
Going Solar - Energy from the Sun

We will find out in lesson 2 that the sun is the source of nearly all our energy (nearly all of the renewable energy and the chemical energy in the fossil fuels). In the winter, we crave the warm rays, and in the summer, we may hide from the sun and its oppressive heat. For most of us in America, we could obtain all our home energy needs directly from the sun year-round but it would require a quality house that was well designed and placed. For the rest of us, however, some of these solar options are a good way of reducing the heating, lighting, and cooling bills. Here, passive solar heating options are discussed. Passive means that no external energy is used. It is, in essence, good design (no pumps, no electrical energy).
Face the house towards the south (in the N. hemisphere) to maximize the exposure to the sun. Unfortunately, most of our homes are situated so they face the roadway regardless of the orientation towards the sun. Nor can we physically move our houses very easily, but keep these things in mind when you build your 4,000 square foot palace. Natural lighting reduces your electricity bill and reduces your pollution footprint. Most of us are interested in capturing the sunlight so we can live in bright locations. (Without sunlight, you can become depressed and lose out on vitamin D. Submariners, for example, have UV lamps so they can get a bit of a tan and avoid becoming "SAD" seasonal affective disorder). If you live in a very hot location, you might consider doing the opposite to prevent the solar energy from entering your house.
You need windows, of course, to let the light in. Have large windows at the front of the house (facing south) and smaller windows on the north side of the house. The traditional problem with windows has been that they let light in but also let heat out. The old window is both an energy source (in a sense) and an energy drain.

shade for the house during the summer months
but will let more light into the windows during
the fall and winter when the leaves are no longer
on the trees.
With modern windows, the insulation properties have dramatically increased with improvements and new materials, surface coatings to reflect certain wavelengths of light, and double or triple glazing with halogen molecules such as Xenon in between the panes. With all these changes, the window can be an energy source for the home rather than an energy drain. The materials and xenon are, however, expensive, so these windows do not come cheap.
You can plant trees that shed their leaves (those would be deciduous trees) and can also have overhangs on your house to limit the sunlight entering the house during the summer months when the sun appears to cross the sky at a higher angle. Once the (solar) energy is in the house, it needs to be stored. Even in desert locations, the day may be scalding, but the nights can be very cold. Our passive solar house needs a thermal mass to absorb the energy and radiate it back to the house during the night. Brick chimneys, brick walls, and adobe floors are often used. The house will need to have good insulation, also, to prevent the heat from escaping in the cool evening and nighttime hours or get in during the heat of the day. Heavy insulating drapes and airlock type doors can help prevent heat loss. Air leaks are also a significant source of heat losses/gains in many older houses.

I am not 21 feet tall. But this image does help explain why we think the sun is hotter during the hours of 12 to 1 in the afternoon. If the same picture were taken then, the shadow would be much smaller (okay, small bulge where my waistline is losing the battle of the bulge!) The sun is more or less directly overhead at noon and the same rays are concentrated over a smaller area. In the early morning, the same rays fall over a larger area (hence my 21-foot long shadow); they are less concentrated. The sun does not know what time it is and so does not become hotter or colder on our time schedule! If I took the picture in the winter at the same time, my shadow would be longer still.

Solar Panels
We will cover photovoltaic cells in the renewable electricity generation pages (lesson 03) where we cover generation at the utility scale. You can also add solar panels to your roof or to a community solar project (a collection of panels where you own the panels but that are clustered together away from your residence but still locally placed). By adding solar cells, you reduce your electricity consumption from the grid and are using a cleaner energy source.
