Abstract
Standalone renewable energy systems usually incorporate batteries to get a steady energy supply. Currently, Li-ion batteries are gradually displacing lead-acid ones. In practice, the choice is made without previous comparison of its profitability in each case. This work compares the economic performance of both types of battery, in five real case studies with different demand profiles. For each case, two sets of simulations are carried out. In one of the sets, the energy demand is supplied by a standalone photovoltaic system and, in the other one, by a standalone hybrid photovoltaic-diesel system. Through optimization processes, the economic optimum solutions are obtained. In addition, sensitivity analyses on various parameters have been carried out, seeking the influence in favor of one or another type of battery. The results show that if the type of battery is changed, to achieve the economic optimum the entire system must be resized. In some cases, the economic optimum is reached with Li-ion and in others with lead-acid batteries, depending on the demand profiles. Thus, both types of batteries can be profitable options in standalone energy systems, with a greater tendency to lead-acid in fully photovoltaic systems and to Li-ion in hybrids. The price reductions that would make Li-ion the only choice is quantified.
Highlights
On-site renewable electricity generation is widely used in rural areas, where the electrical grid is weak, or it does not exist
Regarding storage in standalone systems, lead-acid batteries have been widely used [2], Li-ion batteries can be competitive in some cases [3] as their cost have been reduced recently
In addition to the price of Li-ion batteries, which is likely to change in the near future, it was intended to identify whether other parameters influence the comparative profitability of the two types of battery studied
Summary
On-site renewable electricity generation is widely used in rural areas, where the electrical grid is weak, or it does not exist. Standalone energy systems usually include a PV (photovoltaic) generator and battery storage. A hybrid system including PV, a fossil fuel genset (diesel or gasoline) and battery storage can be the optimal solution. The charge controller avoids the overcharge of the battery, preventing from premature failure. It controls the battery discharge, preventing the over-discharge. Inverters used in standalone systems include battery over-discharge protection. If the system includes a fossil fuel genset, a battery charger (rectifier, AC/DC converter) is used to charge the batteries. Regarding storage in standalone systems, lead-acid batteries have been widely used [2], Li-ion batteries can be competitive in some cases [3] as their cost have been reduced recently. DC coupled are usual in low power systems, while AC coupled are used in middle and large power systems
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