Installing a 245 W solar panel on my house

The solar array I have installed on my barn workshop currently consists of 31 solar panels all using Enphase micro-inverters.  The original batch of panels were only 175 W and cost me over $4/Watt in 2009, solar panel prices are now down to around $.50/watt.  I have been eyeing a spot on the south facing wall of my house for years and when my friend Paul Kando generously offered to sell me a 245 W Schuco solar panel that he did not need for $100, I jumped at the chance.  Paul has been involved in renewable energy since the 1970s and is very active raising consciousness about renewable energy here in Maine.

I purchased an Enphase M250 microinverter (pictured in the image above mounted to the back of the solar panel) and then bolted some angle brackets to the panel to create a wall mounting system.  I gave a great deal of thought on how to install this panel safely and called in my friends and neighbor to help install it.  Thanks to my careful planning the installation took less than an hour and went like clockwork.

We got 2 very long ladders up and then mounted 4 brackets I had made to the wall.  I made a wooden jig that to ensure they were spaced correctly.  Then we hauled the panel up by dropping a rope from the attic window and secured the top of the panel with two bolts.  We were able to push the bottom edge of the panel out from the second floor bedroom window with a long board that I notched at the end for the purpose.  This made it easier for the two guys on the ladder to bolt on the struts that hold the panel out at an angle of around 39° from the wall.  I chose this angle to optimize winter performance (we are at 44° latitude here in Maine).

Before the installation, I had pulled some 14/3 Romex from a junction box in the attic down to the breaker box in the basement.  I added a 15 amp 240 V dual breaker for the solar panel.  The following morning at around 10:30 I clipped my Amp meter onto one of the wires and got a reading of .688 A on one of the lines - so that's 144 W.  

According to calculations using the online PVWatts calculator the annual energy value for this panel will be $42 a year.  So this panel will pay for itself in less than eight years by reducing my electric bill by around $2 to $5 a month.  Another way of looking at it is that each month this panel will provide enough energy to drive my Chevy Volt electric vehicle roughly 30-70 miles depending on the time of year.
 
My costs were relatively minimal:
$100 Schuco MPE 245 solar panel
$144 Enphase M250 micro inverter
$29  Enphase Engage cable
$20  Enphase M215 branch Terminator 
$20  30ft 14/3 Romex wire (run to the breaker box)
$313 TOTAL

The other advantage of installing this panel above my bedroom windows is that it will provide shade during the summer.  I do use a small window air conditioner occasionally in July and August and this should reduce the need to use that a little.

Many thanks to my neighbors and friends who are all energy mavens:
John Rogers, experienced home builder and fine furniture maker.
Topher Belknap, home energy auditor and building efficiency expert.
Al Heath, experienced home builder and energy auditor.
We all had a lot of fun installing this panel and I could not have done this without their help.

Update a week later

I did want some way to monitor power output and decided to install a small energy meter above the circuit breaker box in the basement.  This meter only costs $25 (available from MPJA) and I mounted it in a plastic box for another $10 or so.

It shows instantaneous Watts on the lower left corner and cumulative Watt hours on the lower right corner.  I plan to log the kilowatt hours weekly so that I can track performance of this single panel.  If anything should go wrong, I would certainly notice a lack of performance by the end of the week.  Here's a photo of it mounted above my circuit breaker box

clearing a tree that was shading my solar collectors and satellite dish

When a tree becomes inconvenient, it must go!  Case in point is a pine tree near my house that had been partly shading my solar collectors for the hot water for my home in the afternoon.  I was willing to tolerate that, but eventually it grew high enough to block my Dish satellite so that I was losing HD signals.  Two strikes and it was out!

Offending Pine tree on the left

You can see the offending tree on the left.  It is concealing the satellite dish to the left of the dormer window on the left side of the house, and the solar collectors are below the second floor windows towards the right.

Trunks down and partly bucked

So I called my neighbor John who is always happy to help me cut down a tree and he came over with his pickup, chainsaw, length of chain and steel rope to tension the tree and we got to work.  It took some careful strategy to tie a cable from the tree to John's pickup so we could haul it in the right direction as it came down.  There were two large main branches, one went to the left, and the other to the right and down slope.  They both landed pretty much where we wanted them.

We hauled off all the branches to my burn pile and lit that off while we were cutting up the trunk.

Burn pile before

Pine needles burn very quickly so the fire did not need a lot of tending and maintenance, although it was somewhat smoky.  There's nothing like the smell of wood smoke in the fall.

Burn pile almost done.

We cut the trunk into firewood lengths and I have stacked it in the backyard to season for a few years before I split it.  Pine wood has so much pitch that it takes a long time to dry out.  It's not a good idea to burn unseasoned pine in the wood stove because it creates a lot of creosote buildup in the chimney.  That creosote can create a chimney fire and burn down your house.  I get my chimneys cleaned every year or two just to be safe.

Tree stump and stacked firewood

Now the tree is down, my satellite dish has a clear line of sight to the HD satellite, and I'm getting better performance from my solar collectors.  I guess you could say I am back in hot water!

A clear line of sight for my solar and satellite

While I have contributed a substantial amount of carbon to the atmosphere by burning the tree, I see it as just shortening the carbon cycle.  The tree would eventually have died and rotted, releasing carbon back into the atmosphere.   I am sure the equation does not pencil out optimally, but by gaining more free solar energy, it probably nets out.

Making crabapple butter and jelly

I have a large crabapple tree in my yard that can yield up to 70 pounds of ripe crab apples.  I try to use as much of the fruit as I can to make crabapple butter and jelly.  It is tasty stuff, and I often sell jars of it to my airbnb guests.

I begin by laying out a large tarp under the tree and then shake the branches vigorously using a long extendable pole with a hook on the end:

Then comes the process of sorting the good fruit from damaged or bug infested apples, here is my friend Alison helping me with that step:

This results in a bucket filled with good clean, ripe crabapples weighing up to 20 pounds:

In the kitchen I weigh out around 10 pounds of crabapples and cut the ends off each one and boil them in a large pot until they are mushy.  If I am making crabapple butter, the mush is strained through a press to eliminate seeds and skins etc.  Or, if I am making jelly, I dump it into a cheesecloth lined strainer to drain the juices out overnight:

The resulting juice or clarified mash is then boiled in a pot with an equal amount of sugar and additional spices like cinnamon, thyme, allspice etc.  I use raw sugar rather than refined white sugar:

Since crabapples have a fair amount of pectin in them, there is no need to add it in order to get the jelly or jam to set up.

The final step is canning in which the hot juice is poured into sterilized glass jars and set aside to cool:

10 pounds of crab apples will yield a dozen or so jars of butter, or eight or nine jars of jelly:

The whole process can take over six hours from shaking the tree to finished jam, but it's worth it!  I am often complimented on how tasty my jams and jellies are.

I try to make best use of all the natural resources available on my property.  My raised vegetable beds have yielded a good crop of sugar snap peas, cherry tomatoes, basil, rhubarb, and some other herbs and spices.  I also use responsible forestry management techniques to harvest trees from the woods behind my house for firewood to heat my workshop. (here is my blog post about that). 
 

Roof mounted solar panels cool inside the building

I was looking up at my solar panels on a very hot sunny day recently.  I noticed that they were shading the roof and wondered if they were having a cooling effect and thus reducing the air-conditioning load in my office below.  So I set up 4 temperature sensors connected to my data logger to look at a days worth of data on a clear sunny day when the ambient temperatures peaked at around 100°F in the shade.

Click image to enlarge

As you can see, the shaded roof temperature averaged about 10°F cooler than the exposed roof.  I expected the solar panel surface temperature to be significantly hotter, but it was only about 10°F above ambient.  I'm not certain that my methodology was perfect.  All I did was tape a sensor onto the back of the solar panel and secure the others to the roof with duct tape.  The ambient temperature sensor was in the shade away from the roof.

The take away here is that solar panels do have a cooling effect when covering an asphalt roof.  This is clearly an advantage when the rooms below that roof require air conditioning in the summer.

Another way to reduce air conditioning costs is to install a solar powered ventilation fan in the attic.

I installed a SunRise Solar Attic Fan many years ago and it reduced my attic temperature by up to 60°F.  These clever designs use a 10 W solar panel directly connected to a fan.  You can add a thermostat to ensure that it is not running when the attic is cool.

So one can definitely say that solar panels are cool!

Treating bug itch with technology

In my previous post, I reviewed small plug-in bug zappers that work very well at eliminating those few mosquitoes that get into my home.  Nonetheless, I get bitten fairly often while outside enjoying the beautiful Maine summers.  Years ago I read about a simple no-cost treatment for the itch and swelling of bug bites - you simply run the affected area under very hot water for as long as you can stand it.  Apparently this changes the composition of the histamine chemistry in your body.  I have used this technique for years and it is extremely effective at removing the itch and swelling almost immediately.  The only problem is when I get bit on a part of my body that doesn't lend itself to being placed under a faucet.

The solution is to use a device that can concentrate localized heat right on the bite.  It turns out there are a number of products on the market that do just that.  The Therapik Mosquito Bite Reliever is a small, affordable battery-powered device that works extremely well in my experience.  (Click here to purchase on Amazon - As an Amazon Associate I earn from qualifying purchases.)

Therapik Mosquito Bite Reliever

This cool (hot!) device looks like a weapon from Star Trek the TV series.  One simply holds the red circle against the bite while holding down the button.  

A bright light comes on inside that quickly heats up the affected area.  The suggested hold time is around 20 to 30 seconds or to the point where the pain becomes unpleasant.  Some people make the mistake of turning off/removing the device as soon as they feel some heat which is typically within five seconds or so.  But it is important to maintain a connection long enough that the affected area is thoroughly heated up to the point of discomfort.

applying heat for 20 seconds or so

The Therapik operates from a single 9 V battery that seems to last a long time.

I read a German clinical study of a similar (but more expensive) product in which they concluded: "Locally administered, concentrated heat, which was recognized by the patients as a very short and targeted induction of almost painful high temperature on the skin, led to a fast improvement of ... swelling, pruritus (itching), and pain ... symptoms.  Compared with alternatives of pruritus and pain treatment after insect bites/stings, (it) seems to be the fastest treatment option already available."

I could not agree more.  So yes, this product (and ones like it) are the real deal.

Eliminating mosquitozzzzz in the home

Every now and then a male mosquito will find its way through my window screens or front door and into my home.  Of course that sound is extremely annoying, but it's the females that don't make so much sound that I also worry about because of the diseases they can carry.  Over the years, I have experimented with a variety of solutions and currently use a large 40 Watt zapper (Flow Tron BK-15D) that I run on a timer at night out in the backyard.  While it is very effective at reducing the outdoor population, some do get inside.  I had been using a smaller AC powered one in my front hallway that zaps them before they can get too far.  The only drawback to that relatively large zapper was the sound it makes inside the home. While the occasional ZAP was gratifying, it could often be annoying.  Unfortunately, that unit failed recently so I started researching other options.

What I found is that there are a number of simple, small, ultra-low power devices that plug into an electric outlet and consume a minuscule amount of power while solving the problem handily.  This model is no longer available, but similar ones are available.  (Click here to purchase on Amazon - As an Amazon Associate I earn from qualifying purchases.)

Zapper with 100% recyclable cardboard packaging

I was particularly impressed that the product is packaged in a simple recyclable cardboard box.  The only instructions are on the back and were clearly translated from another language with such amusing lines as: "LED lights glow to attract mosquitoes: stimulate airs, emit violet light to attract mosquitoes into the hood."

When plugged in, 2 small ultraviolet LEDs come on to attract bugs to the electrode grid inside where they die a quick and quiet death.  No loud zapping!  This subtle purple light can also serve as a modest nightlight.

works as a nightlight

The Manufacturer suggests you to take it apart (three screws on the back) and clean up the electrodes when they catch a lot of bugs.  Here's what it looks like inside.

Remove three screws to open it up for cleaning.

I ran some electrical tests on the device to see how much power it consumes and found that it draws 3.2 mA (3.8 W).  This means that it will only add about 27 cents to your monthly bill (assuming 10 cents/kWh).  So for the energy conscious, this is not a big concern.  

I also tested it by inserting a screwdriver (holding the insulated handle carefully) to short out the electric grid and it did produce some substantial sparks.  For this reason it would be wise to keep this away from young children.

To give the device a rigorous test, I plugged it into an outside outlet for a couple of nights and it caught quite a number of bugs.

bug catch after two nights outdoors - click image to enlarge

I have deployed these clever devices in my kitchen, living room, and bedroom and I am confident they will catch the occasional mosquito that gets into my home.  I also find them to serve as a pleasant night light. 

As someone who designs electronic products for living, I would be very proud of this design.

There are quite a variety of similar devices on the market, including a very clever version that screws into a lamp socket and incorporates an LED light. (Click here to purchase on Amazon - As an Amazon Associate I earn from qualifying purchases.)

Mosquito Light Bulb Bug Zapper

I did not have a suitable location in my home for this type of lamp, but would seriously consider it for laundry/utility rooms and basements etc.  Apparently the bug zapper remains on when the LED light is off consuming around 3 W, while the LED lamp uses around 10 W.  These devices seem to get very good reviews on Amazon and there are many very good deals on them if you look carefully.

I don't think these devices should be confused with heavy-duty bug zappers.  They are really designed for the occasional incursion so should not be used in the same way as a larger zapper.  I would definitely not recommend them for outdoor spaces other than small screened in porches.

Once you do get bit, there is an amazing techno fix that cures the itch and pain almost immediately.  See my next blog post for a review of The Therapik Mosquito Bite Reliever

Calculating energy cost of lamps and appliances

Conserving energy benefits the planet, while also conserving costs.  With this in mind it is helpful to be able to calculate how much money one saves by replacing an inefficient appliance or lamp with an energy efficient one.  For this example we will look at replacing an old 100 Watt incandescent lamp (which are being phased out around the world) with an equivalent 13Watt 800 Lumen CFL (Compact Florescent Lamp) and another equivalent brightness 10W LED lamp.

First, let's review the three salient electrical properties we are looking at here.  Volts which for the sake of this discussion is the available Voltage at a standard electrical outlet in the US which is 120 V.  Amps is the amount of current, and Watts is the product of Volts and Amps (W = V x A).

13W 800 Lumen CFL

In order to calculate cost, we first need to figure out how much power we will be billed for on a monthly basis.  Electrical power is billed by the kilowatt hour (kWh) which means 1000 W per hour.  Or another way of looking at this would be the equivalent of a 1000 W heater turned on for one hour.  The average cost per kWh in the US is approximately $.10, however that rate varies significantly from state to state and region to region.  Here in Maine we are paying approximately $.15/kWh.  It is also worth noting that the percentage of renewable energy sourced electricity varies significantly.  In New England we have the RGGI (Regional Green house Gas Initiative) that mandates a minimum amount of renewably sourced electrical power.  In Maine about 30% or our power is renewable sourced much of which comes from Canadian hydro, with the remainder sourced from biomass, wind, and solar in-state.

So let's start with an old-fashioned 100 W light bulb and assume that it is on in your living room for 6 hours a day.  To calculate how many Watt hours (Wh) are used per day we simply multiply:

100 Watts X 6 hours = 600 Wh

Which can be expressed as .6 kWh
Since we are billed by the month, we can multiply this by 30 to determine how many kilowatt hours per month we will be billed for:

.6kWh X 30days = 18kWh/month

To determine our monthly cost for this lightbulb, we simply multiply by the electric rate, so let's assume the US average of $.10:

18kWh X $.10 = $1.80/month

That doesn't look too bad does it?  But if you run the math for an energy efficient compact fluorescent lamp you get the following:

13W X 6hrs = 78Wh

.078kWh X 30 days = 2.34kWh/month

2.34kWh X $.10 = $.23/month

So by replacing that old style lamp with a compact fluorescent you would be saving $1.57 every month while also reducing fossil fuel emissions required to generate power for this electricity.  If you do the math for a 10 W LED lamp it comes out at $.18 per month with a net savings of $1.62 every month.  These lamps are so inexpensive now that you will recoup the investment within 5 months and since LED lamps last significantly longer than incandescent lamps it is a gift that keeps giving both to your wallet and to the planet.  Also, LED lamps contain no mercury.

9.99W 800 Lumen LED lamp

If like me, you have been using CFLs for years and are now in the process of upgrading to slightly more efficient LED lamps, please be sure to recycle the CFLs responsibly since they contain an average of about 4mg of mercury.  Lowe's stores have bins where you can return CFL's and also rechargeable batteries and plastic bags right next to their returns counter.

Recycling bins at Lowe's - next ro returns counter

So next time you go shopping for any electrical device from a lightbulb to an appliance.  You should start by looking at the label on the appliance you are replacing to see how much power it uses and do the math to figure out what it is costing you now and how much energy the new one will save.  If the nameplate on your appliance only shows the power in Amps, then just multiply it by 120 V to get Watts.  

Newer appliances are often more efficient.  For instance, it is generally assumed that if your refrigerator was made before 2000 that newer ones will be significantly more efficient.  So you will not only be saving money, you will also be doing the planet a favor by reducing CO2 emissions from the fossil fuels used to generate electricity.

A real-time energy display for my solar power system

Ever since one of my electronic parts suppliers (MPJA) got in a line of cool blue digital meters, I have been applying them everywhere.  See my recent blog posts describing the gauge I added to my solar charged electric lawnmower, and temperature gauges that I added to my solar hot water heating system.

When I give a tour of my renewable energy systems, I point to the circuit breaker panel where the 240 V AC comes in from the roof mounted solar array and feeds out to the main breaker panel.  

Breaker panel, new meter (circled) and Envoy

Next to it (the white oval device) is the Envoy web Gateway for the Enphase microinverters on the roof.  

Envoy Enlighten live web portal

The Envoy allows real-time monitoring of every solar panel and creates a live web portal (that I embedded in my web site) showing performance of each panel and how many watts it is producing right now and over time.  The problem is that the Envoy only shows total wattage in a small hard to read small display, along with a few other statistics like the number of microinverters reporting and the total megawatt hours produced. 

What I needed was something that can be seen easily that shows the amount of power my array is producing in real time.  So I installed a multifunction meter (circled in the image above) that displays  Volts, Amps Watts, and kWH on a clean brightly lit display:

Now it is easy for me to tell people as I show them my system that it is currently generating 4497 Watts, and if a cloud goes by one can see the numbers changing dynamically.  The number at bottom right shows kWh since the meter was last reset (= 1.6MWh).  My system generally produces between 4 and 5 MWh per year.  As a geek, I have to admit that I am a sucker for a sexy blue techno glow display!

A new meter for my solar charged electric lawnmower conversion

Okay, so I am a geek!  11 years ago, I converted an old gasoline lawnmower to electric by replacing the gas engine with an electric motor and a deep cycle 12 V battery that I charge from solar panels.  I wrote a detailed blog about the construction of this mower and many other people have built their own.  While commercial cordless lawnmowers exist, they are relatively expensive, plus it is much more fun to build your own.

The original design included a voltmeter, amp meter, charging jack and circuit breaker power switch mounted near the handles.  The meters are standard automobile components, but they were unreliable and the Amp meter would get stuck often and I never really bothered to look at it very much.

An electronics parts supplier I use a lot (MPJA) has been getting in a line of digital meters that can display multiple properties and I decided to replace the old meters with a meter that can display Volts, Watts,  Amps and Watt hours.  At a cost of around $18, I consider this sexy meter a real bargain.  Click here to get a copy of the manual. 

 The image above shows the meter installed with the motor running before I took the mower for its first major test drive.  So with the blade spinning, it is drawing about 140 W and as I mowed into the taller grass, that peaked at around 250 W.

It took an hour or so to reconfigure the mower wiring to make it compatible with the meter and its current sensing shunt. 

After mowing a section of lawn for 10 minutes or so, the screen above shows that I used 34 Watt hours and the battery voltage slumped below 12 V on my brand-new deep cycle AGM battery.  This is the first time I have been able to quantify how much energy the mower actually uses!  I was watching the Amp numbers ranging from 12.5 to 20 while mowing (or about 150 to 250 Watts).

When I plugged it into the 40 W solar panel mounted to the roof of my garden shed, the voltage came back up to 12.56.  The battery is usually topped off in five or six hours of good sunlight.  Note that the display has a cool blue "techno glow" back light - not something that is very useful for device used mostly outdoors in bright light, but it sure is pretty.  I installed a power switch to the left of the meter to prevent it from draining the battery between uses.  The meter only uses about 2.8mA though, so I could just leave it on.  

6 week later
I recorded the Watt Hours (Wh) for each time I used the mower and found that I am ranging from 28 to 53Wh each time depending on how much area and how tall the grass is.  This is not a lot of power - and of course it's all free from the sun.  I also burn a lot of calories pushing this Beast around!

Solar powered motion sensing yard lights

I live in rural Maine where there aren't any streetlights and on a dark moonless night it can be hard to navigate from my parking area to the front porch.  Recently, I purchased a set of four motion sensing solar powered yard lights that I am very pleased with.  The ones I purchased were made by URPOWER, but there seem to be many manufacturers of nearly identical products that range in price from around $10-$15 each.

These clever lights require only minimal solar exposure during the day to charge up their internal battery.  And like exterior floodlights that come on with a motion sensor, these ones do the same thing but only come on for 30 seconds.  They respond to someone moving from up to 16 feet away and provide a good bright light.  This clever strategy allows these lights to be very efficient while creating a large pool of light.

I have two that are sufficient to light my front porch steps and others placed around the yard to help people unfamiliar with my property to navigate from the parking area to the porch.  I consider these relatively inexpensive lights to be a very good investment and so far they have survived six months through a Maine winter which is a testament to their hardiness.  They get excellent reviews on Amazon.

If you have an area in your yard that needs lighting, but you don't want to go to the great expense of pulling AC wiring, then this may be an optimal solution that is extremely effective.