We’ve heard a lot over the past several months about the unintended consequences of European government energy policies, with uncertainty in wholesale energy markets, rising electric rates and concerns about the stability of the grid in high penetration scenarios.
Distributed solar is certainly a piece of the transition underway in the European energy sector, particularly in Germany, where aggressive policies created the world’s largest solar market.
An encouraging view of how some of this disruptive change can be effectively managed came in a new report released by the European Union’s PV GRID program. It showcases the steps that can be taken to expand PV deployment while preserving grid reliability. It is encouraging to note that the authors of this detailed but accessible prescription represent a collaboration of utilities, research organizations and the solar industry.
The identified solutions are outlined on the table below. They are grouped into three categories based on the level of interaction between the utility and customers. Because solar resources are integrated into both the low voltage and medium voltage networks, the effectiveness of each solution is differentiated between those categories.
The DSO or utility solutions are all about managing voltage. These are steps utilities can take to stabilize their networks without actively engaging the root causes behind the customer meter. Load tap changers, static VAR control, curtailment and network reconfiguration are examples from this category.
If the distribution network is a still pond at 120 V, 60 Hz, then the Prosumer solutions PV GRID has identified will help generating customers avoid making waves. Each recommendation involves actions taken behind the meter to mitigate disturbances to the local grid by reducing the amount of energy that backfeeds onto the grid and better regulating the power that is exported.
The Interactive category includes the solutions that take advantage of a utility communications infrastructure that can harmonize distribution system management among all available grid assets on either side of the meter. These recommendations range from direct utility control of inverter operations to a holistic grid management strategy.
One key take away from the report is that the solutions from the DSO category are largely ready for deployment. These traditional utility solutions to voltage regulation such as transformers, load tap changers and network configuration are shown to be largely effective and technologically proven to aid the integration of distributed energy resources. Though the report originated in Europe, many of the findings should also translate to the U.S.
The report also suggests that the Prosumer or consumer solutions may yield the greatest impact. These solutions address the source of PV integration challenges from behind the meter by reducing the amount of energy exported to the grid by incentivizing onsite consumption or storage. Energy that is fed onto the grid is then used to support the distribution network by way of advanced inverter controls, reactive power support and time-shifted output from battery systems. Enacting policies pursuant to these solutions engages the generating customers to take a greater responsibility for their role in the larger utility system. Unlike the DSO category, these solutions will require significant regulatory changes and consumer and industry planning before implementation.
Perhaps the overall take away from this report is that the technologies already exist for the most effective of the identified solutions while several more can be reached through regulation and customer engagement. Energy storage, commonly viewed as the imminent killer app for PV integration, is only one of many potential tools to effectively manage high penetration of PV.