Saving Electricity home As seen in Newsweek, Forbes, NPR, the Christian Science Monitor, CNET, PC Magazine, InfoWorld, and everywhere else. About  
Rebates & Tax Credits
for U.S. consumers

Incentives for installing insulation and for buying energy-efficient appliances like refrigerators, washing machines, and air conditioners are often available from local and state governments and utilities. You can see what's available at DSIRE,, and Energy Star.

Related sites:

Home Power Magazine. All about renewable energy for the home.

No-Impact Man. Blog about a family striving to have no net impact. (i.e., What little they use, they offset.) Inspirational.

Off-Grid. News and resources about living without being connected to a utility company.

Mr. Electricity in the news:

"Michael Bluejay runs the outstanding Saving Electricity site that I've mentioned many times before." —J.D. Roth, Get Rich Slowly

Deep Green (book) by Jenny Nazak, 2018
Small Steps, Big Strides: Building Sustainability Habits at Home (book), Lucinda F. Brown, 2016
How much money you'll save with these common energy-saving strategies, Lifehacker, Sep. 28, 2015
Radio interview about saving electricity, Newstalk 1010 (Toronto), April 21, 2015
How much does your PC cost in electricity?, PC Mech, Nov 21, 2013
How Much Electricity Do Your Gadgets Really Use?, Forbes, Sep. 7, 2013
Can my bicycle power my toaster?, Grist, June 10, 2013
Six summer debt traps and how to avoid them, Main St, June 5, 2013
To convert to gas or electric?, Marketplace Radio (NPR), July 20, 2012
8 Simple Ways to Reduce Household Waste, Living Green Magazine, June 29, 2012
Why is my electric bill so high?, New York Daily News, Mar. 27, 2012
Fight the Power, CTV (Canada's largest private broadcaster), Mar. 23, 2012
How to Cut Your Electric Bill, Business Insider, Mar. 20, 2012
Tips to save energy when using your computer, WPLG Channel 10 (Miami, FL), Feb. 23, 2012
How long will it take an energy-efficient washer/dryer to pay for itself?, Christian Science Monitor, Oct. 29, 2011
10 Easy Ways to Lower Your Electric Bill, Forbes, August 23, 2011
18 ways to save on utility bills, AARP, July 9, 2011
How to Save $500 Worth of Energy This Summer, TIME magazine, June 28, 2011
Hot over the energy bill? Turn off the A/C, just chill, Chicago Tribune, June 24, 2011
Cool Site of the Day, Kim Komando (syndicated radio host), May 29, 2011
This calculator shows how much you spend washing clothes, Lifehacker, May 6, 2011
What you pay when you're away, WCPO Channel 9 (Cincinatti), May 5, 2011
Spotting energy gluttons in your home, Chicago Tribune (CA), Apr. 7, 2011
Walnut Creek author has tips for livng a thrifty life, Contra Costa Times (CA), Jan. 24, 2011
Do space heaters save money and energy?, Mother Jones, Jan. 10, 2011
Energy steps to take for a less pricey winter, Reuters, Nov. 10, 2010
Should you shut down your computer or put it to sleep?, Mother Jones, Nov. 1, 2010
Energy saving tips for fall, Chicago Tribune & Seattle Times Nov. 7, 2010
10 ways to save money on your utility bill, Yahoo! Finance, Oct. 2, 2010
Mr. Electricity Ranks Refrigerators & Electrical Wasters, Green Building Elements, Sep. 8, 2010
The case against long-distance relationships, Slate, Sep. 3, 2010
10 household items that are bleeding you dry, Times Daily (Florence, AL), July 27, 2010
Cold, hard cash, Kansas City Star, June 22, 10
Stretch your dollar, not your budget, Globe and Mail, May 18, 2010
Auto abstinence, onearth magazine, Winter 2010
2010 Frugal Living Guide,
Energy-saving schemes yield €5.8m in savings, Times of Malta, Dec. 20, 09
Four ways to reduce your PC's carbon footprint, CNET, Dec 2, 09
The day I hit the brakes, onearth magazine, Fall 2009
How Much Do You Really Save By Air-Drying Your Clothes?, The Simple Dollar, 2010
Enjoy the mild weather, low electricity bills, Detroit Free Press, Jul 18, 09
The most energy-efficient way to heat a cup of water, Christian Science Monitor, Jun 16, 09
Ten ways to save energy, Times of Malta, Jan 3, 09
Measuring your green IT baseline, InfoWorld, Sep 4, 08
Bald Brothers Breakfast (MP3), ABC Adelaide, March 27, 2007
Net Interest, Newsweek, Feb 12, 07
The Power Hungry Digital Lifestyle, PC Magazine, Sep 4, 07
Net Interest, Newsweek, Feb 12, 07
Answers to all your electricity questions, Treehugger, Jul 11, 08 Going Green, Monsters and Critics, Jan 6, 2007
A hunt for energy hogs, Wall Street Journal Online, Dec 18, 06

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Solar water heating

 Last update: January 2016

No doubt about it:  solar water heating systems definitely save money in the long run, but typical payback time in the U.S. is around 7 years (vs. an electric heater) to 16 years (vs. a gas heater).  And of course, once it pays for itself, your hot water is free for years after that.  As you might suspect, Mr. Electricity's household enjoys solar hot water.  As I write this, in the middle of winter, our system is making our water nice and toasty.

Yes, solar works even when it's cold, as long as there's sun.  Even if it's freezing outside, your system can still use the sun to heat the water.  When there's no sun, your traditional tank heater will act as a backup to handle the heating.

Note that in probably most cases, it's a better deal to install solar PV panels to make electricity, and then use the electricity to power a heat-pump water heater.  (The only reason I didn't do that myself was that I had only 40sf of sunny roofspace, vs. the 110sf I'd need for a solar PV system.)  See more about this at GBA.  Before you have a solar water heating system installed, I strongly suggest you consider whether going with solar PV + a heat-pump heater will be better for your situation.

With solar PV, you can generate 100% of your water heating needs with solar.  With a solar thermal system, you won't be making all of it because the heater will use the electric backup when the sun's not shining.  The amount of heating supplied by solar is called the solar fraction, and it varies from about 50% to 85% depending on how much sun your area gets. (NREL, pp. 8,31,32)

The rest of the page is for those who are sure that solar thermal is better for them than solar PV.

Solar thermal systems

There's a bewildering variety of solar heating systems. 
The easy way is to deal with this is to choose a reputable, well-reviewed installer, and go with their recommendation.  The harder way is to learn all about the different kinds of systems yourself.  This page is for those of you who want to go the hard way.

So, let's compare the different kinds of systems.  Of course, before doing that, we'll need to learn some basic vocabulary:
  • Collector.  This is the part that absorbs the sun's solar energy.  It's usually a flat-plate collector or a rectangular grid of tubes (both of which you probably called a solar panel).  Your installer will call it a collector, so that's what we call it.  In some batch systems (more on those below) a standard water heater tank is used as the collector, but those aren't very popular.
  • Tank.  Most systems use your normal water heater tank for storage.  This lets you heat your water the normal way (gas or electricity) when the sun's not shining.
  • Direct/Indirect (aka, Open/Closed).  Direct systems heat the water you'll actually use, while indirect systems constantly recirculate the same water or antifreeze in a closed loop between the collector and the tank.  Direct is also called "open", and indirect is also called "closed".
  • Active/Passive.  An active system is simply one that uses pumps.  Most do.  The less common passive (pumpless) systems are cheaper but not good for freezing climates, and most places do freeze at least sometimes.  If we combine the two ways of classing systems, then we have Direct Active, Indirect Active, and Direct Passive.  (There's no such thing as Indirect Passive.)
  • HTF.  HTF is heat transfer fluid, which is the water or antifreeze solution that constantly recirculated in a closed loop in an indirect system.

Types of solar water heating systems
System name
D/I A/P Description Pros Cons
Batch (integral, ICS), cylindrical tank Direct Passive
The collector is the tank.  It's either a standard cylindrical tank like you're used to, or a panel of tubes.  You'll still need a separate tank as a backup, for when the sun's not shining.  Sometimes batch systems just function to pre-heat the water for the conventional heater. Simple, cheap • Freeze risk (in freezing climates)
• Overheating risk
• Scale can build up, decreasing capacity
• Most of these systems have small capacity
• Batch systems also have the cons of losing lots of heat at night (not so with CHS)
• Batch systems with cylindrical tanks make less hot water than batch w/tube collectors or thermosiphon.
Batch (integral, ICS), tube collector Simple, cheap
Thermosiphon (CHS) The tank sits above the collector, and the hot water rises into it naturally since it's less dense than cold water. • Simple
• Unlike batch systems, the collector tank can be insulated, reducing heat loss an night
Cold water is pumped up to the collector,then down to the tank.  (I don't know why the house's water pressure isn't sufficient to push the water up to the collector.) I call this one  "stereotypical" because it's probably how most people imagine a solar water heater, although it's actually not the most popular kind. • More efficient than indirect systems
• As with all Active systems, a traditional tank is used, which can heat the water with gas or electricity when there's no sun
• Freeze risk (in freezing climates)
• Overheating risk
• Scale can build up, decreasing capacity
• Pump uses ~$10 of electricity per year
Water Indirect The same distilled water is constantly circulated in a closed loop of piping  between the collector and the tank.  (That water never comes out of a faucet; it's permanently stuck in the loop.)  While in the collector, the water absorbs solar heat, then it's pumped into the tank where its heat radiates through the piping to heat the tank water, then the heat-removed water is pumped back up to the collector. • No scale buildup in the collector or the piping between the collector and the tank, unlike direct systems
• Pump uses less energy than drainback system
• Freeze risk (in freezing climates)
• Overheating risk
• Pump uses ~$10 of electricity per year
Glycol Same as with the Water system above, except it's a glycol solution (60% water, 40% glycol) that's pumped through the loop, which offers some freeze and overheat protection. • Glycol systems typically circulate some hot water from the tank through the collector for extra freeze protection in cold weather; this wastes some of the heat that was generated
• If glycol overheats, it acidifies: the acid shortens the life of the system, and acidic glycol no longer provides freeze protection
• Glycol must be replaced every 3-8 years, at a cost of $150+
• Pump uses ~$10 of electricity per year
Drainback When the tank has reached its set temperature, the pump turns off and the HTF falls "drains back" into a separate, small drainback tank, which empties the loop of HTF fluid.  This elegantly prevents both freezing and overheating. Overcomes all problems of other systems (no sediment buildup as with direct systems, no worries about freezing/overheating, HTF never needs to be replaced as with glycol systems)
• Less efficient than a stereotypical system
• Pump uses more energy than water- or glycol-based system (~$24/yr. is my estimate based on figures here)

How some of the "Cons" in the table are sometimes addressed

Direct systems:

  • Freezing.  Take your pick:
    1. Freeze-tolerant collectors (but that doesn't protect the piping).
    2. Using a pump to circulate hot tank water through the system (wastes some of the heat that was generated).
    3. Draining the system in freezing weather (inconvenient)
  • Overheating:  Heat export pump, or covering the collectors with a blanket
  • Scale buildup: Ion-exchange softener

Freezing in indirect water-based systems:  Draining the system in freezing weather, or using glycol instead of water as the HTF, or using a drainback system in the first place

Overheating in glycol system:

  1. Covering the collector with a blanket, which is inconvenient if the collector is on the roof.
  2. Setting the tank temperature higher, which will keep the pump circulating until that higher temp is reached, if ever.  This has the added benefit of increasing hot water storage, though this adds the downside of increased risk of scale buildup in the tank.  Also, if the tank does reach the max temp (easy in the summer), then you're right back to the risk of overheating the glycol.
  3. Running the pump continuously to keep the glycol from stagnating.  But this is a waste of electricity for running the pump.

Which system for which part of the country

Solar Direct has a U.S. map which shows which kind of system they recommend for which part of the country.

Figures I couldn't find

I couldn't track down any good figures for:
  1. the advantage in efficiency for a "stereotypical" system (as listed above) vs. an indirect system
  2. the reduction in efficiency in a direct system due to sediment buildup.  The closest I could get was this, which doesn't help much. I also found the "solscale" calculator, which I couldn't get to actually run.
If any readers have access to these figures, then please let me know!

To-Do List

Reminder to self:  Next time I update this page, run through the math to show the savings.

More resources

Here are my favorite pages for basic info on solar hot water.