SHAC implements smart homes and also handles the installation of photovoltaic systems. In order to simplify the operation of both systems, they approached us with the requirement to create a complex control unit with touch screen control – SMART Control Center, through which all devices in the house, including PV, will be connected.
It is not such a big challenge to develop and manufacture such a unit and we already have experience in the field of photovoltaics, but in this case we had to take into account the security of the data that can be obtained from both systems.
Most of the components used in the PV plant come from China and are automatically connected to Chinese clouds. This issue and its solution are currently being discussed and a warning about Chinese technology has been issued by the National Cyber Security Bureau (NCSB).
A smart home works with data on traffic, consumption and user behaviour, and neither system wishes to allow data to go uncontrolled abroad or for systems to be exposed to external attacks.
This project was therefore not only about the functional unification of the PV plant with the smart home into a device that is easy to operate, but also about ensuring that all communication takes place within a controlled infrastructure (preferably purely local) and not on foreign servers with questionable security levels.
Electronics design for unified communications and safe operation
In order for the SMART Control Center to take over the communication for the original Chinese components and become the central point of the entire system, we had to design electronics that could handle the wide range of interfaces used in photovoltaics and smart home.
The basis of the unit is the NXP i.MX8 microprocessor, which runs applications under its own Linux operating system builder (Yocto); Docker is also used to run the application. The board itself has integrated interfaces that cover the most common connectivity requirements:
- 4× RS485 for connecting inverters, monitoring modules and other PV systems,
- 2× Ethernet for separation of traffic between the building network and the PV plant internal network, if implemented by Ethernet,
- data SIM, which enables a backup connection to the Internet via LTE in case of unavailability of the main Internet connectivity.
- Wi-Fi and Bluetooth for local access and integration,
- USB port as an option for future expansion with specialised converters.
Design for wall and cabinet mounting
While the electronics design was a fairly standard job for us, the installation solution proved to be more complex. The customer needed the unit to be able to be installed in two ways: on a wall indoors and also in a cabinet. Both types were to use one common design, without the need to produce two different versions of the device.
At the same time, SHAC did not want to reach for a ready-made plastic box, but had a requirement for a custom designthat will match their technical and aesthetic brief. This made it possible to design the assembly exactly according to their needs, but it also significantly increased the technical complexity of the mechanical solution.
We finally solved it by designing a structure primarily intended for mounting in a switchboard, supplemented by a separate bracket for wall installation. This created a system that satisfies both mounting methods while maintaining a uniform set of plastic parts. For the prototypes currently being tested, we printed the design on a 3D printer, but for mass production SHAC plans to approach an external injection moulding company to manufacture the plastic parts.
Cooling in minimal space is solved by a special fan
Another challenge of this project was to come up with a suitable ventilation to prevent the processor from overheating. The overall depth of the design is only 33 mm, which is very little for a touchscreen device with a more powerful processor.
A normal axial fan did not fit in the space, so we chose a low radial fan, which is often used in laptops. It draws air in from the side, exhausts it out through the exhaust vents and allows for even flow even in a narrow interior space.
The SMART Control Center is now in test operation with SHAC customers and the project is ready for the next phase – the production of plastic moulds and the start of mass production.
SMART Control Center shows that even conventional electronics can be designed to operate in a closed, controlled and safe environment. And that’s what custom development is all about – addressing technical limits, functionality and safety from the start, not just when a problem occurs.
