Off Grid Home Forums Technical Discussion Passive Solar or Active Solar better for your home?

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    All solar systems use the sun but they do it in different ways. Some may be used to provide heat for a home, others can provide a constant source of hot water. Still other systems can generate power so that a homeowner can reduce their energy bill and even go off-grid in some cases. One thing that surprises many people is that these systems can be used in areas where sunlight is weak or intermittent. The key is to choosing a system that will work for your needs and the environment you live in.

    Active Solar Power

    These systems use solar panels to generate power or to heat water. They do require the installation of special panels and can be expensive in the beginning. Over time, the reduced costs that you will pay to heat or power your home will help defray the cost of the system. Because they use panels to actively harness solar energy, these systems are not dependent on the orientation of a home or the construction materials made to build that home.

    Passive Solar Power

    Passive solar systems rely on home orientation. This is the direction that a home faces. With passive solar systems, a home generally needs a southern orientation in order to take full advantage of sunlight in an area. Windows are positioned in the home in such a way that they let in the maximum amount of light and heat. Using windows and doors that are designed to prevent heat from escaping will mean that the home can be kept quite warm and that heating and lighting bills can be reduced.

    Before deciding which system you want to install, you should consider what you want to use solar power to do. If you want to heat your home and it is positioned properly, you may find that a passive system will work best. If power generation is your goal or you have a home that does not have a southern orientation you may find that you will need to look at active solar power systems rather than passive systems.


    Our roof is at a 45* angle to south and has limited room. Our calculations showed that we needed 11 75 watt panels in a seasonally adjustable fixed mounting, or 8 panels with a full tracking array. We did not have the room to mount the panels on the roof, so went with the 40% more efficient full tracking array.

    So, initially it cost an extra 2,500 to mount, over the cost of seasonally adjustable fixed mounts. The 3 less panels saved 1,200, for a net extra cost of 1,300 for a 100Ah/day @ 24VDC system. Our minimum winter sun was affected by a mountain on one side and trees on the other.

    Bringing in grid power would have cost 5,000 and our monthly bill would have been 100, so our 9,300 self installed full tracking system paid for itself in 43 months (9,300-5,000=4,300/100=43mos.) It must be noted that, installed by someone else, it would have been 17,100 (on bid), so then would have taken 121 months to pay for itself.

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