America’s booming solar industry has been hit hard by supply chain disruption and inflationary pressures from Covid, the war in Ukraine and trade restrictions with China. As a result, the utilization rate of solar energy decreased by 40 percent compared to the corresponding period in 2022.
For many project owners, power distribution, not construction, makes the most sense to increase generation capacity because it uses existing land, grid connection points, and other infrastructure. Adding power again will help maximize the project’s return on investment (ROI), which can help offset losses incurred during the recent slowdown. Many of the country’s solar projects are already nearly 10 years old – with 8 GW of assets providing power in the coming year.
Renewable energy planning
Identifying optimal power recovery time starts with an intelligent asset management strategy that addresses predictable and unexpected performance issues and opportunities to maximize system yield. Changing market dynamics and new applications can make upgrading solar power plants with new technology a profitable decision.
In order to successfully plan for the maximum return on a renewable investment, asset managers must understand the key technical challenges and commercial benefits of the optimization operation, as well as the most suitable technology.
When inverters have a lifespan of 5-10 years, replacement can become difficult as manufacturers quickly switch to higher system voltage products. Instead of defaulting to older inverters that may not be available, are less efficient, lack modern technology, and cost more per watt than newer products; system owners can use an inexpensive adapter to allow newer inverters added to an existing system to run at full rated output.
The voltage drop is usually caused by a faulty aspect of the project, such as accelerated module degradation, and results in the DC bus voltage being below the level required by the inverter to produce AC at full power. Solving problems related to voltage drops can be a catch-22: matching spare parts are expensive to find and require manpower to replace, but if nothing is done, system owners lose revenue from reduced energy production. Additionally, replacing a large number of modules or changing inverters can further complicate voltage mismatch losses. To solve the problem, the DC bus voltage must be stable and operate at a fixed voltage so that it is always within the operating range of the inverter to ensure the long-term health of the system.
Solar modules are installed to withstand harsh outdoor conditions, but the modules are inevitably damaged and degraded. More efficient modules can significantly improve your system’s ROI, so replacing panels before they experience performance issues is a good preventative measure. However, mixing modules with different output characteristics causes an electrical mismatch in the system, which often leads to significant performance losses.
Historically, inverter load ratios (ILRs) – the ratio of solar panel DC output to inverter AC output – were significantly lower than today. Increasing the ILR improves revenue because the system can produce more power even during low sunlight. The problem with increasing the ILR of an existing system is that during high sunlight, the amount of DC generated by the PV array can exceed the rated capacity of the inverter. The challenge is to find a way to increase the ILR while staying within the operating range of the inverter.
As solar cells and modules naturally degrade over time and at different rates, voltage imbalances and mismatches between strings can affect system performance. Integrating string-level maximum power point tracking (MPPT) is a well-known enhancement approach to mitigate such effects. Many multi-megawatt systems use string inverters to increase array MPPT resolution compared to a central inverter, but introducing string inverters into an existing system is expensive, often requiring expensive, labor-intensive rewiring.
Connecting solar power plants to storage is on the rise as project owners seek to take advantage of tax incentives or solve performance issues where the inverter often limits output. Adding storage also helps meet grid demands and changing electrical load profiles. Unfortunately, it comes with the aforementioned limitations of adding DC and upgrading inverters. Additionally, adding storage components to the adjustable voltage DC bus between the inverter and solar array can be complex to program, difficult to control, and requires expensive battery converters that must both step up and step down the voltage during charging or discharging.
Adding renewable energy is a profitable investment for many solar projects, but it is not challenging. By identifying the right supporting technology, system owners can mitigate the aforementioned technical limitations while significantly controlling costs.
DC-DC conversion technology allows project owners to replace old inverters without rewiring and correct voltage drop without replacing modules or inverters. It eliminates the string compatibility issue when mixing new and old modules, and the ILR of the system can be increased without overloading the inverter or the electronic BOS (Balance of System) system to generate and deliver more energy. The DC-DC conversion also recovers the energy lost from the breakdown of solar cells and modules and from other sources of voltage imbalance in a much more economical way than the introduction of inverters. Finally, DC-DC conversion technology makes it possible to add DC-coupled storage more cheaply, as battery converters only need to decrease the voltage during charging and increase the voltage during discharging.
A good power distribution strategy shows that solar assets are not just something to monitor and maintain, but can generate additional revenue with built-in, future-proof flexibility. Thanks to the features and capabilities offered by DC-DC conversion technology, system owners can maximize annual project returns over the life of their portfolio and better compete to meet the growing demand for clean energy.
About the author: Levent Gun is CEO of Colorado-based solar technology manufacturer Ampt and has decades of experience in technical and senior management roles in the solar, smart grid, wireless and semiconductor industries. Before Amptia, Levent was CEO of Kleer, a wireless audio semiconductor company acquired by SMSC; and Iospan Wireless, which was acquired by Intel. Levent also co-founded and managed USRobotics’ cable data business.