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Most Solar Panels Facing the Wrong Way, Experts Say


Solar PanelsAccording to a new study by the Pecan Street Research Institute, solar panels should point west instead of south, as previously believed.

It’s long been thought that pointing solar panels south (for locations in the Northern Hemisphere) will lead to best performance and energy output, but it turns out that pointing them west is more effective because peak demand on the power grid is in the afternoon and evening. Maximizing solar power during that period is more useful at reducing the need for sources of energy that pollute.

Experts at the Pecan Street Research Institute have found that the key to solar panel efficacy is not only how much electricity is produced but also when it is produced. West-facing solar panels produce 49% more electricity during peak demand time than their south-facing counterparts.

In Texas, as in most places in the US, peak demand times are 3 p.m. to 7 p.m., which also corresponds with the heat of the day. Peak demand time happens when people arrive home from work and begin turning on lights, using appliances, etc. This is the time of day power grids are most likely to become overloaded and when electricity is most expensive.

If clean electricity is produced from correctly-facing solar panels that are more effective, this will reduce the stress on the grid. Experts stress that incentives for solar panels should be aligned so that energy production follows peak demand – something that is not happening right now.

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  1. Given the angle of the sun,unobstructed west walls,with pv panel sheathing would actually give highest matched 3-7pm yeilds.At over 45* latitudes,south walls give the largest year round fixed array solar yeilds.How much of this peak consumption is air conditioning?That is a ghost load as its due too crappy buildings.

  2. That depends entirely on what you are doing with your photovoltaic power.  If you are charging batteries then you most certainly want to face South.  If you want the longest duration of nominal power generation, you want to face south.  Facing West cuts the duration of nominal power generation by 30%. That is allot of missing production.  If the value of your power changes over time and you are selling back to the grid at time of use rates, then it might be a good idea to face southwest, in order to produce power when it is most expensive.  
    Unfortunately, most homeowners don’t have the luxury of deciding exactly what direction the module will face as most home owners are installing on their fixed roof tops.  If anyone has the opportunity to pole mount their PV, they should most certainly consider a one or two axis tracker as you can extend the nominal power output by 25-35% depending on your latitude.

  3. I’m not sure this is accurate. I have equal size solar arrays, one facing South and one facing West. I consistently see better production from my South facing array. This graph of monthly production by array will demonstrate my point. http://www.sunnyportal.com/Templates/PublicPage.aspx?page=428071fa-dbf5-4ba3-aeeb-19a07b9db8ad


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