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Net metered solar electric systems are the most cost effective alternative energy systems available to property owners today. Let's look at the other available technologies and see why this is...

Wind Generators

Wind generation is popular in the US today. For small systems, 10 kilowatts or less, suitable for residential, farm, and small business use the investment is similar to photovoltaic systems of similar ratings.

One of the most attractive features of wind generation is you can see the blades turning and in that way know its making power.

But that isn't necessarily true. For a small scale wind system to make appreciable power you need constant winds blowing at something like 15 mph. So even though the blades may be turning the generator may not be making much in the way of usable power.

Because of turbulence problems a properly sited wind generator should be place at least 30' higher than any obstruction (buildings, trees, hills) within 300' of the turbine. This greatly limits available locations as we may be talking about having the wind machine up over 100' off the ground. Towers to support these machines can be very costly and, if guyed, will take up a lot of real estate.

Wind generators require annual maintenance and that means climbing a tower or lowering the machine to the ground. Neither of these activities lends itself to the do-it-yourselfer. This annual cost quickly reduces the value of the investment.

Ice and bird strikes are another concern. Unbalanced blades can quickly rip a wind machine apart and bird strikes are considered by many to be poor stewardship of the land and environment. Bird watching is the fastest growing recreational activity in Wisconsin. With this growing popularity comes a growing and more vocal concern about bird kills from wind machines.

Geothermal Heat Pumps

One of the great innovations in alternative energy has been the recent availability of using the earth's heat to help offset energy usage. By pulling heat out of the ground you start the property's heating process at a much higher temperature than the outside air temperature, as much as 70 degrees in some cases.

Loops of plastic type pipe are either buried in the ground or placed down deep wells. A non-freezing fluid is pumped through the pipes and the heat that is picked up is used as a starting point for the building's heating system.

Geothermal heating has a definite place in Wisconsin but comes with a dirty little secret - the pumps use a lot of electricity. A lot. We have spoken with many home owners who have installed geothermal heat systems and this is almost always the first or second comment they share with us. While these systems reduce their natural or propane gas use they noticeably raise their electric costs.

Solar Hot Water (solar thermal)

This one compares very favorably with photovoltaics. In fact, solar thermal can pay back more quickly in some cases. The down sides are; annual maintenance costs and having large and heavy collectors on a roof.

These systems use an anti-freeze mix to circulate and collect the heat from the roof-mounted collector boxes. This fluid is typically non-toxic (you can find it in ice cream) but has one Achilles' heel: It breaks down and becomes an acid when exposed to high heat - during the summer, for example. The result of this is it needs to be changed every year and replaced with new fresh fluid. This is an ongoing cost for the life of the system.

The second problem is the large and heavy collectors. Remember, they're filled with fluid, on your roof. To support these requires strong mounting systems that must have bolts or other fasteners penetrate your roof. Additionally, the pipes that carry the fluid to and from the collectors also require roof penetrations. As a roofing company in business for 25 years, Kulp's knows that the fewer roof penetrations, the less chance there is for leaks.

See this link for information on how Kulp's Dawn-based solar thermal systems address these concerns.

Net Metered Solar Electric

Net metered solar is the hands down winner when it comes to energy production and value. By moving all of the generated power directly to the power company grid these systems can realize efficiencies of greater than 97%. That is, for every 100 watts of power collected 97 watts are delivered as immediately usable power. Battery based systems average less than 80% efficient.

And these systems are simple. The PV panels collect sunshine and turn it into direct current, DC, electrical power. This DC power is delivered to an electronic device, known as an inverter, which converts the DC into the alternating current (AC) we use in our homes and businesses. There are no moving parts. There are no components that require maintenance. There are no switches or controls the owner needs to monitor or flip in order for the system to work. Install in, file the required regulatory paperwork, turn the system on and you are making power.

Net metered solar electric systems basically come in two varieties; crystalline and thin-film.

Crystalline Solar Photo Voltaic

These are the solar electric panels we are all most familiar with. A glass-front rectangular panel with a deep blue or nearly black material just under the glass. These are typically placed just a few inches above the roof on aluminum frames.

These systems are very common. You see them on traffic signs. You see them on billboards. You see them on small boxes along side the highway. You also see them on homes.

The great advantage to these framed PV panels is their portability - that is, their portability for the installer. Because these are self-contained modules they can be assembled like an erector kit and transported in a pickup truck or van. These are by far the most popular PV system from an installer's point of view.

But they have a few problems...

The first is wind load. Because the panels are hollow underneath they act like a lifting surface (think wing) when the wind blows past them. This requires a substantial supporting frame, called the rack, and that frame requires multiple roof penetrations to anchor it to the roof. In addition, this uplift works against the structural design of a typical roof. Roofs are meant to be pushed down on. Only a roof that has been specifically engineered to withstand uplift is meant to be pulled up on. Placing a racked crystalline PV system on a roof not designed to withstand uplift is asking for trouble.

Advocates of crystalline will be quick to say that crystalline is more efficient than the thin-film PV Kulp's offers. This is only true if you focus only on that one statistic. When looked at in whole, thin-film outperforms crystalline both in terms of annual ouput and cost.

Kulp's Thin-Film Solar

Kulp's solution is to integrate the PV system into the roof in a way that addresses the above mentioned concerns. Essentially, instead of putting an energy collecting system on your roof, we turn your roof into an energy collector.

View our Why Our Solar? page for a discussion of the Kulp's approach, it's benefits, and a discussion on what the term PV "efficiency" truly means to you.

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solar@kulpsolar.com