 wide.  The total array size is 311″ or 25.9′ X 125.6″ or 10.4′  I am leaving a little room around the edges for a safety factor, so my support frame will be 27 x 12 feet.

I also want  to tilt the array to latitude, which around here is 42 degrees.  There have been studies that show that the tilt angle is not a critical as once thought, however, since I can do it, I might as well.  Therefore, I will install a total of six support posts, making the structure 26 feet x 7 feet.  The front of the structure will be about 6 feet above ground level, the back will be about 12 feet above ground level.

PV system location marked with stakes

PV system location marked with stakes

I staked out the frame and aligned it to true south.  It is only a few degrees off from the property line, so it works out well.  Since we have had a lot of rain this year, I decided to dig a test pit to see where the water table is in relation to the bottom of the footings.  Local code requires 48 inch deep footings, my test pit reached 46 inches deep before I saw some seepage.  I left it over night and the next morning there was about 2 to 3 inches of water in the bottom.  Over all, not too bad, I put some crushed stone in the bottom of each footing before I put the form in.

Test pit to see where the ground water table is

Test pit to see where the ground water table is

It rained most of the day on Saturday, however, I still managed to dig four of the six holes.  On Sunday, I dug the last two.  Then, by this post, I knew that it takes about 2 2/3 80 pound bags of ready mix to fill an 8 by 48 inch sonotube.  I picked up 16 bags of 4000 PSI ready mix.  This time, I borrowed a cement mixer, which made things much easier.  I also used one #4 (1/2 inch) rebar down the middle of each footing, tied to the J bolt on top.  I used 1 gallon of water per 80 pound bag, as the directions on the bag stated.  This made a good stiff mix.

Holes completed, string crosses mark footing locations

Holes completed, string crosses mark footing locations

To make all of the forms the same level, I used a 14′ 2 x 8 and a level.  Going from hole to hole, slowly putting more packed crushed stone in each hole, I think I got pretty close.  Also, the crushed stone will aid with drainage around the bottom of the footing.  Any differences in level can be made up by trimming the posts.

Footing hole, somewhat deeper than 48 inches

Footing hole, somewhat deeper than 48 inches

This was a miserable job.  It was wet and muddy all day long.  One of the hole had a lot of water in it, which needed to be pumped out before I could put the form in.  Our soil is thick clay, which caked on everything, shovels, boots, rocks, etc.  The weather forecast was for sun on Sunday, which turned out to be false.  Still, it is done.

Footings completed and backfilled

Footings completed and backfilled

I was going to use the excavator to dig the trench for the conduit, however, I decided that a ditch witch would be a better idea, less back fill, less mess, etc.  For conduit, I think I will go with two inch.  This system has microverters, which means the feed from the solar array will be 240 VAC.  I could use #12AWG with this and come in at just under 2% voltage drop.  Since I have spools of #8 AWG already on the truck, I will used that cable instead.  That makes the voltage drop 0.6%.  Since there are two 240 VAC branch circuits, plus two neutrals and one ground wire, that makes the total number of conductors 7.  According to the latest version of the NEC (2008), table C.10, 1 1/4 inch schedule 40 PVC conduit is acceptable for this installation.

Once the concrete hardens for a couple of days, we’ll put up the frame.

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Nov 11 1 comments
Electrical, Environment, Solar Energy, yard

Installing our Photovoltaic Solar System, Part I

I have had a pretty good year with the solar business thus far.  Therefore, I decided to roll some of this year’s profits into our own Photovoltaic (PV) system.  This idea has been batted about before, including as a battery back up for the sump pumps, however, a few things have developed since then.

First of all, as technology often does, newer things are available these days that make a solar system in the North East a better proposition.  Secondly, the solar business has done better than I expected.  As a result, I don’t often have much time to work on household projects.  That means that this years “capital improvement” budget has gone unspent for the most part.  Finally, I would like to offset some of the extra income tax from the profits.  What better way than to invest in the technology myself.  The Federal Government offers a 30% income tax incentive and the NY State government offers a 25% tax income incentive up to $5,000.00.  This will cut the overall cost of the installed system by almost 50%.

There are a number of considerations:

  1. How large of a system should be installed.  I decided that I wanted to offset 70-80% of my annual electrical use.  In this climate and environment, that equates to about 4.1 KW DC PV system.  This leaves a little downward room in case I decide to replace the electric stove with a gas unit.
  2. Where can it be installed.  Since the south facing roof has the solar hot water system, the PV system needs to be mounted on a sun shade type structure in the yard.
  3. What type of technology.  I was initially looking at a grid tied with battery back up, however, after I looked into the newest type of inverter, the Enphase microverter, I decided that this was the way to go.  A battery backup can be added at a later date.

The Enphase microverters are really cool.  The way this system works is every solar panel has its own small inverter instead of one large inverter for many panels.   The advantages of this type of system are thus:  In conventional system, shading of one panel can cause the entire solar array to turn off, making it ineffective.  With the microverters, the shaded panel may turn off, but the rest of the unshaded panels still put out full power.  In the Northeast, trees grow everywhere, it is nearly impossible to have a completely shade free site, nor should home owner’s be expected to clear cut their lots to accommodate a PV system.  The Enphase microverters mitigate some of those concerns.

Also, multiple inverters create redundancy.  Any one inverter can fail, leaving the other nineteen still operational.  There is automatic web monitoring for a small annual fee, or the modules can be monitored manually.  I may write a small web based program to monitor and post my energy output here.  The inverters themselves carry a 15 year warranty, whereas most other inverters carry a 5 year warranty.

Finally, there are no DC voltage losses to account for, making the entire system operate much more efficiently.

In anycase, the order has been signed, checks have been written and the excavator has been reserved for this weekend.  The first step is to dig and poor the footings for the sun shade.

More to follow.

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