Network connections are required to send data from the acquisition system to the Internet. The Internet connection can be made wirelessly via a cell or satellite modem, or using a hard-wired connection, such as cable, DSL, or fiber-optic lines. The monitoring system’s data logger or gateway is connected to the router (and on to the Internet).
Data display options include local displays or Web portals. Local monitoring on an inverter or remote tabletop or wall-mounted display usually includes array and grid voltage, current, cumulative energy, and power.
A Web portal is the viewing platform for the PV system data, displayed via a computer, smartphone, or tablet. Multiple portals may be available for one PV system, with one a publicly available version offering a few details, and another (password-protected) providing enough information for maintenance and troubleshooting. Web portals can be branded with logos, and customized with site-specific information such as amount of carbon dioxide offset or the dollar value of energy generated. Reports on historic system production (for days, months, or years) can be created and downloaded from a Web portal as well.
Communications for monitoring can be entirely wireless, or rely on hardwired network cables (like CAT5 or CAT5E Ethernet cables) to move data from the inverter to the data logger or gateway, and on to the Internet via a router. Data from individual inverters can be transmitted over power lines (power-line communications; PLCs); Bluetooth; hard-wired Ethernet cables; or wirelessly.
Power supplies, like AC wall cubes, may be needed for an external data logger/gateway, cellular modem and energy meters. Per the National Electrical Code, the inverter AC output circuit must be dedicated to the PV system and cannot provide this 120 VAC power source.
The data hosted by Web portals varies slightly by system topology (i.e. MLPEs vs. string inverters) and by equipment manufacturer, but the data displayed by monitoring portals is very similar across different platforms. For a string inverter system, at minimum, the portal displays kilowatt-hours of production for each inverter on a daily, weekly, monthly, yearly, and lifetime basis. Inverter power, reported at 15-minute or hourly intervals; DC and AC voltage; and current are also commonly measured parameters. The portal will also indicate if there is a potential problem with an individual inverter, for example, if the data is not being transmitted, or the power or energy levels are outside normal thresholds.
For MLPE systems, data provided by a manufacturer’s portal is more in-depth, as the module-mounted electronics allow easy access to each PV module’s power (current and voltage) and energy data, plus historical system energy data (daily, weekly, monthly, yearly, and cumulative kilowatt-hours). Portals can indicate module-level failures or performance issues, and graphically represent a “bird’s eye view” physical layout.