Definition
Distributed PV is generation installed close to the customer, on a roof, in a campus, or on a facade. The site uses the power first, and surplus may be exported. It complements central PV plants. With an energy storage system, it supports peak shaving and valley filling, demand-side response, and a lower demand charge. It is part of a smart grid and an energy microgrid.
Core Elements of Distributed Photovoltaics
Distributed PV systems include photovoltaic modules, inverters, grid connection cabinets, smart meters, and power quality monitoring, among others. Grid connection must meet power quality and safety protection requirements. Combined with energy storage systems, surplus electricity during the day can be stored for evening use, maximizing self-consumption. Power generation, electricity usage, and power quality are monitored through a cloud platform, and operation strategies are optimized based on load forecasting.
IoT in distributed PV
IoT monitors the plant, collects the data, and supports remote maintenance. Inverter, smart meter, and power-quality monitor readings go to the cloud platform over 4G or WiFi, so power, energy, and power quality can be watched as they happen. With an energy storage system, demand-side response, and peak shaving and valley filling, the operating rules can run without a person at the site. SimtoLink can connect the devices, collect the data, and integrate them through APIs.
Selection and Implementation Recommendations
When selecting, judge the roof or the site, the installed capacity, whether the connection is self-use or self-use with export, the storage sizing, and the payback. In operation, power quality, protection, and coordination with the grid still have to hold. With demand-charge management and peak shaving and valley filling, commercial and industrial PV plus storage keeps improving its return. SimtoLink can cover the IoT path from the devices to the platform.
Point of interconnection and the self-use boundary
Distributed photovoltaics are generating equipment installed on the user side, with the electricity they produce supplied to the local load first. Modules turn light into direct current. The inverter turns that into alternating current synchronized with the grid. The point of interconnection decides whether, for metering, this electricity counts as self-use or as export. Whether surplus may go onto the grid depends on connection capacity, the agreement, and whether reverse power is allowed. It is not automatic just because more modules were installed. Usable power also depends on orientation, tilt, shade, temperature, and the inverter limit. Nameplate capacity is an upper bound, not the power that will certainly be produced at noon.
The site has to carry the modules and the mounting. Shade during the main generating hours has to be acceptable, and the transformer and protection at the point of interconnection have to be able to accept this inverter. When reverse power must be blocked, the control target is that power at the point of interconnection is not negative, or does not exceed the allowed value. The measurement point must sit at the real point of interconnection, not only on the inverter's own output. When storage is added, separate charging from photovoltaic surplus and charging from the grid. Those two kinds of electricity mean different things in settlement. Monitoring needs at least three readings at once: generation, consumption, and the point of interconnection. Generation alone cannot say how much was used on site.
Estimating daily energy and the bill directly from installed capacity easily goes wrong. Soiling, string mismatch, and power limiting make output lower than the estimate, and the limit may come from the grid or from a reverse-power requirement. It does not mean the equipment has failed. An inverter showing that it is running only means it is working. It does not mean power quality and protection settings already meet the interconnection conditions. Treating a rooftop branch meter as the point of interconnection makes reverse-power control act on the wrong object. Modules with very different orientations still placed on one string let the weaker side hold the whole string back.
Cleaning only the modules near the walkway, and ignoring shade on the back rows, leaves a loss that is not always alarmed. A small consumption at night or while stopped, if it is not counted, overstates the self-use share. For a check, take the interconnection curve of one clear day and one cloudy day, compare inverter output and load, and see whether limiting happened and whether surplus was actually exported. Used with an energy storage system, charge and discharge must appear in the reading at the same point of interconnection. Operating strategy should then be aligned with the metering window of the demand charge. Otherwise a large amount of generation does not necessarily lower the capacity charge.
Keep cloudy days and power-limited days on file separately. Judging the whole plant by noon power on a clear day counts hours that are often held down by reverse-power blocking as if the equipment were simply normal. Also keep the direction of power at the point of interconnection. Otherwise it is impossible to tell a rise in local load from surplus that was forbidden to export.
The inverter's own cumulative generation cannot replace the meter at the point of interconnection. The difference between them may come from line loss, power limiting, or metering points that do not match. Explain that difference before discussing the self-use share. Otherwise a metering problem is treated as generating capability.