As the war between Russia and Ukraine intensifies, home PV energy storage systems are once again in the spotlight of power freedom, and choosing which battery is better for your PV system has become one of the biggest headaches for consumers. As a leading lithium battery manufacturer in China, we recommend Solar Lithium Battery for your home.
Lithium batteries (or Li-ion batteries) are one of the most modern energy storage solutions for PV systems. With better energy density, longer lifetime, higher cost per cycle and several other advantages over traditional stationary lead-acid batteries, these devices are becoming increasingly common in off-grid and hybrid solar systems.
Why choose Lithium as a solution for home energy storage? Not so fast, first let's review what types of energy storage batteries are available.
The use of lithium ion or lithium batteries has grown significantly in recent years. They offer some significant advantages and improvements over other forms of battery technology. Lithium-ion solar batteries offer high energy density, are durable and require little maintenance. In addition, their capacity remains constant even after long periods of operation. Lithium batteries have a life span of up to 20 years. These batteries store between 80% and 90% of their usable capacity. Lithium batteries have made huge technological leaps in a number of industries, including cell phones and laptops, electric cars and even large commercial aircraft, and are becoming increasingly important for the photovoltaic solar market.
On the other hand, lead-gel batteries have only 50 to 60 percent of their usable capacity. Lead-acid batteries also cannot compete with lithium batteries in terms of lifetime. You usually have to replace them in about 10 years. For a system with a 20-year lifespan, that means you have to invest twice in batteries for a storage system over lithium batteries in the same amount of time.
The forerunners of the lead-gel battery are lead-acid batteries. They are relatively inexpensive and have mature and robust technology. Although they have proved their worth for over 100 years as car or emergency power batteries, they cannot compete with lithium batteries. After all, their efficiency is 80 percent. However, they have the shortest service life of around 5 to 7 years. Their energy density is also lower than that of lithium-ion batteries. Especially when operating older lead batteries, there is a possibility of explosive oxyhydrogen gas forming if the installation room is not properly ventilated. However, newer systems are safe to operate.
They are best suited for storing large amounts of renewably generated electricity using photovoltaics. The areas of application for redox flow batteries are therefore currently not residential buildings or electric vehicles, but commercial and industrial, which is also related to the fact that they are still very expensive. Redox flow batteries are something like rechargeable fuel cells. Unlike lithium-ion and lead-acid batteries, the storage medium is not stored inside the battery but outside. Two liquid electrolyte solutions serve as the storage medium. The electrolyte solutions are stored in very simple external tanks. They are only pumped through the battery cells for charging or discharging. The advantage here is that it is not the size of the battery but the size of the tanks that determines the storage capacity.
Manganese oxide, activated carbon, cotton and brine are the components of this type of storage. The manganese oxide is located at the cathode and the activated carbon at the anode. The cotton cellulose is usually used as a separator and the brine as an electrolyte. Brine storage does not contain any substances harmful to the environment, which is what makes it so interesting. However, in comparison - the voltage of lithium-ion batteries 3.7V - 1.23V is still very low.
The decisive advantage here is that you can use the surplus solar energy generated in summer only in winter. The application area for hydrogen storage is mainly in the medium and long-term storage of electricity. However, this storage technology is still in its infancy. Because the electricity converted to hydrogen storage has to be converted from hydrogen to electricity again when needed, energy is lost. For this reason, the efficiency of storage systems is only about 40%. Integration into a photovoltaic system is also very complex and therefore cost intensive. An electrolyzer, compressor, hydrogen tank and a battery for short-term storage and of course a fuel cell are needed. There are a number of suppliers that offer complete systems.
While lead-acid batteries have given lithium batteries the opportunity to take the lead because of their constant need to refill acid and environmental pollution, cobalt-free lithium iron phosphate (LiFePO4) batteries are known for their strong safety, the result of an extremely stable chemical composition. They do not explode or catch fire when subjected to dangerous events such as collisions or short circuits, greatly reducing the chance of injury.
Regarding lead-acid batteries, everyone knows that their depth of discharge is only 50% of the available capacity, in contrast to lead-acid batteries, lithium iron phosphate batteries are available for 100% of their rated capacity. When you take a 100Ah battery, you can use 30Ah to 50Ah of lead-acid batteries, while lithium iron phosphate batteries are 100Ah. But in order to extend the life of lithium iron phosphate solar cells longer, we usually recommend that consumers follow 80% discharge in daily life, which can make the battery life of more than 8000 cycles.
Both lead-acid solar batteries and lithium-ion solar battery banks lose capacity in cold environments. The energy loss with LiFePO4 batteries is minimal. It still has 80% capacity at -20˚C, compared to 30% with AGM cells. So for many places where there is extreme cold or hot weather, LiFePO4 solar batteries are the best choice.
Compared to lead-acid batteries, lithium iron phosphate batteries are almost four times lighter, so they have a greater electrochemical potential and can offer greater energy density per unit weight - providing up to 150 watt-hours (Wh) of energy per kilogram (kg) compared to 25Wh/kg for conventional stationary lead-acid batteries. For many solar applications, this offers significant benefits in terms of lower installation costs and faster project execution.
Another important benefit is that Li-ion batteries are not subject to the so-called memory effect, which can occur with other types of batteries when there is a sudden drop in battery voltage and the device starts to work in subsequent discharges with reduced performance. In other words, we can say that Li-ion batteries are "non-addictive" and do not run the risk of "addiction" (loss of performance due to its use).
A home solar energy system can use only one battery or several batteries associated in series and/or parallel (battery bank), depending on your needs.
Two types of systems can use lithium-ion solar battery banks: Off Grid (isolated, without connection to the grid) and Hybrid On+Off Grid (connected to the grid and with batteries).
In the Off Grid, the electricity generated by the solar panels is stored by the batteries and used by the system in moments without solar energy generation (during the night or on cloudy days). Thus, supply is guaranteed at all times of the day.
In Hybrid On+Off Grid systems, the lithium solar battery is important as a backup. With a bank of solar batteries, it is possible to have electric energy even when there is a power outage, increasing the autonomy of the system. In addition, the battery can function as an additional source of energy to complement or alleviate the energy consumption of the grid. Thus, it is possible to optimize energy consumption at times of peak demand or at times when the tariff is very high.
See some possible applications with these types of systems that include solar batteries:
Remote Monitoring or Telemetry Systems;
Fence electrification - rural electrification;
Solar solutions for public lightings, such as streetlamps and traffic lights;
Rural electrification or rural lighting in isolated areas;
Powering camera systems with solar energy;
Recreational vehicles, motorhomes, trailers, and vans;
Energy for construction sites;
Powering telecom systems;
Powering autonomous devices in general;
Residential solar energy (in houses, apartments, and condominiums);
Solar energy for running appliances and equipment such as air conditioners and refrigerators;
Solar UPS (provides power to the system when there is a power outage, keeping the equipment running and protecting the equipment);
Backup generator (provides power to the system when there is a power outage or at specific times);
"Peak-Shaving - reducing energy consumption at times of peak demand;
Consumption Control at specific times, to reduce consumption at high tariff times, for example.
Among several other applications.