Monitoring Batteryless PV Systems: Page 3 of 5

Intermediate

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A monitoring system can help assess PV system performance in real time or over a duration of time, and provide on-site and remotely accessible information for system owners and installers, and the general public.
Batteryless PV monitoring systems provide Web portals for remote, online access to the system through a computer, smartphone, or tablet.
The Fronius Datamanager is a wireless data logger that comes preinstalled in new inverters, and can be retrofitted to older models.
Solectria’s SolrenView DAS Gateway can monitor up to 16 inverters and owners can opt to share data publicly.
While net-energy meters and PV production meters both look like the ubiquitous kWh meter, it’s their position in the system that defines what they are monitoring: A net meter is placed between the AC service entrance and the utility grid connection.
While net-energy meters and PV production meters both look like the ubiquitous kWh meter, it’s their position in the system that defines what they are monitoring: A PV production meter is positioned between the inverter and the AC service entrance connection.
PV system data can be displayed via a wireless tabletop unit, like the SMA America Sunny Beam.
A current transducer snaps closed around a wire to measure current via induction.
Data can be conveyed from the data logger to the display or network connection via dedicated cable, wirelessly (as shown), or over power lines.
Most monitoring systems display very similar data, albeit in different visual interfaces. The biggest difference is that MLPE systems, like this Enphase Enlighten display, allow monitoring of individual PV modules.
Schneider Electric’s Conext Monitor 20 can monitor data from up to three Conext RL inverters.
PV monitoring options offered by inverter manufacturers, such as Solectria’s SolrenView (above), offer similar features and customizable views.
The Enphase Envoy collects data via the power lines from Enphase microinverters; besides an AC power supply, no additional wiring is necessary.
The SolarEdge mobile app allows monitoring system performance from almost anywhere. Most portals also provide email alerts.
ABB’s Aurora Vision Web portal displays data from each microinverter. The eight inverters in this system appear as overlapping lines on the graph—each inverter’s production has been nearly identical for the week shown, indicating that the system is performing well.

Regardless of system type, reports on energy production history can be downloaded from the Web portal, and most portals can be configured to send emails if the system is offline or other errors occur. Web portal data is also available via smartphones and tablets. Most portals can report data collected from an optional revenue-grade energy meter as well as temperature and solar irradiance from an optional weather station. However, if a revenue-grade meter and/or weather station is a system requirement, double-check with the data system manufacturer to verify that the data can be captured and logged. If not, Web portals can access data from local public weather stations (see “Monitoring the Weather” sidebar).

String Inverter Systems

Fronius is one of the few residential inverter manufacturers that includes complete monitoring in the purchase price of the inverter. Fronius’s Galvo inverters (1.5 to 3.1 kW) have an integrated Datamanager 2 data logger to capture system information, which is relayed to its Web portal. The Datamanager uses WiFi to avoid cables and power supplies, although it can be connected to the router via network cable. The Datamanager includes a smartphone app for commissioning—just take a photo of the inverter’s barcode to set up online monitoring. Fronius IG-plus inverters can be retrofitted with the Datamanager 2 card, and the Fronius FE series can provide module-level monitoring with Tigo optimizers. The Fronius Personal Display unit can provide local monitoring of up to 15 inverters, and is available with or without data logging capabilities.

Kaco offers its watchDOG communication card; each can monitor three inverters. Installed inside the inverter, no external hardware is necessary except an Ethernet connection. The watchDOG transmits data to the Kaco Blueplanet Web portal, which is free for systems up to 10 kW (systems over 10 kW are charged $75 per year plus $1 per kW). Kaco’s M-series inverters have a preinstalled Energy Management Unit for use with Tigo MLPEs.

SMA America’s Webconnect Piggy-back card can collect and transmit data from up to four inverters to the free Sunny Portal website via a hardwired network connection. The card is installed inside the inverter, and uses a hardwired connection to the router—but could be connected by wireless adapter. SMA America also offers the Sunny Beam, a solar-powered tabletop display unit that communicates wirelessly via Bluetooth with up to 12 Sunny Boy HFUS inverters. Ninety days of data is stored in the Sunny Beam and can be transferred to a computer via a USB connection.

Solectria has an optional SolrenView DAS gateway for use with its PVI TL line of residential string inverters. One gateway can monitor up to 16 inverters. The hardwired gateway transmits data to the SolrenView Web portal via the household router. For systems under 10 kW, customized portal access is free for the life of system; owners can choose whether the portal is public or private.

Schneider Electric offers a similar data logger—the Conext Monitor 20 unit for up to three Conext RL residential inverters. Both Solectria and Schneider’s gateway devices require an external AC power source.

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