There are three primary methods to harness the power of the sun in our houses:

• passive strategies
• photo-voltaic panels
• solar thermal technology.

Passive Strategies:

Passive solar strategies aren't the technological wonders of the solar family, but they are time tested and proven. Passive solar strategies include building orientation, natural day-lighting and installing thermal masses.

Orienting your house to properly harness the sun is not a difficult strategy (unless you’ve already built your house!), but it is often overlooked in favor of orienting houses to the road. Orienting a home to capture southern sunlight is the key. Larger expanses of windows should be focused on southern facing walls. Unfortunately, the warm summer sun can lead to overheating in homes that take advantage of a southern exposure. This can be managed with a properly designed shading device that blocks the hot summer sun, while allowing the needed winter sun to heat the house.

Natural day-lighting is often forgotten as a viable strategy to light a home. During the day, nature has provided us with all the light we need, even inside our homes. Using skylights, solar light tubes, proper window orientation, light shelves and low walls can all help to bring light deep into interior spaces, reducing the need for artificial lighting during the day. In addition to the benefit of not needing to have the lights on, the quality and color of daylight is much better than most artificial lighting.

Solar masses inside our homes have become more popular as home owners and builders recognize the benefit. A solar mass is a thick wall or floor, typically masonry or concrete, that absorbs excess heat during the day and then dissipates the heat during the evening and night. A well designed and placed solar mass can mitigate the difference between day and night temperatures. During the summer, a thermal mass helps to reduce cooling needs and during the winter a solar mass will reduce heating needs.

Photo-voltaic panels:

Photovoltaics are the most visible and well-known solar energy technology. Photovoltaics work by absorbing the light energy (photons) of the sun into a matrix that responds by knocking electrons to higher energy levels, thereby creating free electrons. A current builds in each panel and when tied together in series can create large amount of electricity. An average panel can produce up to 200 watts of electricity at peak performance. One of the big detractors of photovoltaics is cost versus efficiency. This comparison usually leads to long payback periods of 10-20 years. Another knock against photovoltaics is the need for storage capacity to handle night time and overcast lighting.

For many years, the only viable option for solar photovoltaic technology at the consumer level was crystalline silicon based panels. These are the panels we typically see on homes. Often bulky, these panels require specialized installation and roof penetrations. Crystalline panels typically last about 25 years before performance begins to degrade significantly. Because of the space needed to install crystalline panels, it is often unreasonable and cost prohibitive to use the system for all the power needs of a household.

Newer technologies include thin film solar which is characterized by photo-reactive inks applied to plastic films. While the performance of most thin films falls far short of that of their crystalline cousins, the real benefit is in varied applications and ease of installation. Thin films allow for solar installations to be integrated into building designs. Some products are even being marketed to be installed by roofing and siding contractors, reducing the cost of installation.

Solar Thermal:

The residential version of solar thermal technology is commonly applied to make hot water. Solar hot water panels absorb the heat energy of the sun to heat a liquid which in turn helps heat the water used for either domestic hot water needs or in radiant flooring systems.

The technologies in each manufacturer’s product can differ, but the general strategy is to use an absorbent metal attached to a series of tubes. The heat is transferred to the liquid which is then run through a heat exchanging coil which transfers the heat to the water you are using in the home. Solar hot water technology is much more efficient than photo-voltaics and also cheaper. The average payback for a solar hot water installation is only 5-10 years while the life of most solar hot water installations is 20-30 years.

Conclusions:

As far as renewable options go for today's homes, solar energy provides an array of strategies that when used together, can greatly reduce the energy needed from non-renewable sources to power our homes. The up-front cost can be daunting when looking to use solar energy technologies, but with a strategy of reducing energy needs first through high efficiency appliance, lighting and HVAC equipment and then using passive strategies to harness the power of the sun, you can greatly reduce the size and therefore cost of your solar power installation.

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