The inverter as the PV industry’s linchpin

By Lior Handelsman, VP of Marketing and Product Strategy and Founder of SolarEdge

Although solar energy has been steadily growing over the past 15 years, it currently constitutes only about 3% of global electricity generation. In order to accelerate its proliferation rate and increase its portion of the energy mix, there are three separate, yet interconnected advancements that need to happen simultaneously. The first is at the product level, in which individual components of the PV system need to be improved, such as panel and inverter efficiencies. The next is at the PV system level, in which there needs to be increased synchronization between the different products and components for a seamless operation and user experience. The last is at the network level, where PV systems need to be fully synced with the grid to create a dynamic distributed energy network. 10hp Vfd

The inverter as the PV industry’s linchpin

At the intersection of all of these technology advancements lies the inverter. Since the inverter has an interconnected relationship with all of these areas, it acts as a linchpin for progress both behind the meter and for grid development.

Nearly a decade ago, consumers required multiple gadgets, such as calculators, GPS systems, cameras, alarm clocks and more to perform tasks in their everyday lives. However, today, one piece of hardware provides all of these functions — the smart phone. Just like smart phones, smart inverters are now seamlessly integrating functions that were previously performed by separate pieces of hardware. This means that the PV inverter has taken on a much wider and more strategic role within the PV system.

Entirely surpassing its original purpose of managing solar energy, the inverter has now become an energy manager and is responsible for managing and synchronizing all energy production, consumption, and storage that occurs behind the meter. Acting as the brain of a PV system, its role has expanded from simply converting energy from DC to AC to including a plethora of functions, such as communications, monitoring, safety, managing energy storage, providing backup power, controlling home appliances and even charging EVs.

At the same time, and due to its role in behind-the-meter functionality, the inverter is taking on a larger role in dynamic grid interaction. Because the inverter acts as a gateway between the grid and behind the meter, it is ideally positioned to help stabilize the grid, versus just feed energy into the grid.

This role is particularly critical at this point in time as PV penetration and other distributed energy resources (DERs) are beginning to create grid instability. An inverter’s role in providing grid stability is demonstrated by the implementation of Rule 21, which calls for smart inverters to provide advanced functionalities such as remote connection/disconnection, max power controls and anti-islanding protection, low and high voltage and frequency ride-through, voltage variation mode, power factor control, power ramp-up during startup and normal operation, remote powering and curtailment, and frequency-watt and voltage-watt control.

A key reason that the inverter is pivotal in maintaining grid stability is due to its ability to communicate with and manage a variety of DERs, such as EVs, IoT devices, PV, batteries and more. This interoperability between multiple types of DERs is key for achieving a more flexible and dynamic grid. This is because being able to communicate and control DERs allows them to be aggregated in the cloud for the deployment of virtual power plants (VPPs). While the software and user interface is an essential part of VPPs, the inverter is responsible for receiving commands and implementing them, such as charging or discharging batteries for an energy shortage scenario.

With the inverter significantly impacting both the grid and behind the meter, its advancement sets the pace for the progress of the entire PV industry. For the inverter to continue to lead the industry forward, it requires increased processing power, advanced computing and improved memory capabilities. This coupled with advancements in grid-edge computing and machine learning will yield a new demand-flexible grid that can unlock value from existing DERs and increase benefits for all grid stakeholders.

Lior Handelsman founded SolarEdge in 2006 and currently serves as our Vice President of Marketing and Product Strategy in which he is responsible for defining and steering SolarEdge’s strategic global marketing activities, media outreach, product roadmap and vision, corporate product strategy, as well global product management, and corporate business development. Prior to founding SolarEdge, Mr. Handelsman spent 11 years leading power electronics research and development teams and directing large-scale, multidisciplinary research and development projects. Mr. Handelsman holds a B.S. in Electrical Engineering (cum laude) and an MBA from the Technion, Israel’s Institute of Technology.

From the article: “A key reason that the inverter is pivotal in maintaining grid stability is due to its ability to communicate with and manage a variety of DERs, such as EVs, IoT devices, PV, batteries and more. This interoperability between multiple types of DERs is key for achieving a more flexible and dynamic grid. This is because being able to communicate and control DERs allows them to be aggregated in the cloud for the deployment of virtual power plants (VPPs). While the software and user interface is an essential part of VPPs, the inverter is responsible for receiving commands and implementing them, such as charging or discharging batteries for an energy shortage scenario.”

I find it interesting that the solar PV inverter technology is so expensive per watt of inverted power. The industrial community have had VFDs or variable frequency drives for decades that have many of the functions of the solar PV inverter built into the VFDs software and hardware. An 11 to 12kW solar PV inverter costs around $4,500 but a 20 H.P. VFD, about 15kW, can be bought for around $2,500. The VFD needs only a battery charger module for charging energy storage batteries. Most of the VFD manufacturers have some Wi-Fi or ZigBee communications built in.

im intrested in designing my pv system currently on net metering to be able to function when the power is interupted.I understand the logistics of why the system was designed this way. Any resorces that might be available would be appreciated.

You say you have a net metered system and want to be able to function when the power is interrupted. What is happening now is the concept of ‘self consumption’. This requires energy storage and programming software that allows the ‘system’ to use power in the most efficient manner. The adoption by the electric utilities of using TOU and shifting peak demand times of the day to the 3PM to 9PM hours erodes your net metered system payback. Since now you get the off peak residential rate for energy credits and will pay double or triple for Peak demand rates.

I have seen three self consumption systems, they all have a battery storage system, that requires an inverter with a built in battery charger. TESLA has their power wall 2.0, LG Chem has their high voltage 350 to 400VDC and could be integrated into an existing simple series/parallel panel string of high voltage DC feeding a house inverter. There is Panasonic and one that I have actually seen installed in a home is Sonnen 10kWh system. This system comes typically in 10kWh or 20kWh of lithium ion storage, it has a radian 8kW inverter with built in 48VDC battery charger, so it might not be the best choice for your net metered system. At that, I have seen schematics that use the Sonnen system and a transfer switch to allow power to be switched to a secondary circuit breaker panel that can power some of the homes receptacles, fans, lights, refrigerator/freezer and microwave during a power outage.