Clip-on wind turbine aims to supplement solar panels
By Mike Barnard
August 1, 2013
Crowdfunding has come to the small wind generation field with an Indiegogo campaign intended for an interesting target niche: a small wind generator designed to be clipped onto solar panels. According to its pitch, Cleantec Wind has not only created a prototype, but calculated possible energy returns, targeted a price point and lined up suppliers for initial deliveries and has turned to Indeigogo to get his small startup off the launch pad.
Cleantec's idea is to add lightweight narrow-profile wind generators to the top edge of solar panels. This would put the wind generators a few feet above the ground and in the very turbulent air that will exist in a hot solar array with wind blowing across it. This is an interesting proposal. The solar panels already generate electricity and are already tied into the grid for that purpose. (However, solar farms are engineered for the weight of the panels, the shadows that the panels cast and the output of the solar farms, so the prospect of strapping on a wind generator poses some challenges.)
Another interesting element is the Indiegogo campaign itself. Cleantec has created a range of low-end to high-end rewards for contributions, including working devices. The company has a simple prototype and renderings which do not reflect what they consider the final product.
The wind generator itself is a fairly standard multi-blade Savonious drag generator, which means its output will likely be lower than Darrieus or tri-blade horizontal-axis wind turbines. That's acceptable if the niche fits the generator and price point is appropriate for the amount of energy produced, but we wonder if a Darrieus generator would be a better fit. Both Savonius and Darrieus wind generators have axes parallel to the blades and are typically referred to as vertical-axis wind turbines. The difference is that a Savonius generator uses drag only to capture energy from the wind and has greater upwind drag on the opposite side, while Darrieus blades typically have an aerodynamic component for added speed, lower upwind drag and hence greater generative capacity. Textbooks since the '70s have included standard graphs of power curves for these types of devices.
The generator is claimed to produce 2000 W output, greater than a typical solar panel it might be attached to. At present, any test data or independent testing of the prototype that might have been used to validate the 2000 W is not publicly available from the company's website or the Indiegogo campaign site, though Cleantec's intent is to make it more efficient with such things as curved blades to catch wind from more angles, magnets to reduce resistance to lower start speed and high-efficiency bearings. Such optimizations are familiar on small wind generators like this, and have not historically proven to be economically justifiable when full lifecycle cost of electricity calculations are done. There are many of these types of devices that possibly could be retrofitted for the niche at lower cost via an OEM model rather than creating a new one from scratch, and this might be a direction Ring could choose to go if the engineering difficulties start to mount.
Though the proposed device may not be perfect, Cleantec's suggested an interesting niche for small-scale distributed wind, potentially increasing the output of solar farms in the day and yielding generation at night.