How much energy storage is usually provided in a photovoltaic power station

Energy storage requirements in photovoltaic power plants are reviewed. Li-ion and flywheel technologies are suitable for fulfilling the current grid codes. Supercapacitors will be preferred for providing future services. Li-ion and flow batteries can also provide market oriented services.

Li-ion and flow batteries can also provide market oriented services. The best location of the storage should be considered and depends on the service. Energy storage can play an essential role in large scale photovoltaic power plants for complying with the current and future standards (grid codes) or for providing market oriented services.

The photovoltaic installed capacity set in the figure is 2395kW. When the energy storage capacity is 1174kW h, the user's annual expenditure is the smallest and the economic benefit is the best. Fig. 4. The impact of energy storage capacity on annual expenditures.

To sum up, from PV power plants under-frequency regulation viewpoint, the energy storage should require between 1.5% to 10% of the rated power of the PV plant. In terms of energy, it is required, at least, to provide full power during 9–30 min (see Table 5).

Nonetheless, it was also estimated that in 2020 these services could be economically feasible for PV power plants. In contrast, in, the energy storage value of each of these services (firming and time-shift) were studied for a 2.5 MW PV power plant with 4 MW and 3.4 MWh energy storage. In this case, the PV plant is part of a microgrid.

When the electricity price is relatively high and the photovoltaic output does not meet the user's load requirements, the energy storage releases the stored electricity to reduce the user's electricity purchase costs.