Tuesday, June 15, 2010

An Active Solar System

I volunteered to help a friend whose house
 was on the Green Built Tour this past weekend, which was sponsored
 The house in Embudo, New Mexico is owned by, designed by,
 and built by Rob Stout of Southwest Solar Design.

 Even though my focus in solar energy has always been in the passive side
 of things this house is a nice combination of both active and passive. 
For this post I want to concentrate on the active. In future posts
 I will look at other aspects of this beautiful and interesting home.
The photo above shows the hot water solar collectors on the roof
 which are used for radiant slab heating and domestic hot water.
The metal box between the ladder and the door is an on demand,
 propane gas hot water heater for back up domestic hot water.
Behind the door is the mechanical room where there is a tank
 for the domestic hot water with a heat exchanger. 
The heat from the fluid from the collectors is transfered to the water
 in the tank where it then goes to the kitchen and bathroom.

What makes this set up interesting are the reflectors 
you see on the top and bottom of the collector.
 This is an idea that Rob came up with
 and he figures they double the out put of hot water in these collectors.

The reflector surface is an aluminum panel covered by mylar 
and only the bottom panel is adjustable. 
The small photovoltaic panel you see between the collectors
 powers the pump that circulates the water and anti-freeze mixture.

Some of the panels are used for 
the radiant slab heating with no storage tank.
 The fluid is warmed by the sun in the collectors 
and pumped directly into the concrete slab. 
At night the slab radiates heat back into the room.

This fuzzy photo shows a closet in the house with the pipes
 running from the collector on the roof directly into the slab. 
The pump is powered by the PV cells on the roof 
and you can just barely see the bottom of the expansion tank
 at the top of the photo.

While we are at it I want to show the 315 kW
 photovoltaic system Rob put on an out building.
 Originally the panels charged a bank of batteries
 but when the batteries wore out Rob converted to a grid tied system.
 The panels provided 1/3 more electricity than is used 
and in New Mexico the utility pays for that surplus electricity.

I have highlighted some of the work of Rob Stout in 3 previous posts:
 An Active Solar System on 6/15; 
and his work was included in Door Handles And Latches on 6/24.