Solar panel mounting height refers to the vertical distance between the ground (or the mounting surface) and the lowest edge of the solar panels in a ground-mounted or elevated solar array. It's an important design consideration that can affect the performance, cost, and maintenance of a solar electric system, especially when using bifacial modules.
How Mounting Height Affects a Solar Electric System:
Energy Yield (Especially for Bifacial):
Albedo Effect (Bifacial): For bifacial solar panels, mounting height significantly influences the amount of albedo light (reflected sunlight) that reaches the back of the panels. A higher mounting height generally allows more reflected light to be captured, increasing energy yield. However, there are diminishing returns beyond a certain point, typically around 1 meter (3.3 feet) or more. The optimal height depends on factors like ground albedo, row spacing, and tilt angle.
Airflow and Cooling (All Panels): Increased height can improve airflow around and under the panels, helping to keep them cooler. Solar panels are less efficient at higher temperatures, so better cooling can lead to a slight increase in energy yield. However, in very windy locations, increased height could lead to higher wind loads, requiring stronger and more expensive mounting structures.
Shading:
Self-Shading: In systems with multiple rows of panels, a lower mounting height can increase the risk of self-shading, where one row of panels casts a shadow on the row behind it, especially during early morning and late afternoon hours.
Obstruction Shading: A higher mounting height can help to avoid shading from nearby vegetation, fences, or other obstacles, although it will not help with shading from taller objects that are further away, such as trees and buildings.
Installation and Maintenance Costs:
Higher Costs: Higher mounting heights generally require more substantial and expensive mounting structures to withstand wind loads and maintain stability. This can increase the upfront capital cost of the system.
Increased Labor: Installing and working on panels at greater heights can be more challenging and time-consuming for installers and maintenance crews, potentially increasing labor costs.
Specialized Equipment: Higher installations may require specialized equipment like lifts or scaffolding, adding to the overall cost.
Land Use and Aesthetics:
Visual Impact: Higher mounting heights can have a more significant visual impact on the surrounding landscape.
Land Use Underneath: Elevated mounting can allow for dual use of the land beneath the panels. For example, grazing for small livestock, pollinator habitats, or certain types of agriculture may be possible with sufficient clearance.
Safety:
Wind Loads: Higher mounting heights expose panels to stronger wind loads, increasing the risk of damage if the structures are not adequately engineered.
Worker Safety: Working at heights requires adherence to strict safety protocols to prevent falls and other accidents.
Optimal Mounting Height:
There's no single "best" mounting height for all solar systems. The optimal height depends on a variety of factors, including:
Type of Panels: Bifacial panels benefit more from increased height than monofacial panels.
Ground Albedo: Higher albedo surfaces call for greater consideration of the mounting height for bifacial systems.
Climate: Wind loads, snowfall, and temperature all play a role.
System Design: Row spacing, tilt angle, and tracking systems (if used) influence the optimal height.
Project Goals: Maximizing energy yield, minimizing cost, dual land use, and aesthetics all need to be considered.
Local Regulations: Building codes and permitting requirements may dictate minimum or maximum heights.
Typical Mounting Heights:
Residential Ground Mounts: Often 0.5 - 1.5 meters (1.6 - 5 feet)
Commercial and Utility-Scale: Can range from 0.5 meters to over 3 meters (1.6 - 10+ feet), especially for systems using trackers or designed for dual land use.
Carports: Typically have a clearance height of at least 2.5 - 3 meters, and often much higher, which is ideal for bifacial modules.
In Conclusion:
Solar panel mounting height is a multifaceted design consideration that impacts energy yield, cost, maintenance, and land use. While higher mounting can enhance the performance of bifacial panels and improve cooling, it also increases structural requirements and costs. Finding the optimal mounting height involves carefully balancing these factors based on the specific project goals, site conditions, and local regulations. For most ground-mounted systems, a mounting height of 0.5 to 1.5 meters is a good starting point, but further analysis is often necessary to determine the most effective and economical solution.