Establishing a remote connection to a device allows users to program custom settings off-site. This is especially useful for systems that may need seasonal adjustments or need small adjustments to the custom settings for improved performance.
Remote Monitoring of Off-grid Systems
Douglas Grubbs | Morningstar Corporation
Telecommunications repeater station in Canada. Photo courtesy of Howell Mayhew Engineering.
Morningstar Corporation is developing remote monitoring and control solutions for off-grid solar PV systems. In contrast with grid-tied systems, remote monitoring for off-grid systems involves not only the energy production of the solar PV array, but the historic charge/discharge state of the battery as well.
Demand for remote monitoring and control in off grid renewable systems is being driven by the need to:
Reduce costs associated with remote site visits.
Receive quick notification and act to eliminate power interruptions at a site.
Program custom settings off-site
Update firmware remotely
Examples of remote off-grid systems that can benefit from remote monitoring include geological monitoring, mines, telecom, industrial automation and agriculture applications. Other, more accessible off-grid systems can also benefit if they remain unattended for long periods of time. This includes lighting, security, traffic monitoring, leisure (marine, cabins, RV’s), pumping systems and cellular towers. Moreover, some residential and municipal applications with on-site personnel can benefit, if an installer or someone who understands the system is not available. Lastly, many battery-based residential, battery backup, rural electrification (residences, schools, hospitals) and UPS systems that are temporarily unattended may warrant remote visibility into system metrics.
The most basic remote monitoring systems provide the user with real-time information such as Battery Voltage, Battery Charging State (Bulk, Absorption, Float, Night etc), Charge Current, Load Current, Ah’s and/or kWh, Load State (On/Off), Temperatures (Battery, Ambient, Heat Sink).
More advanced remote monitoring allows for viewing or downloading internally logged data of daily values (charge Ah’s, Load Ah’s, Max. Battery Voltage, Min Battery Voltage) and events (Minutes in Absorption, Float and Equalize, Faults and Alarms). The historic daily values provide much needed information about how the system has been performing.
Daily logged data of a remote off-grid system.
For example, if the daily Absorption charging minutes is very low and no Float charging minutes are recorded, this indicates that the batteries did not get completely charged that day. If such a trend continues over several days, this could indicate the need for a larger PV array; loads to be shut off; or remote backup generator startup.
Consider another example when a battery bank nears its end of life. The battery might reach a full state of charge during the day, but the daily low battery voltage might start getting unusually low. Of course, it is entirely possible that the daily loads have increased also. Checking the daily load Ah will indicate if the battery seems to be providing fewer Ah’s that it had previously. For some customers who have critical power needs the daily Ah’s and minimum daily battery voltage information will help evaluate the health of the battery and if it needs replacement.
More advanced monitoring solutions include real-time live data logging directly from the controller to a data log file. This can be recorded in much shorter intervals than once a day as long as the data logging remains connected to the controller(s). This detailed information throughout the day can give more insight about energy usage and production. In addition it is helpful to review detailed information for troubleshooting faults and alarms to see what was taking place when a particular fault occurred. For example, a load surge can cause a brief overcurrent condition which may be showing up in the daily log file. Many people want to see if this type of infrequent Fault or Alarm is a problem or not and continuous data logging can shed more light on something that may be showing up in the Daily log files.
There is a strong trend for solutions that offer MODBUS RTU and MODBUS over IP which is an open protocol standard being adopted by the SunSpec Alliance. Many 3rd party software solutions have been developed with remote serial communications or with Ethernet adapters. For many of these types of solutions if the connection is lost, data logging stops.
However, new Ethernet Adapters are being complemented with web monitoring services which do not require a continuous connection from a computer. By including internal memory, if the remote connection is ever lost, the adapter will automatically upload the missing data to the web server when it reconnects to the internet.
For customers who have many solar PV sites, these new Internet PV System monitoring solutions provide a multi-controller system status screen. This provides customers with the ability to see any potential issues with many sites at once at a quick glance.
In some cases monitoring may reveal information which will inspire a customer to intervene and control the system in some way. Certain faults may require a reset which can be implemented remotely. It is also possible to remotely control devices to shut off loads to help the battery recover from a low state of charge or disable charging if necessary.
Establishing a remote connection to a device allows users to program custom settings off-site. This is especially useful for systems that may need seasonal adjustments or need small adjustments to the custom settings for improved performance. Many people use Morningstar’s MSView software to program custom settings remotely.
Remote connections are also starting to be able to facilitate remote firmware updates to enable new product features, improve performance or fix problems discovered in the field. The need to better monitor, remotely program settings and update firmware were the impetus behind the development of the Ethernet MeterBus Converter (EMC-1).
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