Solutions for Grid Stability

A Primer on the Electric Grid

To understand the significance of Apparent’s technology, an overview of how the electric grid functions follows.

Electricity runs down wires to power your home and electronics.

The power to meet the energy demands of consumers is produced by power plants, collectively referred to as Independent Generators. The Independent Generators transmit power to consumers using a network of transmission systems known as the grid. To balance the production of power and the variable demand for energy, the grid relies on Independent System Operators (“ISO”). ISOs operate designated regions that cover multiple states and even countries. ISOs coordinate with Independent Generators telling them to power up or down in order to meet demand and keep the grid voltage within appropriate ranges. If the voltage increases above or decreases below acceptable ranges, the grid can shut down, causing ISO-wide loss of electricity; the most well-known example of which is the Northeast Blackout of 2003 (see Figure 2).  Fluctuations within the grid force ISOs to be able to react dynamically to balance production and transmission with demand as needed.

A Fundamental Problem

Power consists of real power (Watts) that is used to perform work, and reactive power (VAR) that helps to maintain magnetic fields to allow induction necessary for alternating currents to work. The combination of both Watts and VARs is total, or apparent, power. Real and reactive power must be balanced in order to be transmitted to a consumer, as well as to allow alternating current motors to operate. When the grid was first established, voltage fluctuations did not produce state-wide or regional electricity losses. One reason is demand: in general, the primary loads requiring power were resistive and required little reactive energy to operate. Contemporary electronics and modern appliances require much greater reactive power to operate. The demand to operate contemporary electronics means that ISOs must transmit more reactive power to consumers. Another reason is the dissipation of power: reactive power dissipates by rates of up to 30% more than real power. Independent Generators and ISOs must produce and transmit greater amounts of reactive power to consumers.

Figure 2: A rolling blackout drops the Northeast in darkness.

ISOs have to compensate for the need for reactive power by contracting with Auxiliary Generators for reactive power, referred to as Ancillary Services. Only Independent Generators capable of producing consistent real and reactive power are allowed to participate in the Ancillary Services Market. Coupled with the Ancillary Service Market is the Day Ahead Market where Independent Generators sell power, both real and reactive, based upon predictions about production and demand. Today, PV Systems do not participate in Ancillary Service or Day Ahead Markets because, until Apparent, no PV System could consistently produce real and reactive power on demand.

In the PV energy segment, conventional inverters produce only real power and are limited by weather conditions, requiring ISOs to rely on increased support from Auxiliary Generators to balance production and demand. As a result at peak times, ISOs prevent utility PV systems from delivering power to the grid because of the disruptive impact the generation of real power alone has. PV systems are, thus, prevented from earning revenue and lose significant money as they can neither sell nor store power.

Where We Fit In

The current solutions to balancing power production, delivery, and demand include generating more power, building capacitor banks to store and release reactive power, building VAR generators used solely for the purpose of producing reactive power, or imposing tariffs to manage use, are inefficient and do not permit renewable energy systems to participate in the grid. Apparent offers a different solution: through a combination of a unique software system and hardware technology, Apparent has developed technology that allows greater extraction of power from renewable sources, that allows the production of reactive power with less loss of real power, and delivers real and reactive power on demand. Apparent’s technology is demonstrated initially in the first grid-smart micro-inverter.

IMT gathers complete information by using impedance, the sum of resistance and reactance, to measure optimum power output, rather than only resistance.

Apparent’s micro-inverter has several qualities that allow it to outperform string and other micro-inverters. For starters, other solar inverters use the conventional standard for power extraction MPPT, Maximum Power Point Tracking, while Apparent utilizes its own patented extraction technology. MPPT probes a PV system with a resistance load to test for and extract power at the maximum power output. In doing so, it does not extract any power generated at less than resistance maximum output. Apparent’s patented DMZ, or Dynamic Impedance Matching technology, extracts power at all settings and exceeds MPPT’s optimization technology.

Not only does the Apparent grid-smart micro-inverter produce more real power, it produces reactive power without the losses of real power suffered by conventional inverters and produces reactive power upon demand. This means that Apparent’s micro-inverter can produce apparent power at the direction and demand of an ISO. As a result, Apparent’s micro-inverter is the only PV inverter that can qualify to produce Ancillary Services and can participate in the Day Ahead Market.

Apparent’s technology as deployed in a micro-inverter is versatile for installation and application. Apparent’s technology can be installed in distributed generation systems throughout urban areas where demand is high and the cost of building generators, or capacitor banks is prohibitive. Distributed generation eliminates inefficiencies and losses in reactive power inherent in the production of power at remote generators and distribution over distances to consumers.

Apparent’s technology offers solutions to critical inefficiencies plaguing the grid and does so by using the existing infrastructure and within the current technology. Apparent advances the renewable energy market with practical, focused, and realistic steps leading to the ultimate goal of making renewable energies competitive without reliance on rebates and tariffs.