Saturday, August 27, 2011

An Interesting Roof Integrated Solar Water Heating Collector for Picky HOAs

Just ran across this interesting collector design from Velux -- the people who do the very popular skylights.

The collector sits flat to the roof and looks exactly like a regular Velux skylight.  There are no visible plumbing connections.  They use the same flashing system on the collectors as they do on their skylights.

It seems like this look might be a lot more acceptable to a picky HOA?

The SRCC performance ratings are comparable to other good flat plate collectors.

Mixed skylights and solar collectors.
Seems like a good idea, and I don't see any reason there could not be a DIY one.

More details on the Velux site...


Tuesday, August 23, 2011

Taco Variable Seed Pump, PlugNPlay PV, PV and house value, More Refs

This is a catch-up on a few new content additions to the site:

Sean's Report on the Taco 009  VT Variable Speed, Integrated Controller Pump
Thanks to Sean for providing this report on using the new Taco pump that has a built in differential controller and uses variable speed to control flow rate.
The pump is intended for solar water heating systems -- it eliminates the need for a separate differential controller, simplifies wiring, and also offers the advantages of varying pump flow to match collection conditions.

Sean's Taco 009 VT
In a nutshell, the Taco 009 VT pump has been performing well -- All the details here...

Another Plug-N-Play Microinverter PV Setup
AC Unison has announced that they will be offering an easy to install PV system that incorporates a microinverter within each of the PV modules.

They do not provide a lot of detail on the installation, but the data sheet lists the nominal voltage as 240VAC 60 Hz -- so, I'm not sure how it integrates with the house power.  About installation, it says "The integrated AC design of AUO AC Unison modules means the system installers only need to deal with AC connections. This makes the system installation simpler and faster. It is estimated to reduce installation time and costs by ¼ or more."

About expansion, it says "Modules can be added to the existing system one-by-one in the future as budget for the homeowner increases."

They also describe a data logger/gateway device and an online monitoring service -- apparently similar to the Enphase systems.

I did not see any mention of price or availability.

More details from the AUO website...

Its still unclear to me to what extent the power utility and building code inspectors need to be involved in this kind of an installation.

The similar Clarian system...

PV and Home Values
This is an interesting study done by Berkeley Labs on how the sale price of your home might be effected if you install a PV system.    The increases reported are surprisingly large -- on the high end, they are greater on a dollars per watt basis than what my system cost to install.

I'm not at all sure I believe the numbers, but its nice to know that there might be some benefit when you sell your house to having a solar system.  It might also make it worthwhile to document how the system works and the resulting savings for potential buyers.

See the "Solar Homes Sell at Premium" link here for details...

Best Solar References and News
I cleaned up and added some new references to this page that lists some of the news sources and references that I find useful for keeping up on what's going on in the renewable energy world...

If you know of any other good ones, please let me know.


Wednesday, August 10, 2011

Low Energy and Unusual Ways to Keep Cool

Here are some low energy, low carbon, cheap, off the beaten path ways to keep cool in this hot summer...

The Sleep Genie:
This is an idea from the SunFrost website.  It basically builds a little cubby around your bed and limits the active cooling to the small area.  Links here...

This idea is equally useful in the winter to reduce heating energy!

Mother Earth News just put up an article on built in bedrooms that might fit with the Sleep Genie idea quite well.

Randy suggested some time back that you can make use of the thermal mass of a waterbed by sleeping either right on the bed water bladder or with just a thin layer between you and the bladder.  I suppose a clever person could work out a way to keep the bladder water cool by introducing new water.

Simple Shading From the Outside
Windows let in very large amounts of solar heat and and are responsible (on average) for nearly half of home heat gain.  There are lots of inexpensive ways to add shading to the outside of the house where it is much more effective.   Overhangs, solar screens, awnings, a trellis, outside rollup shades, trees or vines, shade sails, ...
Lots of ideas on external shading ...

The main thing is finding out where your heat gain is coming from and reducing it at the source.

While windows are the worst of the heat gain sources, walls that receive a lot of sun during the day can also transfer a lot of heat to the house -- especially if they are not well insulated.  Shading whole walls can greatly reduce this gain.

Reflective Roofs
In hot climates, reflective roofs reduce attic temperatures and heat gain from the attic to the living space.

Reflective roofs...

This may not be for everyone, but here is a quick and cheap way to get a white roof...

AC in the Attic 
The FSEC has found that AC units and/or distribution ducts located in the attic typically have large coolth losses to the attic space.  Often big gains can be made by taking steps to reduce leakage of cooled air into the attic and to insulated against heat loss to the attic from ducts and AC equipment.
If you can move this equipment out of the attic, better yet.

Taking steps like more attic ventilation, radiant barriers, and reflective roofing can keep the attic cooler and help to reduce the coolth loss to the attic space from AC ducts and equipment in the attic.
These are all simple, cheap DIY projects.

Night Ventilation
In climates that have hot days but cool nights, a strategy of ventilating heavily at night to pre-cool the house thermal mass for the coming hot day can be very effective and very inexpensive.
This is how we use this strategy to cool our house without AC...

More on effective ventilation for cooling...

Using the Basement Cool Air
Here is an Fran's great story on defeating the evil air conditioner with a ten dollar fan and a scheme to get cool basement air up through the house and out the top...

I've heard from several people who have been able to use this simple technique to good effect.

Got Ideas???
If you have any other ideas or simple, low energy techniques that have worked for you, lets hear about them.


Tuesday, August 9, 2011

Send in those project updates!!

About a year ago, Lonnie sent in a description and pictures for his very nice and very simple thermosyphon solar water heating system.
Lonnie's thermosyphon solar water heater
Yesterday, I got an email from Lonnie with an update on how things were going with the system and how interesting it is to still be getting questions and comments on the system from all over the world.  I put the details on Lonnie's update here...

Its really nice and useful to hear how things are going after the system has been up and running for a while.

Please Send In Updates on Your Projects

So, the point of this blog entry is to encourage people who have sent projects in to send in an update on how things have worked out.   Any information on performance, things that have worked well, things that have not worked well, any suggestions for improving the design, ...

If things have gone well with the project, its great for people who might want to build it to know that -- it makes it much more likely that others will  do the same project.

If things have not gone well, its important to know that as well so that others can avoid having the same problem.

Thanks -- Gary

Tuesday, August 2, 2011

A Large Thermosyphon Solar Water Heater System for a Hospital Laundry in Pakistan

Jo describes in detail the design and building of a large thermosyphon solar water heating system for a hospital in Pakistan.  

This is a great story about building a large solar water heating system using local materials and local labor.  Lots of detail on the construction, and on the Pakistani culture and outstanding scenery -- you could make a TV series out of this.

Two banks of collectors thermosyphon hot water to the tank just above
the collectors.
Jo provideds a detailed report in pdf form and also has a very interesting year long blog on building the system, living in Pakistan, and seeing the country -- all the details start here....

Lots more on DIY solar water heating systems...

A couple pictures:
System diagram

Building the collector mounts.

Jo's Arduino based temperature logging system.


Gary August 2, 2011
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