Solar in the High Country
Since 1992 Innovative Energy has designed, installed and serviced hundreds of renewable energy (RE) systems. Most of these systems have involved the use of PV. As a result, we have a very good understanding of what is required to make a PV system work optimally in our area. The reduced atmospheric density, precipitation, ice dynamics and lower temperatures are the primary factors that affect PV design and installation at an elevation of 9600 feet.
Most PV modules are rated at standard test conditions (STC). The STC ratings are based on sea level air density and temperatures that are different from what we see and because of this, we typically exceed STC values. If you were to compare the production of two identical PV systems, one in Summit County and one in the southwestern US, the PV system in Summit County would have higher instantaneous power readings. Basically, a photovoltaic panel is really an electronic device that generates electricity from sun light, not heat. This makes our high country region ideal for solar.
There are extra considerations when designing PV systems in our region. In fact, we have repaired systems designed and installed incorrectly that have failed because these considerations were not taken seriously.
The ice and snow that forms on a roof will also form on PV modules, It is imperative that any PV module selected for use in the high country be rated at a minimum of 113 pounds per square foot of snow loading, however, roof or array tilt may decrease the need for such a high snow load in some cases. Not all modules meet this requirement so we are careful when choosing panels for local installations.
The single most important factor with regard to PV performance is solar access. Shading will dramatically decrease the PV production. Snow that covers panels will act as shade and any design in areas of heavy winter snowfall should take this into account. We keep clear of roof valleys and roof pitch changes. The valleys and pitch breaks hold the snow and can experience freeze/thaw cycles and flow like a glacier; we have seen this effect break PV modules.
One other issue that should be of concern is how snow and ice sheets off of the PV modules. The asphalt shingle low angle roof would normally hold snow and ice. However, if PV modules are installed, there will be a time when the ice clears and it will happen all at once. So unless the system is designed properly, public safety may be an issue. For this and other reasons, it is best to select a roof area that will shed snow best. Remember, if snow fencing is required on a roof with solar panels, the snow may build up above the snow fence, covering the panels and reducing the ability of the panels to shed snow. This creates a significant reduction in system production throughout the winter.
In many cases, solar power can be more efficient than wind power in these higher elevations. The lower temperatures and higher insolation allows PV systems to produce more power than predicted at standard testing conditions. On the other hand, wind turbines perform best in consistent wind speeds which can be difficult to find in our often turbulent and gusty wind environment. In the high country, we see both lower atmospheric density (less power to push the blades of the turbine) and turbulent, shifty winds that not only decrease efficiency, but also create excessive wear and tear on the turbine.
Determining a good wind site can be difficult to do. If you have a relatively open solar window in this area we can very accurately predict the power production of a PV system. Properly analysing a good wind site requires the installation of a wind measuring device and the collection of a few months of data. Read more on wind site feasibility below under our Wind Power tab.
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