Battery Energy Storage System (BESS)

Solar energy is intermittent. Electricity production on a rainy or cloudy day could be very far from what you get in a sunny and bright day. The most obvious solution to this unpredictability is energy storage. Energy Storage System (ESS) relies on battery technology, a common way of storing electrical energy transforming it into electrochemical energy to be used at a later time.


For solar PV applications, VRLA (valve regulated lead acid) battery and Li-ion BESS (Battery Energy Storage System) are the main technologies so far.


Deep cycle VRLA batteries are the type most suited to energy storage to ensure that they have a long enough life span for this use. Lithium ion batteries are commonly found in modern consumer electronics and electric vehicles. They have a high energy density. The main benefits with lithium ion batteries are deeper DoD (Depth of Discharge), longer life span (higher numbers of charge/discharge cycles), fast charging capability and lower weight. Other promising technologies such as flow battery and fuel cell are poised to scale-up and offer alternative storage solutions in the near future.


A typical Li-ion battery based ESS is composed of battery modules and BMS (battery management system), PCS (power conditioning system) and EMS (energy management system) for safety and power management.


BESS helps to effectively use and manage your energy that leads to the reduction of the electricity bill. Various solutions can be configured and applied for example: charging a battery with low-priced night time electricity and cutting electricity cost by lowering peak demands (i.e., buy low sell high).


Especially, Residential BESS makes green energy 24/7 available in association with the solar PV system. Electricity is getting more expensive in countries. ESS stores daytime energy from PV and makes it available at any time, minimizing electricity purchase from the grid, which results in increased energy self-consumption at home and reduced overall electricity charges. In addition, rural areas where the power grid hardly covers can have stable and cheap electricity from PV system using ESS. Additionally, it can be used as an emergency power source when an unexpected interruption occurs.