Factors to consider before expanding off grid solar systems

Increased Energy Consumption 

Sometimes energy needs change over time, and you need to expand your system to keep up. Adding  on your existing solar system by buying additional solar panels, inverters, or a battery bank expansion. 

Current solar panels aren’t harvesting enough. If your panels aren’t putting as much energy as you thought they would, the concern might not be about the size of your system. Other variables could be to reason for lower energy output: poor set up, temperature, shade, and the direction your panels are facing. 

Mounting direction & angle. If you live in the Northern Hemisphere, your panels should face true south. Facing panels directly into the sun during peak hours will optimize the energy  generated. You can’t exactly change the orientation of the roof on a house you already live in. Many have to settle for placement that’s a split between east and west. In this scenario, adding more panels is more cost-effective than trying to find the perfect orientation with your existing system. For a fixed tilt angle, your array should  be tilted at an angle approximately equal to your latitude. . If you use an adjustable pole mount, you can tilt to a steeper angle in the winter to optimize production throughout the year.

Temperature & location. Solar panels are rated at standard test conditions (STC). The tests are run in a controlled environment, with temperatures regulated to 77°F and an ideal amount of light shining down on the panels. In reality, living environment rarely matches these optimal conditions. Most panels harvest  about 10% less power than their rating due to heat, clouds, and other factors. A 300W panel might only put out around 270W on an average day. The maximum output is rarely achieved, except during clear sunny days with ideal conditions. There is another rating system called PTC,  that accounts for real-world conditions. PTC ratings  give  more accuracy   of how panels will perform. Before you size a system, take your local climate into account. Extreme climates translate into a larger knock on the rated efficiency of your system. 

Shade. Panel production is influenced by shade. Just several small shadows make a big impact on output. Solar panels need to be installed in full sunlight for optimal performance. Some modern panels including bypass diodes and half cut cells that assists with shading. If you have lower output, ensure the array isn’t shaded throughout the day. Also, ensure that your panels are clean from leaves and other debris. Over time this can build up and reduce performance.  

Aging equipment: Solar equipment  drop in efficiency when it starts to age. Solar panels last 30+ years, but the output decreases slightly yearly. Most panels are guaranteed to make 80% of their rated power after 25 years. After 5-10 years, production may dip under your energy needs. But if you didn’t take this into account, it isn’t too difficult to add parts to compensate for expected efficiency losses over the life of the system.
 

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