ZigBee is increasingly becoming a strong solution for the new smart home, providing a reliable and robust connection between home systems like air conditioning and heating, home security, door and window locks, home health monitoring, and energy use monitoring and management, as well as in home entertainment.
Various flavors of ZigBee are being used to connect these home subsystems to the cable set-top box (STB). From the STB, they can be directly managed by a ZigBee Radio Frequency for Consumer Electronics (RF4CE) remote control, or by using an Internet connection. A smart phone or other Web-connected device also can be used to control them remotely. And, ZigBee can be used to monitor and control the roof-mounted solar panel systems for homes and small businesses.
Throughout the world, solar energy is rapidly becoming one of the most widely employed alternative energy sources. Because of lower manufacturing prices and rising energy costs, photovoltaic (PV) solar panel systems are rapidly increasing in popularity. The technology continues to evolve, improving the efficiency of solar cells and inverters and reducing the overall cost of installation and operations.
But in many ways, PV systems are still in the early stages of design maturity. Most installations are still built quite simply with few sophisticated components. For example, a typical home or business location array consists of a PV panel, a simple junction box with Schottky diodes to bypass the panel in case of failure, and a central inverter to feed power back to the home or to the grid.
A more sophisticated measurement and tracking system will help home and business users to better understand, monitor, and maintain PV installations. Therefore, each junction box on the PV modules needs to have some additional logic to measure their performance parameters and wirelessly feed this data back to a central monitoring and control unit. Such a mechanism will allow the consumer or service provider to track the system performance and provide warnings or maintenance and cleaning alerts on an individual panel basis.
The most critical real-world issue that negatively impacts solar panel power output is simply dust, dirt, fallen leaves, or even algae growing on the surface of the panel. Unless they routinely climb on the roof to inspect their panels, homeowners typically have a difficult time recognizing a panel’s partial failure.
The total energy produced by a battery of panels linked in series (e.g., on a rooftop) tends to be limited to the output of the least performing panel. By monitoring the quality of each panel, users can optimize overall performance by cleaning off dirty panels or switching off non-performing panels, so the total output power level stays as high as possible.
The ability to remotely monitor each panel individually would give homeowners and building and service operators greater control over all the panels. Wireless smart junction boxes can be added to each individual panel. Each of these boxes would talk to the home’s STB and from there to a remote control or smart phone. Immediate access to information about the electricity generation of each panel then becomes available, and the operator or homeowner can choose to switch off panels or panel substrings for better overall performance.
Another major concern for PV installations is safety. Depending on the size of the installation and the number of modules in series, dc voltages that are quite high can be present in these solar panel installations.
Imagine a fire in a building topped by a large solar panel. The high voltage from solar panels on rooftops can be dangerous for emergency services or fire responders. Emergency responders are understandably reluctant to climb on roofs during a fire because of the electrical shock potential from active PV panels. Combining high power with water and other conductors is dangerous.
So how can this danger be quickly remedied? Some tests have tried to cover the panels with substances such as foam to stop them from generating power. However, the results were unsatisfactory. The foam, for example, slides off or doesn’t provide enough shielding.
Of course, we can’t turn off the sun. But we can install an on/off switch that can be remotely triggered from the ground or from inside the building. According to industry experts, new legal requirements will require emergency on/off switches for solar panels to prevent the risk of electrocution. Adding remote control to this capability will make it even safer and more efficient.
The GreenPeak Technologies Smart Junction Box reference design includes these functions. A remote control using RF provides long life, exceptional range, and reliability. And unlike infrared remote controls, RF remotes don’t have to be pointed at the on/off switches to activate them. This solution could be implemented in several ways. The facility manager or homeowner could use the remote to turn off the system for maintenance or in an emergency.
The ability to individually monitor solar panels is just one new example of how many residential applications are advancing, giving owners more control over energy consumption, lighting, HVAC, and more. Although many of these systems are developed as separate entities and are released to the market as isolated systems, the information shared between systems, and between consumers and service providers, will improve usage models. Opportunities for optimizing energy consumption will multiply.