Hybrid Wind and Solar Systems as Renewable Energy Solutions

David Droz, Head of the Telecoms division at Urban Green Energy Inc., talks to AZoCleantech about Hybrid Wind and Solar Systems as Renewable Energy Solutions.

Can you provide a brief introduction to Urban Green Energy (UGE)?

Founded in 2008, UGE provides end-to-end distributed renewable energy (DRE) solutions. We understand that customers face a variety of energy challenges related to cost, reliability, and sustainability, and we deliver tailored solutions to address these needs.

We have offices in Barcelona, Mumbai, and Beijing, with our headquarters in New York City, and installations in over 70 countries around the world.

UGE and our staff believe in three core values: Be Green, Be Great, and Have Fun. We started UGE and work here because we believe in a greener future. We aim for nothing less than excellence in everything we do, and we do it with a smile.

How does the microprocessor-based controller and remote control options work with UGE technology?

Remote control and “smart” electronics are both key aspects of UGE’s technology, and we have developed a series of customized wind and solar controllers for both grid-tie and off grid applications.

For grid-connected systems, our SeamlessGrid™ inverter is a true hybrid inverter in the sense that it has inputs for both a wind turbine and solar panels.

Each channel has independent Maximum Power Point Tracking (MPPT) functionality, and the output connects directly to the electrical panel in your home or business.

It is equipped with many standard features, such as anti-islanding and phase/voltage matching to export power directly to the grid.

For off-grid systems, the wind controller incorporates a three phase rectifier, programmable MPPT, and low voltage (24 or 48V) output.

The “remote” aspect is really two parts: monitoring and control. ViewUGE monitors power and load channels, and also has the capability of controlling equipment on site. The remote control can be used to turn site specific equipment on and off. In most cases, this control is done automatically, such as turning on a diesel generator if batteries become discharged.

How does the braking control system work for UGE wind turbines?

The wind controller regulates the speed of the turbine by monitoring the voltage, and exporting power to the grid or batteries according to the MPPT table.

This transfer of energy takes away from the rotational kinetic energy of the turbine to keep it spinning at a safe RPM.  At very high winds, an additional resistor bank ensures that the controller always has enough load to keep the turbine spinning safely.

The automatic safety brake is an electromechanical device installed upstream of the controller.

In case of an emergency, high voltage from the generator triggers a relay, which crosses all three generator leads, and stops the turbine from overspinning. A second manual switch also allows any operator to stop the turbine, either in person, or remotely.

When wire leads from the three-phase permanent magnet are crossed, current induced in the coils immediately creates high resistance – enough to keep the turbine from overspinning in any wind condition. “Short circuiting” the generator in this way is how we control the wind turbine in high wind conditions.

What are the different mounting options for you turbines?

Although typically mounted on galvanized monopole steel towers, turbines can also be mounted to lattice towers, portable towers, roof structures, or even portable structures.

The loads, (namely weight and overturning moment force) and the natural frequency are the main parameters to consider.

What obstacles are likely to affect the function of wind turbines?

The function of the turbine itself is dependent on the wind – how fast the wind is flowing (velocity), how dense it is (relative to temperature and pressure), and how smooth it is (laminar or turbulent).

Obstacles that affect the turbine are those that interfere with the wind flowing into the turbine. The turbine can harness more energy from laminar wind flow, and when wind tends to “stick” to obstacles and cause swirling winds, this leads to less efficient turbine operation.

Any surface perpendicular to the wind flow (a wall), or high “roughness” (leafy trees), decreases the velocity of the wind and makes the flow less laminar.

What technology systems have you developed to combine wind and solar energy as a hybrid system?

The SeamlessGrid™ solution that I mentioned before includes our hybrid inverter, which combines wind and solar input channels into one grid-tie system. It’s “plug and play,” with two DC input channels which are combined into one smooth, grid quality output signal.

Wind and solar typically complement each other well, where we find they are inversely proportional. That is, during the day when the sun is shining, the wind decreases, and during the night when there is no sun, the wind increases.

Our proprietary site evaluation and system design tools determine just the right configuration of sun and wind to optimize power output.

How are these hybrid systems integrated into homes?

As I mentioned earlier, the mounting for wind is versatile, but typically a tall monopole yields the best production results.

Like siting for small wind turbines, siting solar panels is important to avoid shade. Solar can be easily roof or ground mounted. SeamlessGrid™ is all that is necessary to connect the system directly to the electric sub-panel in your home or business.

How does combining renewable resources benefit homeowners?

Output from wind and solar together increase energy reliability because it draws from multiple, independent resources. This is where the negative correlation between the frequency of the two sources also comes into play, yielding more consistent average output.

What are the principle benefits of your battery back-up systems?

Storing energy brings security when the utility fails. Even a small battery bank can be used to back up a critical systems sub-panel, powering lighting and refrigeration for days.

Larger banks can be used as an uninterruptible power supply (UPS) to fill in service gaps. For customers like retail banks and stores, this means never having to worry about a server going down, or the refrigeration turning off.

How do seasonal changes affect the battery back-up system used for your hybrid technology?

Each location has different wind and solar resources available during different times of year. During the site analysis process, we look at the back-up requirement (both time required and load required), and we balance this with the amount of solar and wind equipment installed.

Capacity factor, the ratio of energy produced over total rated installed capacity, is one way to measure the efficiency of these systems.

Can you discuss a case study on the commercial application of your technology?

In January 2012, 5 eddyGTs and 100kW of solar were installed at a central BMW dealership in Beijing as part of a significant renewable energy project.

The BMW dealership, Beijing Star Double, chose to decrease its impact on the environment by partnering with UGE. As the first authorized dealership of the new BMW 5S, the overall architectural and sustainable design of the building exceeded local green building standards.

Installation of 5 eddyGTs and 100kW of solar at the central BMW dealership in Beijing as part of a significant renewable energy project. Image Credit: Urban Green Energy Inc.

What challenges are facing the renewable energy industry and how will this impact on your technology and the development of your technology?

The renewable energy industry is facing challenges in Washington, in our communities and at home.

In Washington, inconsistent energy policy, such as the recent waffling on the PTC extension for wind power, mitigates investors’ ability to make long-term capital commitments.

Traditional subsidization of oil and gas outweighs the cash and tax breaks available for distributed generation at the federal level, and yet clean technologies seem to be facing the strongest political headwinds.

In our communities, utilities are fighting hard to keep their aging infrastructure operating while minimizing the expensive upgrade cost necessary to better integrate renewable energy.

Microgrids, propagation of electric vehicles (EV’s), and new power management platforms such as virtual power plants (VPPs) all require new laws, permit procedures, regulation, and construction.

At home, the “not in my backyard” (NIMBY) syndrome is waning but still prevalent. A basic understanding of how renewable energy can bring benefits, and a basic ability to afford change in a recovering economy, both limit adoption rates.

We believe the market for distributed generation will continue to grow quickly in the future, and it’s our job to continue to develop and deliver the right solutions to increase sustainability and reliability for customers while reducing cost.

How do you plan on improving the efficiency of a load system and how would this benefit the end-user?

The United States Green Building Council (USGBC’s) Leadership for Environmental Engineering and Design (LEED) program has been great to improve load system efficiency in construction.

Technology such as LED lighting, heat transfer designs used by architects, and ultra-efficient HVAC systems all help cut energy costs. Consumer products like the Nest thermostat augment this market by offering technology directly to end users to drastically slash energy consumption.

All of these approaches together make it easier for renewable energy, such as UGE’s hybrid solutions, to deliver high percentage offset or complete offset.

Can you discuss new technology currently being implemented to address the wide demand for energy storage and how is UGE addressing this demand?

Many new technologies currently being implemented come in two basic categories: power electronics, and financing.

The power electronics may seem more straightforward, with many flavors of “smart” power management solutions that can accommodate multiple inputs from renewables, back-up generators, and the grid, and adaptively select the cheapest source.

Financing (if you can consider financing to be a technology) can be equally disruptive, as new mechanisms for amortizing the capital expenditure (CAPEX) of installations become available to end users.

Companies like SolarCity did not invent the technology behind residential solar; they are successful in providing finance to appropriate customers which demonstrate economic savings from day 1. Likewise for Bharti Infratel’s application of “CAPEX-OPEX swaps” for telecoms operators in India.

UGE offers innovation in both of these areas, with complete energy solutions including power management and financing.

Where can we find further information on UGE technology?

Further information can be found at the Urban Green Energy website.

About David Droz

David manages the Telecoms division at UGE, where he is responsible for coordinating the deployment of UGE Fusion to remote telecom base stations around world. David has experience in engineering, product design, manufacturing, marketing and business development from various technology companies.

After completing a fellowship at Haifa’s Technion Institute of Technology, and a stint at Bell Helicopter in Texas, David moved to Israel, working as an aerospace engineer developing urban rotorcraft.

Returning to the US, David has shifted his focus from aerospace to energy, and uses that energy to run around the office in his socks. David is from Sixburgh, PA, and holds a bachelors of science in mechanical engineering with a concentration in aerospace from Drexel University.