Renovation of 37 Combiner Boxes at the Jiaxing Old Power Station

Recently, the renovation project of 37 combiner boxes at the Jiaxing old power station, undertaken by Fonrich New Energy, was successfully completed. The renovation plan designed and installed by Fonrich, along with its high-quality products and services, has been highly recognized by the owner.

Preliminary On-Site Survey

   Fonrich engineers conducted a detailed and thorough preliminary investigation of the renovation project. This project involved a small number of rooftop combiner boxes that were scattered. If traditional wired communication methods were used, the following issues might arise:

1. Affecting the aesthetics of the building；

2. Due to site factors, a large number of 485 cables would be needed, impacting the project’s economic efficiency；

3. The communication distance between rooftops is short, with many obstruction factors due to height differences, potentially leading to non-standard wiring and affecting communication quality.

Based on these factors, the engineers recommended a wireless communication solution to the client. The renovation project of the 37 combiner boxes was distributed across three areas. We selected one area (15 units) for a detailed introduction to let everyone understand the detailed process and related details of the old power station renovation.

Specific Renovation Details

For the wireless communication engineering application case, in the selection of antenna brackets, engineers comprehensively considered aspects such as corrosion resistance, high-temperature resistance, and ease of use, choosing PVC pipes (diameter 2.0cm, length 75cm) as brackets. The antenna bracket is shown below.

Antenna Bracket

There are two installation methods:

1. Install between two panels, with an immersion distance of 60cm and an extension distance of 15cm (analyzed with PVsyst software, the impact on the system is negligible).

2. Set up on the rooftop lightning rod (since there are dozens of lightning rods on the roof, only occupying one, so the impact is negligible).

In terms of lightning protection, based on the average annual thunderstorm days of 40 days in Jiaxing City, on-site thunderstorms are divided into direct lightning and indirect lightning. The insulation of the PVC pipe does not consider indirect lightning strikes, with a coefficient above P90.

Since a wireless solution was chosen, a gateway needed to be installed to receive monitoring data from the combiner boxes. The gateway communicates with the communication management machine through RS485 wired communication. The communication management machine is in the inverter room, so the gateway is placed on the roof of the inverter room. The site distribution is shown below:

Satellite Map of the Distribution of Combiner Boxes and Gateways

Among them, the MW1 junction box monitoring is the farthest from the entrance, with a straight-line distance of 161 meters, two roof shields, and a height difference of about 10 meters. The MW11 combiner box monitoring is the closest to the gateway, with a straight-line distance of 36 meters and no obvious obstructions.

The on-site renovation situation is shown in the example below:

Comparison Diagram Before and After Combiner Box Modification

Wireless Communication Antenna Placement

For the placement of the gateway, considering that the gateway needs to communicate with the inverter through 485, and then the inverter wirelessly sends the data collected by the gateway to the data backend, the gateway can only be placed in the room where the inverter is located. On the roof, the power is supplied by AC 220V from the inverter room.

网关天线放置图

Communication Test Result: Upper computer test results showed that the monitoring data of all 15 combiner boxes were read correctly.

Thus, the junction box renovation project at the power station was perfectly concluded. From the initial on-site survey, to the design of the plan, and to the subsequent installation, Fonrich’s staff demonstrated outstanding professional skills. They used scientific methods and superb technology to make the old power station operational again, moving towards refined data management.