China’s DAH Solar has added a specially designed micro-inverter to its full-screen module, making the “SolarUnit” a formidable offering for the rooftop segment. DAH Solar president Shenheng Xie took pv magazine through some of the key features of the system and the benefits they promise after installation.
With its latest release, DAH introduces a module with a built-in microinverter – which market are you targeting with this product?
Our modules leave the factory pre-integrated with microinverters, which makes them very well suited for smaller projects, such as balcony modules, which we are seeing more of, especially in Europe. Without an additional inverter, we offer a “plug and play” device that users can easily connect to their home circuit and generate electricity for their own consumption.
The system we deliver has one microinverter for every two or three modules. This configuration offers advantages in low light and is also suitable for larger ceilings, allowing the modules to be installed at several different angles and directions without limiting each other’s performance. This means systems can achieve better roof coverage and production throughout the day.
What other advantages do you see in this AC module design?
Our modules and microinverters are designed for each other and come pre-assembled as a single unit, whereas other AC module systems require assembly and rely on different brands of modules and microinverters that may not be ideally suited to each other. Our solar unit achieves 97.55% maximum system efficiency, an industry leading figure.
It is also a very safe system with an energy control unit that allows for module level monitoring and quick shutdown. Overall, our integrated system achieves a higher return on investment: the system can produce more electricity, and labor and installation costs are significantly reduced.
The full-screen modular design also promises to cut cleaning costs – what can you tell us about this?
The unique front frame design with no raised edge allows water to drain freely from the module. So no water stays on the surface of the module and no dust accumulates on the edge of the frame. Dust accumulated on the surface of the module is easily washed away immediately after rain. We have data from field installations that show a 6-15% increase in energy yield due to this feature, and it also helps to reduce the costs associated with cleaning the modules from time to time.
Frame design will add about 0.03-0.05 CNY ($0.0043-0.0072) per watt price of the module, so it’s worth it for this increase in energy output.
What type of cell does this module use?
In the past, we have worked with PERC cells, and now we are completing an upgrade of our 5.5 GW generation capacity to work with TOPCon.
We cut the cells into three parts, this keeps the current low. And this also works well with a microinverter to keep currents low throughout the system, minimizing temperature rise and associated power loss.
How does the price compare to a traditional module+inverter system?
It’s a bit more expensive, but much of that can be offset by an easier and faster installation time. For systems with a maximum of five kilowatts, the price is approximately the same. As the systems grow, the additional cost of the microinverter starts to show. However, the subsequent increase in energy production means we can still be competitive with some of the larger commercial sized plants. And that’s why we’re targeting the roof market because we can offer our customers a clear advantage here.