Bluetooth, an open wireless technology used for exchanging data over short distances, is rapidly proving to represent the future of photovoltaic (PV) plant communication.

From configuration and maintenance, through to retrieval of spot values, it saves installers time and cables while giving operators a simple and state-of-the-art plant monitoring system. It has been a standard feature of new generation inverters for a while now, and this year it was added to the new SMA Sunny Beam and the SMA Sunny Explorer PC software.

Frank Tempke, proprietor of German installation company RegEnSys, has been working with SMA Bluetooth since its inception. He has already linked a large number of private roof systems via wireless connection, and he recently installed one solar power system which is equipped with five new generation inverters and has an installed capacity of 25.76 kilowatt peak (kWp). The house is still under construction, and while there is no telephone or other communication devices installed, Bluetooth makes it possible for the operator to retrieve the output of the PV system from his laptop. As Frank says, “It’s a great invention not only for small systems, but also for medium-sized plants in the open field.”

According to Lydia Pieworeit from SMA, Bluetooth technology is particularly suited for small, private roof systems. However it can also be used in solar power plants with up to 50 devices and a maximum capacity of 100 kW.

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All SMA products are Bluetooth-enabled, so when installed they are automatically linked into a wireless network.

“Prior to installation there are certain recommendations to bear in mind,” explains Lydia. “In order to use Bluetooth, you need a NetID, and the inverters need to be set to this NetID. This prevents any involuntary connections occurring between neighboring systems.”

Retrieval devices such as the Sunny Beam, or a PC with Sunny Explorer, recognise the set NetID and connect automatically to these inverters.

“People often have reservations about the vulnerability of wireless networks to interference,” acknowledges Lydia. To alleviate these concerns, SMA uses Bluetooth Class 1, with a range of up to 100 metres in free field between devices. By comparison, a standard mobile phone communicates via Bluetooth Class 2 with a range of just 10 metres. Thanks to constant frequency changes and the transmission of data packets in small units, the wireless connection is extremely stable.

Case study: added convenience for older plants

Lothar Burhenn from North Hesse, Germany, used Bluetooth as an aid in upgrading an existing customer plant. The Brandl family required a simple solution for monitoring their plant. The data logger Sunny Boy Control, which did not have remote access, was located in the garage of their home. This meant that regular monitoring of the system was inconvenient, and the technology was somewhat out of date.

Instead of replacing the old system, Lothar simply upgraded the inverters to enable the new Bluetooth wireless technology.

He explains “To achieve this, all we had to do was retrofit Bluetooth Piggy-Backs to the three inverters, install Sunny Explorer on the customer’s computer and log the inverters in. The entire installation work, including commissioning, was completed in just one hour. And the Brandl family can now monitor the current yield of their system whenever they like on their computer.”

Lothar is absolutely certain about the promise of Bluetooth.

“Our case demonstrates clearly that the new Bluetooth technology is ideal not only as a convenient and cost-effective solution for monitoring new plants, it is also highly suitable for modifying or upgrading existing systems.”

Frank Tempke agrees. “In the future, there will be no getting around Bluetooth technology. Bluetooth gives you so many benefits, especially with the introduction of the new Sunny Explorer software.”