Passive Solar Power

I learned about passive solar power (no electrical or mechanical components) the year I graduated, when I chose it as my theme paper.  At that time, we were just learning about the power of the sun and how to put it to better use.  To add to my interest, there was quite an energy crisis going on.  Cars were in long lines to buy gas and it seemed everyone was adding more insulation, buying wood stoves and doing what they could to economize.

In the early 80’s we put up a new home ourselves, and didn’t go on the grid for about 6 months.  This was in central Texas, and we had 3 small children.  Remembering my high school studies, I purchased a children’s pool and spray painted it black, covering it with clear plastic.  In the morning I would fill that pool half-way up with water and by the time for the children’s bath after dinner, I needed to fill it the rest of the way with cool water to make a perfect bath, the water was that hot!  I emptied it in the morning into the garden and started it all again.  They still remember those garden baths.  I had other containers that I used to solar heat the dish water.

We made a solar cooker out of a cardboard box… that was OK, but still took forever to get anything done.  I remember doing quite a bit of food drying on screens which was quite acceptable in the dry Texas sun.  We made use of windows that opened at the top for cross breezes and thermal drapes to block out the harsh sun and let in the evening breeze.

About 5 years ago, I learned how far solar power has come when I hired a company to install solar panels to heat our pool and house’s hot water.  I had the pool re-covered in a beautiful black marsite, (reminiscent of the children’s bath so many years ago).  We swam many times in a bathwater temp of 100 degrees.   To make the best use of the solar heated water, we needed to take our showers in the late morning/early afternoon and run the dishwasher and hot clothes washing at that time as well.  This made the best use of optimal sunshine.

Sandy's solar heated black pool

At our small house, we have a solar powered fan for the greenhouse and use the sun to do the majority of heating of the hot tub.  We use passive solar power for drying our clothes (clothes line).  It would be nice to put up some solar cells for heating water here but truthfully, the investment takes so many years to re-coup that we would not be likely to ever see the break-even point in our life.  Hopefully the prices will come down.










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5 Comments on "Passive Solar Power"

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  1. Those are very good thoughts. We should all be using the sun more effectively. As for your hot water dilemma, how about working on a solar batch water heating system? There a nice three-part solar batch water heating video series here as well as many more solar energy videos. Perhaps they’ll help.

  2. Estar says:

    I don’t think solar cells are the best way to go for heating water. You were already on the right track with passive solar. Way back in the early 80s I visited a dentist with a solar hot water system in northeastern WA. It was working even on an overcast 30s winter day. “Panels” on the roof contained pipes with water to be heated by the sun. The pipes led to a big heat sink tank in the basement. The water in those pipes was not used for showers, etc. It was only used to heat the water in the big tank. Another circuit of pipes led from the heat sink tank into the hot water heater, and heated the water in there. The water in the hot water heater could also be heated with electric or gas if the weather was too cold to rely only on the sun.

  3. Sol says:

    Built a passive solar home 6 years back, in a Canada border state. 14% south facing glazing to home square footage, on a sunny day in December best guess is it adds 30 degress to the inside temp. Internal mass to absorb it is crucial, and insulation to not let it escape. Once phase change building materials (PCMs, BASF makes one called SmartBoard) become more affordable then there won’t be as much need for concrete and/or water for mass. Glazing selection is critical too, no low-e or reflective coatings that block the heat. We heat strictly with wood, and with the combination of the insulation value of ICF and the passive solar heat, we use less wood than a home half our size. Not sure what it would buy anyone down south, but with our 7 month long heating season up here, it works great.

  4. Mike Engel says:

    When I built my home, it only took 7 years!, I designed it to get direct sunlight in winter and it’s shaded in the summer, and packed in as much insulation as possible.
    My wife has RA so I have a theraputic pool with a handifcap lift, 20 by 40 by 5 feet deep all across she could walk laps in so I have a 16mil solar cover for it and the darkest liner I could get and it stays around 90 this time of year. I purchased a 72 feet long coil of stainless steel that I am going to place inside a plate steel box filled with sand to store heat, place it in the center of a firepit down hill from the pool, and pipe it into the pool near the top and near the bottom. When the block heats with the coil in it from the wood fire it will flow naturally and extend the swimming season and I can burn leaves and pine, not just Oak cause there is no flue. I am still looking for an old steel satelite dish to hing over the top to trap ashes, but I am a tree farmer and have an endless supply of pine nearby, especially since I need to take the time and get up there and reclear the mile and a half of roads I have. Gonna start clearing twice a month and haul home the trunks in long lengths so I can fit more than half a cord in the bed of my pickup and kill two birds with one project.

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