Solar photovoltaic (PV)

Solar photovoltaic (PV) systems generate electricity from sunlight, reducing the building’s reliance on grid electricity. PV systems can also be paired with battery energy storage systems (BESS) to maximize savings.

How solar PV systems work

Solar photovoltaic (PV) technology converts sunlight directly into electricity using the photovoltaic effect.

1. Absorption: The process begins when photons (particles of light) from the sun strike a solar panel, which is composed of many solar cells.
2. Conversion: Solar cells are made of semiconductor materials, typically silicon, treated to create an electric field (like the positive and negative terminals of a battery). When a photon is absorbed by the silicon, it excites and dislodges an electron from the silicon atoms.
3. Current Generation: The internal electric field in the cell forces the dislodged, negatively charged electrons to move in a particular direction, creating an electric current. This current is known as Direct Current (DC).
4. Inversion: Since most homes and the utility grid use Alternating Current (AC), a key component called an inverter converts the DC electricity generated by the panels into usable AC electricity.
5. Distribution: The AC electricity then flows to the building's electrical panel for use or is sent back to the utility grid.

Design parameters

The overall performance and efficiency of a solar PV system depend on optimizing several key parameters, both for the individual panel and the overall system design.

Parameter	Description	Optimization Goal
Orientation (Azimuth)	The compass direction the panels face.	Due South (in the Northern Hemisphere) or Due North (in the Southern Hemisphere) to maximize annual sun exposure.
Tilt Angle	The angle of the panel relative to the horizontal.	Typically set equal to the site's latitude for maximum annual production, or slightly steeper for winter-peaked demand.
Shading Analysis	Assessing shadows from trees, chimneys, or adjacent buildings.	The system must be designed to minimize shading at all times of the day, as even partial shading can significantly reduce the output of an entire string of panels.
System Sizing	Determining the total capacity (in kilowatts-peak) of the array.	Sized based on the client's energy consumption (kWh/year), available roof/land space, and the specific solar irradiance data for the location.
Inverter Selection	Choosing between string inverters (central unit) or microinverters (one per panel).	Microinverters are often chosen when shading is a concern, as they allow each panel to operate independently.

PV tilt angle

While the latitude-based angle is a good general guideline, seasonal adjustments can further optimize energy production. The sun's position in the sky changes with the seasons, so adjusting the tilt angle accordingly can help capture more sunlight during different times of the year.

• Winter: During the winter months, the sun is lower in the sky. Increasing the tilt angle by about 15° more than your latitude can help maximize exposure. For example, if your latitude is 30°, a winter tilt angle of 45° may be more effective.
• Summer: In the summer, the sun is higher in the sky. Decreasing the tilt angle by about 15° less than your latitude can help capture more direct sunlight. So, a summer tilt angle of 15° for a location at 30° latitude can be beneficial.

Adjustable Mounting Systems

For those who want to maximize their system's efficiency throughout the year, adjustable mounting systems are available. These systems allow you to change the tilt angle of your solar panels manually or automatically to match the optimal seasonal angles. Although adjustable systems can increase the initial cost of the installation, they can significantly boost energy production and reduce payback time.