Renewable energy Net Metering billing explained

I installed the first phase of my solar power system back in the summer of 2009 with the help of many friends and neighbors.  Once the system was commissioned and approved by my utility, I signed a Net Metering Agreement with them.  This contractual agreement stipulates that they give me full retail credit for every kilowatt hour of energy that I export from my property back into the grid.  Originally, I had a traditional old-style analog meter and this meter would simply turn backwards on a sunny day before they came out and installed a second meter as part of the Agreement.  From this point forward my bill indicates readings from both meters.  One meter indicates how much energy I have imported from the grid, and the other indicates how much energy I exported.  I am billed (or credited) for the NET difference.

My electric meters

In the image above, the top meter shows that I have imported 22476 kWh and exported 11017 kWh since these meters were installed in April 2011.  Essentially I have offset 50% of my energy over six years using solar power.  Since the system has grown over time that percentage is currently higher.  For instance, over the last 12 months I exported 3383 kWh, imported 5222 kWh with a net usage of only 1983 kWh

In the summer months I export more than I import and thanks to the Net Metering Agreement, the utility gives me a full retail credit for every kilowatt hour exported and this credit is carried forward.  They do not pay me directly but simply apply this credit to subsequent bills until such time as I use it up.  They do not carry a credit forward if it has run over 12 months.  I have had a very good year this year and have not paid my utility for electricity since May (it is now mid-October) and I am still carrying a credit that will apply to my next electric bill.  Here is the section of my bill indicating the most recent meter readings:

Section of my electric bill showing imported and exported energy.

Not long after commissioning my system, I installed a TED 5000 real-time energy monitor in my circuit breaker box.  This feeds information to a web page that I can view on my local network.  This helpful tool allows me to view energy consumption in great detail in various charts showing energy consumption by the second/hour/day/month.  Below is a screenshot showing monthly energy flow for the last couple of years:

Chart updated in July 2016

 Blue indicates energy imported,  yellow  indicates solar energy produced and  green  indicates the net energy per month.  I had a net energy surplus for 3 months each summer.


In a larger context, I am considered a micro generator that contributes power to the grid.  By doing this, I am reducing the load on the local grid which actually does the utility a favor.  However, the utilities do not see it this way due to the lost revenue and many utilities are beginning to fight back to prevent them having to give credit or payouts to people that provide renewable energy into the grid.  This is shortsighted thinking and they are going to have to adjust their business model as more renewable energy systems are brought online.

Energy efficient motion sensing night lights

I am revisiting the topic of night lights.  Last month I wrote about "Low Cost to Operate Night Lights" and discussed electroluminescent and LED nightlights that provide a sufficient glow for navigating a dark home at night.  These lights stay on 24/7 and thus they are on in the daytime when they are not really needed, however since they only cost around $.02-$.10 per year to operate this is of little concern.

Motion sensing night light

Recently I decided to try out some motion sensing LED night lights that only illuminate when motion is detected in a darkened room.  These well-designed units are available in packs of two for about $20, and come in cool white and warm white options.  I placed one in my front hallway and another in the bathroom and have found that I now no longer need to turn on the lights when going to the bathroom at night or when coming into the house after dark since they provide sufficient illumination to see.  This is significantly more light than the always-on LED lights I reviewed recently.  It is quite pleasant to have a light come on automatically just when and where you need it.  They have an impressive range and turn on instantly when they detect someone moving around at night and remain on for 60 seconds.  If you stand or sit perfectly still, they will go off which can be sometimes disconcerting in the bathroom, but the moment you move again they come back on.  For this reason I wish there was a switch to enable them to stay on longer.

Motion sensing night light only activates in the dark

As an engineer I naturally needed to quantify how much energy these lights use compared to the LED lights I wrote about recently.   I found that they consume about 3 Watts in both the off and on state - about half the power of an old-style night light lamp.  I was actually a little surprised to find that the unit uses slightly less power when the light comes on!   Clearly the motion sensor is using power all the time to  detect motion and ambient light.  This means that their cost to operate if you are paying $.10 per kilowatt hour for electricity (which is the US national average) is around $.21 per month or $2.60 per year.  While this is more than the $.10/year cost to operate an always-on LED nightlight I find the trade-off quite amenable.

The sensor is a Passive Infrared Sensor (PIR) that works by detecting infrared light emitted by warm bodies.   The lens in the dome of these sensors focuses IR light onto a device that triggers when it sees warm objects passing across its field-of-view.  There is also a photocell that detects ambient light level and disables the light when the ambient light is above a certain threshold.

I am so pleased with these lights that I plan to order a couple more.  While they do use more energy than other types, I have enough surplus power from my solar array that I can spare a few Watts.  I have not paid for grid power since May (just payed my Sept-Oct bill and still have a credit on my account thanks to net metering).

Charging up my solar heating system

South end of my workshop showing 4 solar collectors

It is mid October and we have had our first few frosts here in Maine and they had a few inches of snow in western Maine yesterday.  This means that it is time for me to fill the solar collectors on my workshop heating system with antifreeze.  The heating season lasts until mid-May here and in the winter temperatures rarely get above freezing for up to three months.  My workshop building is super insulated and I heat it with a combination of solar, propane and a wood stove.  I use a cord of wood that I cut and split myself from my backwoods to heat the downstairs area, keeping it around 60°F and higher if I am actively working in the space.  I use the solar/propane primarily to heat my second-floor office where I am more sedentary and set the temperature around 70°F or so during my working hours.

Pumping a bucket full of antifreeze into the collectors

To fill the collectors, it takes around 6 gallons of 50% Dow Frost antifreeze.  I use a small electric pump and hoses to pump this fluid into the system and pressurize it to 10 psi.  It takes a while to eliminate all the air bubbles from the system so I leave the pump circulating for a while to push the bubbles out of the plumbing and collectors.

DTC-D Solar Differential Temperature Controller

Once the system is filled, I connect the 3 small solar panels on the roof to the Differential Temperature Controller that I designed and manufacture (shown above).  This device monitors the temperature of the collectors and the storage tank and only activates DC circulation pumps when the collector is hotter than the storage tank by at least 10°F.  Powering the circulation pumps directly from solar panels guarantees an efficient and reliable heating system.

You can see live performance charts and gauges of my heating system on this page of my website.  On a good sunny day in the winter the system can raise the 80 gallon storage tank temperature by over 40°F.  The stored heat is then fed to baseboard radiators at night as needed.  If the stored water temperature drops below 140°F a Bosch Aquastar boiler automatically makes up the difference to ensure that heating water is always delivered to the radiators at 140°F.

Unsustainable tech product packaging

Linx evaluation kit - case not to scale

For the last 40 years or so I have been designing and developing electronic products.  Many of these products incorporate short range radio controls, and this has become a specialty of mine.  For the last 20 years or so I have been working with a company called Linx Technologies that make a broad line of miniature radio chips and antennas that are ideal for small products.  When they introduce a new product I sometimes order an evaluation kit from them that typically costs around $100.  These kits include battery-powered demonstration circuits that help to familiarize you with how they work.  

Linx have just released an exciting new radio product that I plan to use in a project I am currently developing so I ordered the relevant evaluation kit (see their promotional image above).  In the past, these kits were shipped in small custom fitted cardboard containers and it was quite simple to recycle the cardboard materials.  Not so with this newest kit that came in an aluminum case that weighs almost 3 pounds and measures 14" x 10" x 4".  I was stunned when the package arrived because it was so huge and heavy.  The distributor (Digi-Key Corp.) packed it in sustainably sourced paper packing material that can be recycled, but I have no idea what I am supposed to do with this large metal case.  I do not need to clutter my home office with this albatross, and will simply store the components on a shelf.  Here are is a picture of the relatively tiny (and not very fragile) parts inside the case:

Kit with all parts visible

I find the idea of shipping small items weighing only a few ounces in a 3 pound case to be completely offensive to my sensibilities as someone committed to living sustainably.  From my perspective this is a 1950s style Mad Men style promotional concept that has no place in today's world and it made me angry.  I also have to question the 1 pound stack of documentation that came in the kit.  While it is convenient to have paper manuals, technology companies do not commonly send any paper documentation with their samples since everything an engineer needs to know about their products is available from their website.  15+ years ago I used to have bookshelves filled with thick technical manuals, but they have all disappeared in favor of PDF documents readily available on corporate websites.

My small rural town recently switched to a Pay As You Throw (PAYT) program which requires our trash to be placed in specially purchased orange trash bags that cost $1 for a small bag and $2 for a large bag.  The purpose of this program is to incentivize increased recycling in our town and I am hoping it will have the desired effect.  Currently the town recycles around 20% of its waste stream, while I am averaging 60%.  The impact of the new program on me is that I resent companies that send me products packaged in bulky non-recyclable materials.  I have conveyed my displeasure to the sales person I work with, and he says he will talk to the marketing department at his company about my concern.

There are so many companies that are embracing social responsibility on so many levels that it makes me sad to see a good company that ignores the realities of a planet with finite resources.

After seeing this blog post, the Linx salesman that I work with offered to pay for return shipping of the offending metal case via FedEx.  I appreciate his thoughtful response to my displeasure.

A friend saw my blog and has asked if he can have the case.  Giving it to him has a lower carbon footprint than shipping it back across the country.  Everybody wins!

Sustainably sourced dining room chairs

My wife and I have separated after 20 good years and she has moved back to California where we first met.  It is an amicable separation but nonetheless she ended up taking a lot of furniture and other essentials with her.  This left me without a set of dining chairs.  Ideally I wanted chairs that were sustainably sourced in some way.  My original thought was to approach my friend and neighbor, John who is a skilled furniture maker because he had recently made a really stunning set of craftsman style chairs for his home.  But he explained that it would take up to a week per chair to make them even if I was helping and I realized I had neither the time or the money to invest.

My next step was to go to a local furniture store that represents Amish furniture makers.  They had a variety of samples that I found quite suitable for my needs at prices ranging from $230-$265 per chair and this was the upper limit for my budget.  The problem was that it would take 6 to 8 weeks to have the chairs made.  At this point it occurred to me that I really do not need heirloom quality furniture since I have no children or heirs who may wish to inherit furniture from me.  Also I did not want to wait that long because I had decided to convert the guest room in my house to a B&B using airbnb and wanted to get that set up pretty quickly.  Click here to see my listing, I have already had a few guests and I am getting reservations for the fall color season here in Maine which peaks in mid October. (We refer to the out-of-state visitors who come for the fall as "leaf peepers"). 

So finally I resorted to searching for chairs on the web and found a nice set of chairs from Sears.com on sale for under $50 each.  While I was not particularly comfortable with the idea of chairs that are made in Malasia, I did learn that they were made from "sustainable rubber wood".  In doing my research I learned that rubber wood has come into usage in the last few decades as a secondary use for trees from rubber plantations.  When these trees reach the age of around 30 years, their production diminishes and they  are harvested for their wood and the plantation is replanted.  The wood itself is prone to infestations from beetles, but when treated properly and dried correctly it can look somewhat like mahogany.  It is an attractive hardwood that takes stain and finish very nicely.

The chairs arrived at the local Sears store in a few days partially assembled in flat boxes.  Assembly was surprisingly simple and easy and I was impressed with the quality of the finish and the engineering of the joinery that makes for a very sturdy chair.

Chair parts

First chair assembled

The chairs did not take long to assemble, and look good with my family heirloom Jacobean reproduction oak table from England.

Whenever I need to purchase anything, I recognize that I am voting with my dollars for - or against - a sustainable future for humanity.  I take every decision quite seriously, particularly when dealing with large items.  But this also scales down to purchasing food at the local grocery store, natural food stores, and farmers market.  I make every effort to support local agriculture or acquire foods that are not shipped in from another country.

Low cost to operate night lights

Here in rural Maine there are no streetlights or reflected city light at night so it gets DARK at night.  This means that when the lights are out inside the house it can be difficult to navigate to the bathroom or kitchen.  So for this reason I have liberally sprinkled nightlights throughout the house to make it easy to get around without having to turn on  lights.  

7 W night light

The classic old-style standard 7 W light bulb style nightlight has been obsolete for several years and I personally have never used them but I did the math and calculated that if you are paying $.10 per kilowatt hour (which is about average) for electricity, each one of those old light lights would cost over six dollars a year to operate which is more than many of them cost to purchase new off-the-shelf!  if you happen to have one of these dinosaurs in your home, I encourage you to discard it immediately and upgrade to the newer technologies.

In the past I have purchased three packs of electroluminescent nightlights for around $10-$12 and they tend to last several years before they eventually grow dim and become relatively useless.  I tested one of these lights and found that it draws .033 W for an estimated cost of about 2.5 cents/year.  A few days ago I was in the hardware store and saw a two pack of blue LED nightlights selling for under nine dollars and thought I would try them out.  LEDs draw a little more power at .125 W for an operating cost of around $.10/year.  LEDs are typically rated to last 30,000 to 50,000 hours so I expect these to last 3 to 5 years.

Here are some comparison images of LED (top) and electroluminescent (bottom)  with ambient lighting and lights out:

LED vs electroluminescent night light in ambient light

LED vs electroluminescent night light in the dark

The LED is significantly brighter and cast a visible pool of light in a dark hallway, while electroluminescent ones are just enough to see by, similar to moonlight coming through a window.

There are other types of night lights that contain light sensors and motion sensors so they turn off when they are not needed.  I suspect that those that use a motion sensor consume a fair amount of power even when they are off just to maintain the motion sensor.  (they do, see this blog post).  I leave mine on all the time since their cost to operate is so trivial.

Another small repair

This beautiful polished metal torchiere lamp was damaged a few years ago at the point where two of the sections of the main column screwed together.  It has been limping along for a while and I decided to repair it to use in my spare room which I will be renting out as an airbnb room soon.  Shown above is the repaired lamp that has been fully retrofitted with LED lamps.

The repair was relatively simple for me as a woodworker.  I cut a strip of ash and then milled out slots to create a "splint" for the bottom half of the lamp column.  Here is the before picture:

 

And a close-up of the wood channel that I made:

 Which I glued on around the column:

Works like a charm!

From a sustainability standpoint this is another large, heavy item that did not make it to the landfill.  Plus it saved me the expense of purchasing a new lamp!

 

A thinner wallet can be a good thing!

A few years ago I decided that my wallet had become too thick.  It contained the usual assortment of cards including driver's license, library card, debit and credit cards and also half a dozen rewards cards.  So I decided to do something about it.  I scanned in the face of all of my rewards cards, and then scanned the bar codes on the back and then tiled them all together in Photoshop:

I scaled the bar codes as large as practical and have never had a problem with them scanning at the cashier.  After I printed out the card, I covered both surfaces with 2 inch wide clear packing tape to protect it.

Now when a cashier asks me for my rewards card, I offer them the card and isolate the bar code they want to scan between my fingers so the scanner does not get confused by reading the wrong bar code.  A number of cashiers have complimented me on my clever idea so I thought I would share it with my readers.

Chiropractors are aware that sitting on a thick wallet can contribute to a whole host of issues ranging from scoliosis to neck pain, and I certainly feel more comfortable now that it is nearly 1/4 inch thinner.

* A reader just commented that there is "an app for that" called Stocard.  I personally don't use a smart phone, but this seems very useful.  Not sure where most folks carry their phones, but if it's in their back pocket, they will still have back health issues.

It's Brush Hog Day!

My 2.5 acre rural lot here in Maine is mostly wooded and the front half acre or so is divided between lawn areas and open field where I let the weeds grow.  I maintain the lawn with my solar powered lawnmower.  At this time of year the Goldenrod and other tall weeds are over 4 feet tall so I hire a neighbor with a brush hogger to cut everything back.  This also helps to fight back the tide of saplings encroaching from the woods.  If left uncut the entire property would be overgrown with tall trees within 10 or 15 years.  My neighbors on each side both have much larger lots of 10 acres or so each with open fields.  One neighbor brings in a crew to hay and bale his field while the other just cuts it back as I do.

Opening up the field gives us better access to the burn pile.  This is a pile of tree branches and saplings that I clear throughout the year.  Some neighbors wait until the pile is many times the size of ours and have a big bonfire when the snow is on the ground.  I like to keep my burns smaller and more manageable so I light them two or three times a year in the spring and fall.  

Last year I lit off the burn pile before it was brush hogged, and even though I mow a circle around the burn pile, it made for close quarters while maintaining the fire.  I think I will wait until the weather is cooler before burning this pile, it is way too hot and humid.

I enjoy being outside and actively maintaining my property throughout the year, it is good exercise and keeps me in touch with seasonal changes on the land.

Bumper crop of fruit

The previous owners of my property had planted 4 high bush blueberry bushes, and numerous fruit trees about 20 years ago.  I have carefully pruned and maintained the blueberry bushes and pick as many as 5 or 6 gallons of blueberries a year, this year I have a bumper crop, and the branches are bowed down with berries.  It is hard to keep up and I have invited the neighbors to come and help themselves.

 

These are large, sweet blueberries and it is hard to resist eating them while picking!  I also had to deploy a small electric fence around them to keep the wild turkeys and deer from devouring them.  There is a flock of a dozen or so chicks with three or four hens that come around almost daily scavenging what they can.

The apple tree had been producing a moderate number of small sweet cooking apples over the last few years, but this year there are literally so many apples on it that the weight has bowed the branches down to the ground and it has collapsed over my firewood pile.

On closer inspection I realized that this largest main branch has actually broken off at the trunk and I will have to cut it off.  I hope it survives long enough to yield fully ripened apples.

Talk about going out with a bang!  Perhaps I should have been more proactive the pruning for this tree but it is impossible to anticipate a bumper crop of apples like this.

I really enjoy the seasonal cycles here in Maine, the growing season so very visible and tangible because is so short here.  Any day now they will start to cut the 50 acre hayfield across the road from our house and that is always an interesting process to watch.