Site assessment or site survey is an important step in the system design and installation process. During the on-site assessment, the installer should collect all the necessary information required for system design, planning and optimization to improve the timeliness and safety of the installation. The goal of on-site assessment is to determine the location of the photovoltaic array, roof specifications, shading conditions, effective area, and other considerations.
①Position of photovoltaic array
In most urban areas, photovoltaic arrays are installed on the roof of buildings; in the case of large open ground (no trees or nearby buildings sheltered), ground-mounted systems may also be used. There are many options here, usually depending on roof inclination and orientation, or ground conditions.
② Active reminder of energy efficiency
In order for the grid-connected photovoltaic system to meet most or even all of the owners’ daily electrical energy needs, the designer should provide the system owner with a list of recommendations to reduce the owner’s energy use.
③Health, safety and environment (HSE) risks
There are several important risks associated with photovoltaic installations. These risks include working at heights, manual construction (lifting or moving heavy objects), and live working. The installer shall conduct a risk assessment for each site, and determine the specific risks of the site during the site assessment. They have to review the work before starting the installation.
Any local environmental characteristics that may affect equipment selection must be identified, including:
·Local temperature range: The device can only work within the specified temperature range, which will be given in the device data sheet. When designing a photovoltaic array, it is also important to understand the local temperature range.
·Salt spray weather and other corrosive conditions: When the photovoltaic system is to be exposed to the salt spray environment, such as within 1km from the coast, the photovoltaic modules that have passed the salt spray test should be selected, and the modules should pass IEC 61701 “Photovoltaic
(PV) module salt spray corrosion test” certification.
·Snowfall: In areas with heavy snow load, the installation of photovoltaic modules should withstand the downward pressure caused by the snow load accumulated on the surface of the photovoltaic modules. According to IEC 61215, the rated load capacity of photovoltaic modules can be selected as 5400Pa
⑤Installation position of system balance components
The location of other equipment on site must also be determined, including:
·Photovoltaic combiner box (if required).
·Inverter: The inverter should be placed in an easy-to-access place to prevent direct sunlight and good ventilation. The location of all equipment should be marked on the structural drawing or building drawing. If there is no such drawing, the on-site investigation personnel should prepare a sketch of the site. Digital camera records should be taken of the site and the recommended location of each device.
⑥ Site planning
Before installing the system, the installer needs to complete a detailed site plan, including the site’s buildings, sun shelters, roads, and physical layout, and the system involved needs to be drawn on the drawing. The site plan should include dimensions such as roof length, cable length, component location, and building spacing.