Posts Tagged ‘solar thermal’

Another backwards approach to solar?

January 30, 2011

Following yesterday’s post touching on the wisdom of addressing energy-efficiency before tackling renewables, here’s another example of what appears to be a backwards approach.  (And again, thankfully this is not one of our customers!)

In this photo, buried under the snow, is an even bigger solar thermal array than the one shown yesterday.  And on the roof we see not only some snow melt problems which suggest a heat loss problem, but also the makes of an ice dam problem.  Looks like someone missed insulating a couple of bays.  We sure would like to see the basic integrity of the house addressed before installing what was likely a pricy solar system.  When there are weakness with the home’s air-leakage and insulation, the savings from efficiency generally make more sense than trying to solve the problem with renewables.  Plus, the more efficient the home is, the smaller the solar system you need.  Again, it pays to think “efficiency first”. 

If you’re thinking solar, it’s wise to start with a good home energy audit and tackling many of the energy savings opportunities before investing in solar.

What’s wrong with this picture? Efficiency before renewables usually makes the most sense.

January 29, 2011

Thanks to GreenHomes America’s Home Performance Training Manager, Jason Todd for passing along this photo which begs a few questions.  When we’re looking at home energy, we like to focus on energy efficiency before we starting adding on renewable energy sources like solar and wind.   As Brett Knox likes to repeat “Reduce before You Produce”.  This picture suggests that someone may have taken another path.

We’ve certainly talked a lot about icicles and ice damming here.  And the summary version is they are not good and indicate you’re wasting energy and money.  The snow melt patterns on the roof and the icicles suggest that this house is losing a lot of heat through it’s attic and roof.

The cost to correct this (with good air-sealing and insulation details) on most homes is generally less than the cost of a solar hot water system as pictured here (partially buried under snow in the center of the photo).  And the energy savings,  carbon reductions, and other benefits, are typically greater with the efficiency measures than with this system.  Further, correcting the heat loss problem helps prevent the possible roof and structural damage that can result from ice build up.  This is a case where the economic, environmental, and comfort advantage of efficiency make a lot more sense than starting with solar.

Don’t get me wrong.  I’m a fan of solar, and we install it.  Solar hot water makes sense for a lot of people, and it is a great entree into renewables.  Most of the time, though, renewable energy makes the most sense AFTER you’ve taken the low hanging fruit offered by energy-efficiency.  Efficiency First!

[BTW, regarding solar hot water systems, in many cases I prefer the flat-plate collectors show in this video, over the evacuated tube collectors pictured above.  Flat-plate collectors  tend to be less expensive, more durable, and we’ve seen fewer issues up north with snow building up and inhibiting the collector.  Conversely, a lot of people report that snow collects around the nooks and crannies of the evacuated tubes and doesn’t shed off easily.]


Solar hot water can be a smart option.

September 1, 2010

Scott Adams’ WSJ article continues to keep me thinking… in it he talks about the solar photovoltaic array he installed on his roof, and his disappointment with the results, or rather the lack thereof. According to Wikipedia, Scott lives in Pleasanton, California. If you’ve ever been to Pleasanton you’ll know that it is a fairly sunny place with a pleasant climate (perhaps why it’s called Pleasanton). A photovoltaic array probably seemed like a good idea. An even better, and less expensive, idea might have been to install a solar hot water system on the roof.

Solar hot water can be a great entree into renewable energy

Pleasanton has an average temperature of about 63 degrees Fahrenheit, which means the water that comes out of the taps is around that temperature. This is because water pipes are buried a few feet below the surface of the ground, where daily fluctuations are negligible and seasonal effects are minimal due to the insulation afforded by the soil. If you want to know the average temperature where you live, stick a thermometer in a glass of tap water (taken after the faucet has been flowing for about a minute), it should be fairly close in the lower latitudes of the continental US. If you live up north you will probably notice some seasonal effects (i.e. your tap water is a little cooler in winter and a little warmer in summer).

The upshot of this is that in Pleasanton homeowners typically use fossil fuels to heat water from ~63 degrees to the temperature of choice for clothes washing, dishwashing and showering, somewhere around 100 degrees. Solar hot water lets the sun to do some of the hard work – heating the water from 63 degrees to say, 90 degrees – and relies on fossil fuels to kick in for the final push to ~100 degrees. In this example the sun has done almost three quarters of the work, which would reduce your expenditure on water heating by almost three quarters.

Solar hot water can reduce water heating expenditure by nearly 100% in favorable regions in the summer months. In Pleasanton we would expect annual saving to be on the order of ~70 – 75% of water heating costs. Given that 14 – 25 % of energy consumed in the typical home is used to heat water, this could result in significant savings.

Of course the suitability of your house for a solar hot water system depends on many factors and only a qualified professional, such as those at GreenHomes America, can tutor you on the best options for your building. Having said that, here is a link to a quick video tutorial on solar hot water from our V.P. Mike Rogers.

Solar Hot Water–Warm Climate Simplicity

March 6, 2010

While in Mexico last week, I noticed a smart solar hot water collector on many buildings.  In a climate with little chance of freezing temperatures, solar collectors don’t not freeze protection, and this simplifies things considerably.  As long of the roof is strong enough, a large black tank will do the job.  Cold water comes in, hot water goes out.  And the consderable mass holds the heat through the night.  There are some design limitations, but this is a simple, inexpensive approach that can be adopted broadly in warm climates.

ACEEE Hot Water Forum

June 8, 2009

I’m meeting with industry experts and utilities today at the ACEEE Hot Water Forum on new water heating technologies and iniatives–a good part of the conversation will be about solar hot water.  I’ll let you know if anything interesting comes up.


Solar hot water video

June 3, 2009
Click for Solar Hot Water Video

Click for Solar Hot Water Video

We’ll be putting together a series of informational and educational videos beginning this summer.   It will be several weeks before we launch, but I thought it would be fun to share the simple concept piece we put together.   Crunching the numbers on solar hot water systems, I’m really excited about them, and I thought we’d start with that to flesh out the video idea.

[Click on the video at:]

And my commitment to you—in the future I’ll try to keep it below 10 cups of coffee per day!

P.S.  As GreenHomes’ blog readers know, my mantra is “efficiency first,” before renewables.  But if you’d like to learn a bit more about solar thermal visit our website or dive into our blog archives here:



April 14, 2009

A few weeks back on Sunday I was listening to This American Life on Vermont Public Radio, and within the context of the story line, the topic of what constitutes a ‘good career’ came up, the gist being that learning a trade in our new economy is on par with getting a degree in electrical engineering (like I did more than twenty years ago).

Based on what I’m seeing at GreenHomes America, and more generally in our industry and economy, I think the NPR folks are on to something real and substantial. The home performance category is creating jobs for engineers, for tradespeople, and for the office staff that support them. And when you consider the pent-up demand for home performance services, there is more work out there than GreenHomes can service, or that any of the existing home performance contractors can service right now.   Energy-efficiency first, and then renewable energy down the road, we’re going to see a lot of new jobs created in this sector. 

And these are good jobs! Unlike many white-collar jobs (engineers, accountants, marketers), these jobs in our industry are secure. They can’t be outsourced overseas.  Homes need to be insulated and air-sealed here.  High-efficiency heating, cooling, and ventilation equipment can only be installed onsite.  Solar thermal systems get installed on our roofs.  The work needs to be done right here, locally.   And these are year-round positions, offering good benefits, long-term employment opportunities, and a skill set that will prove valuable for many years.

Especially in light of the recent volatility in our economy, I suspect many people are thinking differently about what a ‘good job’ is. If job security, learning a valuable skill that will be in high demand for many decades to come, steady income growth, and geographical diversity sound good, a trade job in home performance stacks up pretty well.  

A generation ago, parents urged their kids into white-collar office jobs. Today, they may do well to consider a broader range of options, and “green-collar” looks pretty good.


Solar hot water…for cooling!

April 6, 2009

I’ve talked about solar thermal (in this case, solar hot water) before.  At GreenHomes we’re excited about the elegance, simplicity, and bang-for-the-buck of these systems generating hot water very cost-effectively for homeowners today.


The systems we use work great, and our customers are very happy with them.  They would be even better with a way to increase their size even further but get rid of the “extra” heat during the sunny summer months when the system would otherwise generate too much heat.  One way to do this is simply “dump” the heat somewhere.  But on the near horizon is the ability to use this waste heat to actually help provide cooling!  That’s right, the heat from the sun being used to air-condition your home.


EnerWorks, the manufacturer of the flat plate collectors that GreenHomes uses, has already taken a bold step forward with its technology now powering the largest solar thermal heating and cooling installation in the world.  The installation in Fletcher, North Carolina provides solar thermal heating and cooling for an industrial/commercial warehouse and offices.  [For some of the technical details, see the EnerWorks background piece on this project.]


Solar thermal cooling isn’t quite ready for smaller scale residential projects, but people are working on it, and it should be coming in the next several years.  Fortunately, the heating technology is mature and robust and homeowners can start enjoying the benefits of using the sun to heat most of their water right now very cost-effectively.  This system we use is fully certified, ENERGY STAR® qualified, and the only system meeting CSA international standards.  And the new tax credits make going for solar hot water even easier.


Contact GreenHomes to see if solar hot water makes sense for your home today.



Solar Energy Monitor Goes Wireless

February 9, 2009

One of the things many hybrid car drivers like is the monitor on their dashboard that show how many MPG they’re getting at that moment and averaging over time.  In fact, this monitor may actually help increase the MPG as it helps drivers adjust their habits slightly (or drastically!) to get better mileage.


tem-homepgThat same idea is being applied to home energy use.  I will save discussion of whole house dashboards for another day.  But it’s clear from the new monitor we use on our solar hot water, that this technology makes a lot of sense.  It allows you to see the savings you’re getting in real time, from anywhere in the house.  With the portable, hand-held device, you can see results such as daily, monthly, annual and lifetime dollar savings, the energy collected, and the reduction in CO2 emissions as solar energy displaces the gas or electric you would normally use to heat your water.  You can also read parameters like the temperature of water coming us the collector and of the water you’re heating.  Kind of neat to see the 140 degree reading on a day when the outside temperature is below freezing!  


As we’re seeing, solar hot water is ready for the big time!



Shedding Light on Solar Hot Water

September 12, 2008

At the ACEEE conference, there was attention given to solar hot water—a technology that is big in Europe and now even required in Hawaii.  Using the sun to heat your water is great for the environment and for your wallet! Especially with today’s skyrocketing energy costs! You can save up to 75% on water heating costs with a professionally installed solar system.

You don‘t have to live in sunny Arizona to benefit from solar. Even in cloudier locations like Syracuse or Seattle or Canada, a solar hot water system can help meet your hot water needs!

Another myth among homeowners is that solar hot water systems are too expensive to install. For example, in New York, there are currently generous tax credits and incentives that can put 65% or more of the system cost back in your pocket! Depending on what you use now to heat your water (gas, oil, electric), how much you‘re paying for that fuel, and how much hot water you use (and if like me you have teenage daughters, the answer is A LOT!), you can recoup the cost of the system in as little 3 to 5 years. After that, it‘s money in your pocket!

So how does it work? Solar hot water systems are usually used to heat water for basic household needs such as laundry, bathing, dishwashing, and cooking. These systems use solar energy – gathered from solar collectors usually mounted on your roof – to preheat water coming into a standard water heater. The warmer the water from the solar heater, the less conventional fuel is needed to provide for the household‘s hot water demands.

During the summer, a properly sized solar hot water system can provide up to 100% of a household‘s needs! In the winter, it will be less in snowy climates. On average, however, solar hot water systems meet between 60% to 70% of a home‘s annual load.

Solar systems not only save you money on your energy bills, they also increase your energy independence and decrease your environmental impact.   Visit the GreenHomes site to see if solar hot water is right for your home.


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