Saturday, October 31, 2015

Shopping at my local Farmers Market

Bath Farmer's Market on the riverfront
Now that I am renting out my guest room as a Bed and Breakfast (via airbnb), I have decided to feature local foods for breakfast.  So I go to the local farmers market in Bath every Saturday morning which is on the riverfront about 5 miles from my home.  It is late October here in Maine and today is the last day that it will be held outdoors and it was quite brisk with temperatures in the low 40s.  For the winter the market moves into a large boat shed further up the riverfront.

I offer my B&B guests a breakfast that includes eggs from free range chickens, locally made turkey or pork breakfast sausage and/or locally made bread with my homemade Crabapple jam or jelly.  I also offer them dinner if they wish and I prepare anything from burgers made from local grass fed beef to salmon cakes served with locally grown vegetables.  I often find home made pies or muffins to offer for dessert.  Blueberry pie is a local favorite.
Goranson Farm stand
It is always a pleasant experience to review all of the offerings at the market and bump into friends and neighbors who are also shopping.  Some of the local farmers are better known to me than others.  I have visited the Goranson family farm several times and have watched them processing maple syrup in the spring.  They are one of the biggest organic farmers in the region with a large variety of produce.  I am always pleased to be able to support my local farmers and my guests compliment me on the food I prepare for them.

Community Supported Agriculture is a growing and thriving industry here in Maine.  There is a Farm to School program that has become quite successful at bringing fresh foods into the schools.  It is encouraging to see this focus on natural and organic foods and the public response to it.  While natural food can be more expensive, I firmly believe in voting with my dollar for a more sustainable future for our planet while also the supporting local economy.

Sunday, October 25, 2015

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.

Thursday, October 22, 2015

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).

Saturday, October 17, 2015

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.