Monday, January 28, 2019

Solar power backup - my dirty little secret

When I tell people that I have a solar powered home they tend to assume that I have battery backup for power outages.  I don't.  I have a grid intertied system, so any excess power I generate gets fed into the grid for which I get a credit under net metering rules.  In essence the grid is my storage, because I can use up that credit in the fall and winter.  When the power fails my solar power system shuts down to prevent my power from back feeding into the grid and harming line workers (this is a federally mandated safety system).   

By not having a battery I have to use a different strategy to survive the winter storm power outages that average 3 days each year here in rural Maine.  Some outages have run over 7 days, while other are just a few hours.  I need power to run my home based business, well pump, heating systems, refrigerator etc.

Since my solar power system is not designed to incorporate battery backup, I decided to install an automatic home backup generator that runs on propane.  This generator starts up in 15 seconds and powers my whole property - house and workshop. Yes, I'm burning fossil fuel to generate power!  But the cost performance trade-offs made sense at the time.  

My 5kW Generac generator only cost me about $2500 in 2009 from Home Depot and has 700 hours on it as of January 2019.  I installed it myself and do most of the basic maintenance, but also pay for maintenance and repairs as needed.  The cost of installing a large battery bank would have been more than double my modest investment.  Lead acid batteries need frequent maintenance and replacement every 5-7 years and the cost just did not make sense to me.  Batteries also have a very finite amount of energy storage lasting maybe a day or so without recharging whereas the stored propane in my tanks can provide power for almost 2 weeks if needed.

After every snow storm, the first thing I do is clear the solar panels and collectors - even if the power did not go out.  If the power did go out, the generator turns on with in 15 seconds.  I want to get as much free solar energy as possible.  So I have a long snow rake that I use to remove all the snow - usually in the morning before the sun hits the panels.
time-laps video fo snow clearing
Click the image to see a time-lapse video of me clearing the snow on my property and solar panels in February 2018. 
There has been a change in the solar industry in the last year or so.  They are now offering home battery backups - whether or not you have solar power.  This is due the the plunging costs of large batteries like those use in electric vehicles.  Enphase, the company that makes the microinverters that I use have introduced just such a system, and there are many others like the Tesla PowerwallClick here for details about the Enphase battery system.  And click here to read an informative blog post from Energy Sage about Tesla Powerwall cost realities.  At some point I hope to install a system like this, but for now it is beyond my means.

Sunday, January 27, 2019

First major boiler repair since I installed it in 2001

The solar augmented heating system I designed and built for my workshop back in 2001 has performed very well (details on my web site).  Maintenance has been minimal as far as the equipment itself is concerned the only part that failed was a pressure tank in 2010 which was easy to replace.  The boiler is only used to augment the stored solar heat in the 40 gallon storage tank so it rarely is running full blast.  It just needs to add enough heat to bring the temperature up to 140F for my radiators.  On a typical sunny day in winter the water in the storage tank is over 150F by the late afternoon.  As that gets drawn down to about 110F the boiler makes up the difference.

A week or so ago I noticed that the exhaust blower for the Bosch Aquastar boiler was not running and my utility room was hot and smelled like propane fumes.  The heat was due to the stalled motor that was getting really hot.  The bearings had seized so it could not remove the hot exhaust.

The Aquastar boiler itself has only required minimal maintenance over the last 18 years - good German engineering.  The blower motor has 22545 hours on it.  I know this because I put an hour meter on it to log running hours.  That's equivalent to 2.6 years of continuous operation!

I had to cut the blower off the motor shaft with a sawzall because the lock screw was frozen.  It took me an hour or so of web research to track down a replacement blower motor from one supplier and a motor from another source.  The parts cost less than $150. 

Removing it and replacing it required just a few bolts and screws, and wiring the new motor in.  The wiring in the control box was a total snake pit, but the motor only has 3 wires, so it was not too daunting for a skilled electrical engineer like me.

The new blower runs much quieter because the crud that had built up in the old one was making it run out of balance and it vibrated.
I enjoy repairing and maintaining the system that I designed and I hope that it will continue to work for many years.  Click here or on the image below to see live performance of the system.
solar heatinf system diagram

If I could afford it I would replace the solar collectors and storage tank with an air source heat pump and keep the boiler and radiators as a backup.  Heat pumps are better bang for the buck these days.  Solar collectors for building heating are no longer cost competitive both from a performance standpoint and on and return on investment.

Sunday, January 13, 2019

Rechargeable emergency LED lights

Recently I came across a new product that I have found to be helpful.  This is an LED lamp that looks like an ordinary 60W equivalent lamp (9W actual) that contains an internal battery.  The battery charges during normal usage - while the light is on.  Then if the utility power fails the internal circuitry detects this and powers the lamp for up to 3 hours (if it is switched on).  You can't test it by unplugging the light, it needs to be plugged in when the power fails.  I found a 2-pack for under $20 on-line.

As I played around with them I learned a lot.  First, they come with a socket and hook with a button switch.  This allows them to be used for camping or location specific emergency lighting.  The way they detect an outage is to sense the resistance in the electrical wiring of the house, so the switch just shorts the contacts to turn the lamp on.

You can also turn the lamp on by touching the bottom of the lamp with a damp cloth - or your fingers.  (You can also do an "Uncle Fester" and put it in your mouth to light it by using your tongue to connect the contacts). 

When powered from 120V, they  produce 60W equivalent (850 Lumens) of bright warm light.  On internal battery power the output drops to 40W equivalent (500 Lumens) which is quite bright and useful in any situation.  The battery will last 3-4 hours and you can turn the lamp on and off after a power failure just like a normal light. If it is likely to be a long outage, you could conserve power buy using it sparingly.

I tried replacing lamps in my home with varied success.  First, I installed 1 in my kitchen ceiling where I have 4 flood lights, it came on when I turned the lights off.  I think this is because it sees the other 3 regular LED lights in the circuit and gets confused.  Also it is useless with any remote controlled home automation switch because the internal relay will switch it off when the power fails.  Same goes for room occupancy sensors that will turn off when the utility power fails and can't be turned on.  So these are most useful when used in table and floor lamps or house lighting circuits with only 1 lamp.  I'm also using them in my stairwells and hallways for safety.

If I still lived in California where earthquakes could knock out power I would use them widely as emergency lights.  Here in Maine, we get outages often in winter storms and they can last hours to days which is why I have an automatic standby generator that can power the whole property for over a week running on propane.  But the generator takes up to 15 seconds to start and these lamps will bridge that gap which I find compelling.  

If you want to purchase some - just search on "Rechargeable Emergency LED Bulb" and you will find many affordable options.