Yes, we are still giddy about the new master bathroom, but need to move forward on some of the renewable energy/systems research for our Green Harlem Brownstone renovation. Next up is Solar Hot Water and Heating. (We have some experience with Solar PV for generating electricity, and will cover another time.)
Most people don't realize that you can use solar to heat domestic hot water, as well as use it to heat water for radiant floor systems (which are basically tubes with hot water flowing through them under your floor). One of the most efficient ways to use solar energy is to heat hot water. 
Traditionally, a flat-panel type of collector was used - a box with a dark covering that absorbed heat. These systems don't generate heat on cloudy days, and are severely affected by the angle of the sun.
Recently, new technology called evacuated tube solar collectors has reinvigorated the solar hot water industry.
They are a series of glass vacuum tubes with thin strips of heat-absorbing metal inside. 
They are unaffected by weather (down to -50 degrees) and can have an efficiency rating of 70-80%. Yes, they are a bit more expensive, but can almost double the capacity of a Solar Hot Water system.
There are two leading candidates, SunMaxx and Thermomax. The SunMaxx Solar system costs roughly $3,000 for a 120 gallon a day system. Hopefully that is large enough to offset a good portion of our heat and hot water needs.
Thermomax wants me to "call for pricing" - never a good sign!
During my research, I did find this great article from Mother Earth News in 1979. Can't believe these systems are still seen as bleeding edge... And, btw, NO we're not building our own. Even if it only costs 160 bucks!
UPDATE: Please see the New Solar Incentives Post
[where: 10032] [where: Harlem] [where: Sugar Hill]
Apr 29, 2008
Solar Hot Water and Radiant Heating
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12 comments:
Hi there- I love your blog... would love to ask you some questions if you have a chance. michaeloreed@gmail.com
Thanks!
MR
I am an advocate of evacuated tubes and hope to use them soon. The design is quite pretty and althoigh I think it blows flat panel our of the water. There are issues with every system. The tubes need to be 2-3 feet off the roof to deter snow burying them. They can overheat and you need a heat dump of they will self destruct. In that sense the systems I have seen are way under sized to deter any risk. I am looking to haet my house with them and have heard of 130 tube systems working as residential heaters.
Access is important for these systems since the tubes can be damaged, but easily replaced.
Chinese tubes I have seen are thin walled and have no fluid heat transfer, but rely on direct conduction by metal fins. Very Cheap.
One last note. If you plan to be an active participant in the workings of your solar house, these are great. If you want to be a passive joe and use solar without the homework, stay flat panel.
Your blog re: solar hot water with these evacuated tubes interested me greatly and motivated me to do some research. After reviewing the two websites for the solar tube companies you mentioned, I contacted the manufacturer of the hot water tanks listed on Thermomax's website (800 582-8423). The gentleman I spoke with said that he knows a professor near him conducting a comparison study of the the evacuated tubes and that the efficiency of these solar tubes was not much different than the flat panels (given the improved technologies with the new flat panels) -- yet the cost was much greater for the evacuated and they were much more breakable. Also, snow does not melt on them since the evacuated tubes do not get hot which would render them useless (if covered with snow). He recommended reading a book called "Solar Water Heating" by Ramlow for more details. I was disappointed by this news, as I thought these evacuated tubes sounded like a massive improvement. Nonetheless, the technology does sound exciting in the face of $4 a gallon oil.
Thanks all for the comments. There seems to be a fair amount of controversy between flat-panel and evacuated tube solar water heating.
With the house's size and cold climate location (New York), I believe we would best utilize the system in a "Home heating" configuration - with the collector at a steeper angle to be most efficient in the winter (and less so in summer). I need to get some experts involved, but am hopeful that will remediate the over-heating issue.
As for the snow issue, yes that could be problematic. I've been reading about installations in Colorado (snow aplenty!) and looks like angle of install is key.
**I am interested to hear any pricing info you received from Thermomax.
I work for an HVAC company and I found your post very interesting.
Green in Harlem I am looking for places that are green in Harlem to show and tell on my tour A Taste of Harlem Food and Cultural tour. I am planning a green tour in June and I am putting together all of the components. I would love to know more about about your home and how green you have converted it. I can be reached at info@tasteharlem.com. Thanks, Jackie
I am really enjoying your blog. We own a new-construction townhouse in Harlem which is anything but green, and I have been looking into retrofitting options. Unfortunately, we get less sunlight than most townhouses because we are not on a brownstone block -- we immediately abut taller buildings to the east and are very close to taller buildings to the south (they have virtually no rear yard and thus almost reach our property line). I am considering a rooftop wind turbine, but if you wouldn't mind sharing your thoughts on how to evaluate the feasibility of solar I would appreciate hearing from you (elizabethbstein@gmail.com). Thanks in any case for such an awesomely interesting blog.
Uptown mom, solar is great, but you really do have to have good eastern and/or souther exposure. We installed solar on a house in Long Island and found the LIPA Solar Pioneer program helpful -http://www.lipower.org/efficiency/solar.started.html
as well as solar contractors for Long Island from - http://www.lishines.org/contractorselector.php.
The best thing you can do is ask solar contractors to come to your place and give you quotes and feedback as to you what will work best for your situation. This along with your existing research online should help your decision process.
Best luck
Uptown Mom: a couple of additional points.
- you might want to take a look at My Watts Estimator http://www.chooserenewables.com/estimator_start.php
- and, if you don't get a ton of direct sun all day long, it may be tough to generate enough electricity or hot water (although Solar hot water with evacuated tube collectors is so efficient, it may work). Best bet is get a few expert folks out there to see. We're happy to help with names.
Other things you can do instead is a gas-fired, on-demand water heater. The energy that goes into heating and then *storing* hot water is staggering.
Hi,
Solar hot water is a great technology. Have you taken a look at the new tankless water heaters? Actually you can lower your energy consumption by 35% and it's good for the environment. Please feel free to email me for more information on tankless water heaters.
Thanks!
Terri
Terri: happy to chat, but you left no email address...
Can you let me know how to get the solar panals or who did you use to install and the cost for the brownstone. My e-mail is jackie@tasteharlem.com
Thanks
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