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The Effect of Shade on a Solar Array

Solar Basics | 2 min read

When considering a location for a solar array, one of the most important factors to think about is shade. Since direct sunlight is required for a solar panel to produce electricity, shade is the enemy of production.


My roof gets shade all day long. Is it a good location for a solar array?

It is difficult to calculate the effects of shade from a tree or other obstructions by looking periodically at your roof to see if it is getting direct sunlight.  Fortunately, at Paradise Energy Solutions we use a tool called a Solar Pathfinder, which gives us an immediate picture of every hour of every month of the year, to see exactly when shade will fall on the array.


Even if it appears that a specific location is in the sun all day long, it is possible that the pathfinder will reveal shade in the early morning or late afternoon, or in the wintertime when the sun is lower in the sky.  A proper Solar Pathfinder analysis will indicate the percentage of production lost due to shade, which we then take into consideration for our performance guarantee.





Do utility wires and tree branches affect my array?

Yes.  Utility wires and trees (even without leaves in the wintertime) may adversely affect the production of the array depending on what time of they day they cast shade on the array.  Even if it is only partially shading a panel, it could completely eliminate the power production from that panel, since the cells in a panel are connected together.





Is there any way that I can calculate shade myself?

If you want to get a rough estimate of shade before you have a Solar Consultant from Paradise Energy Solutions visit your location, you can use the 1-3 rule.  If you have a tree that is 20 feet taller than the array, you would want your array to be at least 60 feet (3 x 20') from the tree to avoid significant shade.  Remember, this is only a rough analysis of shading. An onsite shade analysis from one of our Solar Consultants is required for us to give a good estimate of production.


Will shade effect my system payback period?

Since electricity production from the solar array provides the revenue stream to pay off the array, shade will affect your system payback period.  If you array experiences 30% shade, for example, your payback period will be lengthened proportionally.





Does Paradise Energy guarantee the output of my solar array?

Yes.  Paradise Energy Solutions guarantees the output of new arrays for 10 years.  In fact, if the array does not produce as guaranteed, PES will reimburse the customer for the lost production times their initial price per kWh!  As expected, this guarantee will require a proper shade analysis.  Consult with your Solar Consultant to find out if your contract includes a guaranteed production amount or an estimated production amount.  If it is estimated, it may require a more extensive shade analysis from one of our Project Managers to guarantee production.


Learn more about what goes into a PV Solar system design here.


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