Another M190 Microinverter failure

I was an early adopter of the first M190 microinverters made by Enphase back in 2009.  They came with a 15 year warranty that is running out in 4 years and I'm getting anxious.  These first generation units are beginning to fail often - the 8th one to fail was this week.  This is out of a total of 29 devices of that generation.  I have installed some newer ones since, and replaced the failed ones with the newer models under warranty.  Fortunately they make it easy as an installer to order a replacement via their web portal.

Latest failed microinverter as of 3/2020

This one is on the top row, so my friend and I can access it from the roof ridge and from a ladder.  It takes us less than an hour once I get the replacement part, but it's a chore that is getting old.   The price I am paying for being an enthusiastic early adopter!

8 failures so far

 For more info about my solar installation - see my very detailed blog:
http://www.arttec.net/SolarPower/index.htm

Electric room heater failed - not repairable

This afternoon I went to turn on the electric heater I use for supplemental heat in my office when it gets really cold outside.  It didn't come on and beeped sadly and the display did not light.  I really liked this heater because it had a digital thermostat that I could set, and also a timer so it would shut off after a preset number of hours.  So I tore it apart and spend 1/2 hour testing the electronics.  I could not find the failure even though it was all quite well designed.  (As a product designer, I should know!).  So sadly I had to trash it.  I just saved a few components that I could use.

The new Lasko ceramic heater I got came packed in sustainable/recyclable materials which is a plus.  (Click here to buy one - as an Amazon Associate I earn from qualifying purchases.)  Also it is very quiet so I may move it to my bedroom where I can control it from my Nest thermostat, replacing a noisier heater.  (See the post about how I built an interface to control a room heater for my Nest here.)

I hate disposing products, but if I can't fix it - nobody can!

Filling the solar collectors for my workshop solar heating system

 

 

 NOTE! I removed this system and replaced the collectors with 6 320W solar panels that will offset the 2 heat pumps I installed myself.  See this post

 

Every fall as the temperatures start dropping down to freezing I fill the collectors for my solar heating system with antifreeze solution, and in the spring I drain them.  I don't need the heat in the spring and summer.  If the antifreeze fluid gets too hot it will cause an over pressure in the collectors and also the fluid will turn acidic and begin to corrode the copper plumbing.

I mix a 50% solution of antifreeze and water and pump it from a 5 gallon bucket into the collectors and then run the pump long enough to purge air from the system.  Air bubbles can stall the pump and that is a big problem that can cause over heating.

Each year I note when I fill and drain the system on the wall of my 80 gallon storage tank (which is a regular water heater used just as a holding tank for solar heated water).  And yes we have a 7 to 8 month heating season in Maine!

Today it is cloudy and I don't expect any sun.  My system controller (that I manufacture - click here to learn more) shows 83F at the collectors and 121F at the top of the tank.  The tank temperature is high due to the propane backup that maintains the tank at 110 to 120F.  The collectors can heat the tank up to well over 180F on a good day and that is the free solar heat that I use to warm my workshop and office.

You can see a detailed blog about the design and construction of my solar heating system here. 

Here's a system diagram - click here or on the image to see live performance data.

Failing 1st generation microinverters

10 years ago when I began installing my solar power system, I was one of the first to use the new technology of microinverters made by Enphase.  (Details of my installation here).  These are small devices that convert DC solar power to 240VAC in a small box mounted behind each panel.  Original model shown above, and new one shown below.

I was a very early adopter, mine was the 1239th system commissioned back in 2009.  Now there are millions of systems, and they are up to 6th generation technology. The devices come with a 15 year warranty and I'm at the 10 year mark and have just replaced the 7th failed unit out of a total of 32.  I am able to see which ones failed from the web interface that reports performance in near real time.

It is a chore to climb up on the roof with a friend and 2 long ladders.  We have to remove the 30lb solar panel, set it aside, remove the failed microinverter and replace it, then replace the solar panel.  It takes up to an hour to do this safely and carefully.

What I really like about this system is the granularity.  I can see the performance of the system on a per-panel basis and failures are easy to spot.  And I can scroll through the recent day or week to see how the system is performing.  Below is overall power for the last week with peaks at around 4kW.

I'm hoping that Enphase will continue to replace them if units fail after the 15 year warranty.  Despite these setbacks, the system is performing very well and I am powering my home, workshop and Chevy Volt for free for up to 7 months of the year.

The pattern of failures is interesting, they seem to propagate over time:

Cordless yard tools

Someone who does not know me well asked me by email if I could repair the engine in her weed wacker.  I bit my tongue and politely replied that I don't use gasoline powered yard tools and would not choose to repair one even if I could.  I urged her to see this as an opportunity to go cordless and reduce pollution and emissions.  

The EPA says that: "A conventional lawn mower pollutes as much in an hour as 40 late model cars for an hour."  Plus I don't like the stink of gasoline or the awful noise.  Cordless yard tools are now in their prime and very affordable.  You can buy them at almost any hardware store.

Shown above are my Black & Decker 20 Volt cordless hedge trimmer, weed wacker and my home made monster lawn mower.  The hedge trimmer I refer to as a "Light Saber" - I can just wave it near anything less than 1/4" and it cuts right through without slowing down a bit and can chew through up to 1/2" branches.  The weed wacker is also very powerful.  Both tools last over 20 minutes on a charge which is plenty for home use.

Back in 2005 when I built my cordless lawn mower, there weren't many options for cordless lawn mowers, but they are common now thanks to advancing lithium battery technology that has driven the costs down dramatically. 

If you are a curious/nerdy person, you can read about my electric lawn mower construction in my detailed blog: http://www.arttec.net/Solar_Mower/index.html  It was featured in Popular Science Magazine in July 2008 and I inspired several people to do similar conversions of lawn mowers.  Mine is very powerful and can charge through tall grass with impunity!  It has a 22" cutting path while cordless models range from 14" to 21".
 
Popular Mechanics recently reviewed 6 best cordless lawn mowers for around $500.  Read the full review here.  Or this excerpt:
 "The benefits of a battery mower are obvious from the moment you engage the operator lever: They’re incredibly quiet. Gas-engine mowers succeed because they produce so much power that they can afford to waste most of their output as noise, heat, and friction. With battery mowers, that output occurs at the power plant, not in your yard. These mowers are also mechanically simple. There’s no electric start or recoil start, either—just push a button to power it up. Like any electric machine, basically it’s on or its off. There’s no engine oil, spark plug or air filter to change. Keep the battery charged and sharpen the blade. That’s all there is to it. As with cordless power tools, you charge a battery separately from the tool or machine, which allows you to simply swap out the battery when it’s dead and to keep on working."

Water heater maintenence - drain bottom and check anode rod

There are 2 things you can do to extend the life of your basic tank style water heater.  One is to periodically connect a hose to the drain valve and flush out the sediment at the bottom of the tank for a few minutes - or 4 to 5 gallons.  This prevents the sediment from building up and potentially damaging the heating elements or blocking the drain valve.  Here's a video that explains exactly what to do.  https://youtu.be/TCFCwldQHAs

The other thing is to check the anode rod.  This is a sacrificial magnesium electrode inside the tank that slowly dissolves to prevent the tank lining from rusting.  It looks like a long metal rod made of aluminum or magnesium.  Replacements cost from $17 to $45 depending on type and size.  Here's a link to get one from Amazon (as an Amazon Affiliate, I earn from qualifying purchases.)   I check my rod every year.  This process will likely require 2 strong people and a 1/2" ratchet wrench with a 1 1/16" socket.  Here's a video on how do do this: https://youtu.be/wzecqGyCllU

I used a long piece of pipe over the end of my ratchet wrench to get enough leverage to break it loose.  

Here's what my rod looks like after 2 years:

I took it outside to hose off the gunk before I replaced it.  I think it is good for another year or two, but I will check it every year. These simple maintenance chores can more than double the life of your water heater and save you a lot of money!  And from a sustainability perspective you are keeping the water heater out of the landfill.  If everyone did this there would be a lot less old tanks being disposed of.

 

Update: November 2023

Today - 4 years later I checked the rod and found that it had  rusted through to the steel which is very concerning since the tank can start rusting out at this point.  Shown below is the old and new flexible rod which is easier to install in a low ceiling basement:

 

 

Basement Watchdog water leak alarm

If your tank springs a leak - you need to know about it right away!  After my first tank failure I installed this Basement Watchdog in the drip pan under the heater.  (You DO have a drip pan right!?).  If the electrodes get wet a LOUD alarm goes off.

I got this one on Amazon, here's a link. (As an Amazon Affiliate, I earn from qualifying purchases.)

I installed the alarm on the wall outside the utility closet, and the sensing electrode in the drip pan:

Alarm on the wall

View of the electrodes

View of electrodes in place

 

Solar fountain

 

I had been considering putting out a bird bath for a while when I came across this solar fountain on Amazon for under $20.  (Click here to purchase on Amazon - As an Amazon Associate I earn from qualifying purchases.)  It was irresistible!  A fountain water feature for my lawn and it runs on it's own solar panels!  I got a plant tub and filled it with water from my rain barrel - and top it up every few days.  The sound of water tinkling is delightful.

I installed toothpicks into the foam edge to keep the fountain centered so the water does not get thrown over the edge.

It comes with different nozzles for various spray shapes and just floats perfectly on the water.  When there is little sun due to clouds or time of day, it pulses in little squirts, but in full sun the fountain goes up over 12".

Controlling a portable electric heater with a Nest Thermostat

Nest E thermostat with heater and control box

My love affair with the Nest E thermostat continues (see previous post).  I acquired a second one for about $80 for use in my bedroom that is heated exclusively by a portable electric heater. I'm using a 1500W Pelonis Safe T Furnace with a ceramic heater core that works very well.  Apparently these heaters are classics now - I have had mine since the 1980's! 

Pelonis heater and my relay control box

The relay box contains a 24VAC relay rated for 15 Amps and a 20 Amp circuit breaker.  I wired it with a 12 gauge power cord and a 3-prong grounded outlet for the output.

inside my thermostat relay control box

I put a neon indicator next to the outlet so I could be sure it was switching.

Here's the schematic:

This should work with any thermostat, but use at your own risk.  It is important to use 12 gauge wire in the box and power cord to carry the high load, and I felt better putting my own 15 Amp circuit breaker inside.
Among the things that I have learned to love about the Nest are that it automatically adjusts for daylight savings.  But also it can set back the temperature when I leave home by using the IFTTT app.  Plus it could not be easier to use, program and adjust.  And of course I have connected it to Alexa so I can adjust the temperature by voice command and from my phone from aywhere.

NEST thermostat for my Rinnai monitor heater

I heat my home in rural Maine with a combination of a DIY installed heat pump, propane and a large wood stove.  (Since installing the heat pump in March 2121 the propane is now used only as a backup).  I have 2 Rinnai monitor heaters - one in the living area and 1 in the guest bedroom.  The wood stove in the basement is capable of heating the whole house, but I only fire it up when the temperatures drop below 20F which is often in the winter.  This strikes a balance for me of cost and performance - and carbon footprint.  I cut and split about  20-30% of my firewood from my own property here in rural Maine

I have been exploring different ways of controlling the big propane heater in my living room.

It's a 20 year old model that has a manual switch that you push-on/push-off and a simple slider to set temperature.  

A while back I built an interface that allowed me to use a regular programmable wall thermostat to operate it by replacing the power switch with a relay, and that worked relatively well.  But my schedule is erratic and I wanted the option of remote control.  The NEST thermostat E is a very appealing thermostat, but I had considered it too expensive until I found a used one one on eBay for about $80.  (The newer E model lists for $169, and the previous one is $249 and these prices are way more than a regular programmable thermostat that sell for $45 to $65.)

Here's the hookup info for the relay I used to control my heater.

I used a 24VAC power adapter that I got on Amazon that is sold specifically for home thermostats. (As an Amazon Associate I earn from qualifying purchases.)

I also bought a 24VAC relay from Digi-Key (their part number: Z9722-ND ).  It was pretty simple to hook these items up with the 25ft. of wire that came with the adapter.  I did have to get inside the heater and install the relay in there, and it was not something I would recommend for anyone not experienced with wiring or electronics.

This setup works really well for me.  Here's what I like about the Nest in particular.  First, I can control the thermostat setting from anywhere using my phone.  The user interface is excellent and it is extremely easy to program a schedule.

I also like that I can review the history that shows hours of operation per day and the individual cycles.

And the main screen could not be simpler:

Since I have installed an Alexa echo dot, I can say: "Alexa, set the thermostat to 68" and she set's it instantly.  This is nice if I decide to get up earlier than the scheduled time because I can use the 2nd echo dot in my bedroom to turn the heat up before I go downstairs.  Or, similarly if I decide to knock off work early I can set it from my office using the app.

Another clever feature is that the Nest can be programmed to set the heat back if I leave home.  It uses the IFTTT app to geolocate my home and can tell when I leave the area.  Overall I could not be happier with the Nest and all its features.

In my next post I show how I built an external relay box to control a portable electric heater from the Nest E.

Energy efficiency and cost to operate of appliances

humidifier with data logger

In my last post I talked about a new humidifier I purchased after careful deliberation.  (As an Amazon Associate I earn from qualifying purchases.)  You see, when I add an electrical appliance to my home I give very serious thought to how much energy it uses and what that will cost.  By cost I mean actual dollars per month, but also the cost to the planet when considering carbon footprint of the emissions needed to power it.  For most of the year my solar power system covers all my electrical needs, but due to the lack of sun hours in the winter, I do use utility power.  I write this blog to raise awareness for those who do not yet have solar or other renewably sourced electricity.

When I got the humidifier, I took a basic set of energy readings and found that it uses 16 to 24 Watts depending on the setting.  I generally use the middle setting that uses about 22 Watts.  As such, this is an extremely efficient humidifier.  Since I only use it for 8 hours each night in my bedroom I assumed the cost would be quite low.  A quick calculation showed that it would use 5.2kW/month if used every night (which I don't).  I pay about 16 cents/kW here in Maine - so my monthly cost would be about 84 cents.  Not bad!  And here in New England our utility power is sourced partially from renewables (it's around 40-50% currently) so the carbon footprint is modest.

Data logger showing Watts of humidifier

But wait! There's more!  This particular humidifier has a humidistat (showing 20% in the image above), so it probably cycles on and off as needed to maintain the 40% humidity I prefer at night.  So I connected my data logger to the power cord (see image at top of the page) and logged readings every second for one night.  Here's what I saw:

At first glance it seemed like it was jumping from 20 to 22 Watts all night.  But let's zoom in on that data:

Aha! Now we see that it is cycling on and off with a duty cycle of roughly 45-50% and dropping down to a baseline of about 5W to power the electronics.  (That's actually about 2W - my logger calibration is a bit off).  So the actual cost is around half what I had calculated.  Neat!

Lets look at the cost calculations.  To get the monthly cost I started with the actual Watts and multiplied it by hours/day to get daily Watts used:
W per Day = W X Hours per day  (22 X 8 = 176)
Then multiplied that by 30 to get Watts per month
W per month = W per Day X 30  (176 X 30 = 5280)
This can be expressed as 5.28 kWh (we pay the utility company by the kWh)
Here in Maine I pay 16 cents/kWh, so I just multiply
$/month = kWh X $/kWh (5.28 X .16 = 84.48 cents/month)

But thanks to my data logger, I see that in reality I'm using about half that or less than 43 cents if I use it every night.  So even in the winter when I use utility power, the carbon footprint of this humidifier is relatively token especially when compared with all the other types (evaporative and steam) that use MUCH more power.

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Data logging refrigerator power

Since I had got my data logger out, I decided to log some other appliances.  Generally the biggest energy using appliance in a home is the refrigerator and my 20+ year old one is relatively efficient.  Shown above is my data logger connected to an adapter cable that can measure AC current in Amps that is  converted to Watts in the logger.  And yes, that cool blue night light doubles as a Volt meter - I'm really that geeky!

As you may know, your fridge does not run all the time.  Typically the compressor will be on about 25-30% of the time, and that is illustrated by my log above. The on time is about 10 minutes, an it's off about 33 minutes.  Those big spikes represent the starting energy of the compressor - they only last about a second and the utility meter can't respond that quickly, so it does not factor in to my energy costs.

So here's the math on the cost to operate my fridge
300 Watts X 24 = 7200W/day (if always on)
7200W X .25 = 1800W/Day = 1.8kWh (actually on 25% of the time)
1.8kWh X 30 = 54kWh/month (30 days)
54kWh X 16 cents/kWh = $8.64 per month (your cost per kWh will be different).

So if you use a KillAwatt meter or any other energy monitor to try and calculate your energy cost for a given appliance, you should always leave it running for at least 24 hours to get the average power usage.  Just looking at a power meter in the moment can give you a false impression of actual power consumption.

At the low end of the power spectrum is this heated cat bed that I got recently for my 16+ year old cat Maxx.  She loves it and stays in it all the time.  It is rated at 4 Watts and the surface temperature is just a few degrees above ambient.  I measured 73F with my thermal camera while she was not in it:

When I connected it to an energy monitor, I saw actual readings of 3.5 to 3.7W. Here's the heating pad inside:

Since this in on 24/7, it uses about 2.66 kWh/month at a cost to me of about 42 cents.  It's a small price to pay to keep Maxx happy in her old age.  And she really likes it a lot!