Revolutionizing Solar Energy Integration: The MARS Project and Electric Grids

A new era of energy systems dominated by green and renewable solar power is approaching. As the transition comes to fruition, it’s important to understand the type of current the grids use – Alternating Current (AC) – and to ensure solar integration without much hassle. Despite its benefits, solar energy involves a complex and lengthy process from generation to supply and consumption.

Integrating DC Solar Power in AC Grids

Today our electricity is predominantly powered by alternating current. Alternating current (AC) is the type of electric current generated by the vast majority of power plants and used by most power distribution systems. It is cheaper to generate and has fewer energy losses than DC transmission.

Most devices directly connected to the electrical grid operate on alternating current, and electrical outlets in homes and commercial areas supply alternating current as well. Devices that require direct current, like laptops, usually have an AC adapter that converts alternating current to direct current.

However, the case is reversed with solar panels. Solar panels produce DC as the sun’s rays stimulate the flow of electrons, creating a current that flows in a single direction. This direct current needs to be converted to AC using inverters so it can be used in the home or sent back to the electric grid.

As the penetration of utility-scale solar photovoltaic (PV) power plants increases, there will be increased primary frequency response requirements. In short, managing solar integration, transmission, and storage will become much more complicated. The need of the hour is some system to give stability to the grid.

Enduring Solution

Grid-forming inverters connecting PV to grid and energy storage systems (ESSs) may play an important role in solar power integration in grids. High-voltage direct current (HVDC) links can also be an enabler to transfer remote PV power generation and improve grid stability. That is, with increased penetration of PV, discrete development of PV and ESS connecting to transmission AC grid and HVDC links can be one of the solutions for stable operation of the grid.

ORNL’s MARS Project

The US Department of Energy’s Oak Ridge National Laboratory has developed a game-changing utility-scale solar and storage project named MARS (Multi-port Autonomous Reconfigurable Solar Power Plant). The project is an all-in-one package that includes power electronics, electrical architecture, and cybersecurity software. It is designed to provide power to both AC and DC high-voltage lines, making it possible to transmit renewable energy more easily and reliably. MARS converts current between DC and AC using specialized power electronics.

One of the most exciting features of MARS is its plug-and-play design, which makes it easy and cheap for utilities to get online. Additionally, the project has achieved impressive results in case simulations. Based on two California sites, MARS achieved up to a 50 per cent reduction in power loss, a 16 per cent improvement in stabilizing AC voltage frequency, and a 100 per cent detection of cyber intrusions.

Furthermore, MARS can also reconfigure itself based on available energy. For example, when the solar panels aren’t generating electricity at night, MARS can continue to connect the AC and DC transmission systems and use stored battery power to supplement its operation. This feature allows MARS to reduce electrical costs by up to 40 per cent, as the researchers developed an algorithm to fine-tune plant size and energy storage to maximize annual revenue. In all, the project acts as a catalyst for solar integration with the grid.

The capacity of global solar PV is projected to increase threefold from 2022 to 2027, overtaking coal as the leading source of power generation worldwide. Solutions like MARS will be more needed as solar power gets more widely adopted.