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Solar at Home

Solar at Home


The trials, tribulations and rewards of going solar
Solar at Home Home

Tools for doing your own energy audit

The views expressed are those of the author and are not necessarily those of Scientific American.


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Editor’s Note: Scientific American‘s George Musser will be chronicling his experiences installing solar panels in Solar at Home (formerly 60-Second Solar). Read his introduction here and see all posts here.

The last piece of my solar array fell into place three weeks ago when the utility installed two new meters on my house, one that registers solar energy generation (for determining tradable credits) and one that registers net home consumption (for billing). So far, my array has produced as much as 8.1 kilowatt-hours per day, which is actually a bit more than the PV Watts calculator predicts for a system of my size (3 kW). But the job isn’t over yet. It may never be.

Fighting energy waste is a never-ending battle. In an earlier post, I mentioned The Energy Detective, which measures the total electricity consumption of your house. To track down specific power hogs, a portable meter such as Kill-a-Watt is invaluable. With it, I recently went around the house checking how much power our electronic appliances and adaptors consumed in standby mode. Bracing myself for a torrent of waste, I was pleasantly surprised that most devices drew less than one watt.

The suckiest vampire proved to be the Wii (10 watts in standby mode), so we’re more diligent now about powering it down. A handheld-vacuum charger drew three watts even when the battery was full-up, so now I make sure to unplug it between chargings. A USB hub and UPS each drew 2 watts, and we didn’t really need either, so we removed them. It’s not much, but it adds up, and it’s easy to fix.

With an Amazon gift certificate my mom gave me for Christmas, I got another handy tool: a Black & Decker Thermal Leak Detector. An affordable version of the multi-thousand-dollar thermal imagers used by professional home energy auditor, it gives temperature readings, though not full thermal images. And boy is it great! Best gift my mom ever got me.

The sensor resembles a laser-tag pistol. You point it at a surface, a readout tells you the temperature, and—here’s where it gets fun—a laser pointer changes color to red, blue, or green depending on whether the temperature is hotter than, colder than, or equal to a reference temperature (namely, the temperature of whatever the detector was pointing to when you turned it on). So you can see at a glance where heat is leaking out. A switch lets you set the amount the temperature needs to deviate from the reference for the light to change color.

The image at the top of this post shows two readings on the wall above a window in my daughter’s room. It matches the thermal image taken by my auditor. I’ve already found lots of places to caulk or insulate. Best of all, by taking before and after readings, you can see what good your efforts have wrought. For instance, the light turned blue when I passed the sensor over an outlet, so I added a sealer under the wallplate—and the temperature jumped by six degrees F. With all the work we’ve done to button up our house, I appreciate having some proof it actually does some good. 

Black & Decker thermal sensor reading in George’s house, courtesy of George





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  1. 1. georget99 8:22 am 01/4/2010

    A Kill-A-Watt is a great inexpensive gadget, but I’m not too sure of its accuracy in the very low range. It’s like trying to weigh a letter with a bathroom scale.

    Link to this
  2. 2. lakota2012 11:31 am 01/4/2010

    "To track down specific power hogs, a portable meter such as Kill-a-Watt is invaluable." — George
    —————-

    Yes, I’ve been using one for years in my off-grid applications, but did find out the hard way that it is only rated at 15 amps.

    I find the accuracy good even in the low range of LED xmas lights, and especially telling with DirecTV/Dish satellite receivers pulling 20-50 watts even when OFF! Our DirecTV receiver uses less than half our neighbor’s Dish Network receiver, despite both being relatively new HD units!

    I usually get 6+ kWh’s per day with my 1,800 watt array, so I’m curious to the size of your array producing 8+ kWh/day.

    Link to this
  3. 3. Michael Hanlon 1:09 am 01/10/2010

    Performing one’s own audit and developing a more complete image of the structure of one’s energy expenditure is essential to reducing waste of resources (both natural and man-made). I had my POCO come and do a free audit on my house several years ago. I was informed that a flat roofed addition to the building didn’t have insulation and that if I added it (sevewral thousand $ investment), my consumption would drop by 10%. Instead of insulating or putting an absorptive black tar on it the next sealing iteration, I used white elastomeric coating. I could tell the difference immediately on the inside, Recently, I needed to take down a small section of that ceiling under the flat roof. Damn if it weren’t insulated! The POCO had made their statement based on the fact that our local building codes didn’t require insulation and assumed it wasn’t there! Assumed in a professional audit!
    I’m sure glad I hadn’t contracted to have blown in insulation installed (Their suggestion)

    Link to this
  4. 4. lakota2012 3:43 pm 01/11/2010

    I see that George Musser is both unable to answer questions to him here in the comment section or through his e-mail. That is just plain poor PR for SciAm and their writers!
    —————

    It appears that both Microsoft and Google are plugging-into the Energy-Monitoring Market, since both are testing Web-based applications that help consumers monitor their energy consumption and make more informed energy choices.

    Currently in beta-testing mode, Google PowerMeter is a free opt-in service that interacts with "smart meters" or electricity management devices provided by utility companies. At the present time it is only available to a select group of utility customers including San Diego Gas & Electric, TXU Energy in Texas, Wisconsin Public Service and White River Valley Electric Cooperative in Missouri. More at:
    http://www.google.org/powermeter

    Likewise, Microsoft’s Energy Management and Home Automation Group, has partnered with four utility companies to offer a free online tool called Hohm that allows consumers to keep tabs on their monthly electrical power and gas usage. More at:
    http://www.microsoft-hohm.com

    Link to this
  5. 5. Michael Hanlon 5:08 pm 01/11/2010

    Lakota: GM is covering an Astronomy conference in Washington DC. That fact may have an impact on his availability.

    Link to this
  6. 6. gmusser 9:54 am 01/12/2010

    Indeed that was the reason for my silence. I have edited the original p0st to indicate my system size.

    Link to this
  7. 7. lakota2012 11:34 am 01/12/2010

    George, thanks for the edit to show your 3 kW system. Appears that my 1.8 kW system producing 6+ kWh/day must get a bit more sunshine in CO than your 3 kW system producing up to 8+ kWh/day in NJ.

    I see that Aleo is claiming especially high power production from their PV panels, and that Sanyo says that their HIT Double bifacial PV panels produce up to 30% more power, and that Evergreen has always advertised more power on cloudy days — but I certainly like my BP panels for consistency!

    Link to this
  8. 8. gmusser 11:47 am 01/15/2010

    Impressive. What does PVWatts predict for a system of your size, exposure, and latitude?

    Link to this
  9. 9. SolarGolf 1:36 pm 01/29/2010

    It seems that everywhere you turn you are seeing more and more Solar products beginning to emerge. One of the latest trends that is hitting the Global Market is Solar For Golf Carts. Many Golf Courses are taking the Eco-Friendly approach to their Golf Courses by using recycled water, biodegradable materials, Chemical Free pesticides and fertilizers to name a few. But the Newest and most fascinating is putting Solar Tops on the Golf Carts!

    May 2009, Sebonack Golf Club in Southhampton, NY converted 39 of their 40 Golf carts into Solar. Earlier in the year, the Jockey Club Kau Sai Chau Public Golf Course in Hong Kong became the first club in the world to outfit it’s entire fleet of golf carts with Solar Tops. Both claim an annual savings of over $50,000.00 US by going Solar. Hawaii Prince Golf Club has also converted 10 of their golf carts.

    The impact this is having is not only the reduction in their Carbon footprint, but the reduction in downtime for their golfers and the savings on electric costs because they do not have to plug in as often. And one of the greater advantages to going Solar is the extended battery life. The costs savings become tremendous as well as continuous.

    SolarForGolfCarts.com has opened the doors for the international market as well with their distributorship in Turkey and Panama.

    This is definitely a trend worth watching. And encouraging for those of us who look to business’ that become more Eco-Friendly.

    Link to this
  10. 10. Michael Hanlon 5:28 pm 03/8/2010

    Has the Sun gone out? I’d have hought that such a subject would be done to death by Scirentific American.

    George Musser, is everything alright on your end? Five weeks of inactivity has at least one of your faithful readers wondering about this situation. I need my fix of "Solar at Home".

    Link to this
  11. 11. Michael Hanlon 12:31 am 03/15/2010

    This space should be starting to heat up again after the two recent articles posted at the SciAm Observations forum. Cheaper cells coupled with liquid metal storage. A marriage made to divorce us from the grid structure we now use. See, methods of energy storage are the key to our future. Although I still have a hankering in my wants for a good old fashioned fly-wheel with pin-wheel impellors. Ah well whatever we can mass produce efficiently, safely and with good stewardship of the environmernt is okay by me.

    Link to this
  12. 12. jjbaulikki 11:03 am 08/15/2010

    The Kill-A-Watt is cheap for a reason. 15 amp limit and cannot do 220V appliances. Do it the right way and have a qualified electrician come out and do a complete analysis on the home. The is the only way to do a real home energy audit for electrical consumption.

    <a href="http://www.energyauditortalk.org">Home Energy Audit</a>

    Link to this

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