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Photovoltaic + Energy Storage Opens Up A New Pattern Of Photovoltaic Applications
- Apr 25, 2018 -


"Photovoltaic+energy storage" opens up a new pattern of photovoltaic applications


     “Solar energy conversion is an inexhaustible source of clean energy, but the electricity generated by solar energy cannot be kept constant. There must be energy storage equipment supporting operation.” Yang Yusheng, an academician of the Chinese Academy of Engineering pointed out at the 2018 China “PV + Energy Storage” technology fusion innovation application conference. The energy storage battery is an indispensable part of the microgrid. However, the existing energy storage technology in China can already fulfill its responsibility.


      Safety is a top priority for energy storage


      The existing chemical energy storage battery has high energy efficiency, flexibility, scale, and relatively rapid technological progress, but its disadvantages are also obvious. Yang Yusheng put forward the technical evaluation elements of the chemical energy storage battery from various perspectives and from various angles. He pointed out that only by requesting and standardizing it can he compete successfully and apply it to photovoltaic power plants.


      He divided the top ten performance requirements for large-scale energy storage batteries into three levels: the first one is high safety; the second one is high conversion efficiency, long cycle life, low price, and easy use. Product economic benefits are closely related; the third requirement is rich in resources, environment-friendly, cold and heat resistant, high specific energy, and high specific power. Only by satisfying these elements can technological progress be promoted and the cost of “photovoltaic + energy storage” can be reduced.


      Yang Yusheng stated that safety is the first element of evaluation of energy storage batteries. The burning of chemical energy storage batteries and the continuous occurrence of fires will bring great economic losses to photovoltaic power plants, which will seriously affect the development of today's chemical energy storage market.

"Absolutely safe batteries are not available, and various types of batteries may burn or explode," Yang Yusheng pointed out. First of all, the user must admit that the battery pack, like the fuel tank, is a kind of high-energy-containing part and has dangerous nature. .


      Second, use the battery as a flammable, explosive material and high voltage device. Finally, we must seriously study the measures to reduce the probability of battery accidents. The safety of various batteries varies greatly and should be treated appropriately.


      Lead-carbon batteries are widely used in energy storage power stations.“Economic efficiency is the second element of energy storage batteries. The direct economic benefits of energy storage can be derived from the initial investment, depth of filling and discharge, and operating costs, and many other indices can be calculated according to the formula. The longer the life, the lower the cost, the higher the energy efficiency. The higher the economic efficiency of the battery is,” Yang Yusheng said. In existing chemical energy storage batteries, lead-carbon batteries with safe, inexpensive and mature products are used in large-scale “photovoltaic + energy storage” power plants in China.


      Lead-carbon batteries have been used extensively in energy storage power stations because of their long life. Compared to other types of batteries, lead-carbon batteries are safe, environmentally friendly, have high specific power, resource recycling, long cycle life, and high energy conversion efficiency. Although the specific energy is lower than the lithium ion battery, and the cost is not low, the value of the waste battery is relatively high, and the price of the battery itself can be compensated to a certain extent.


      In contrast, lithium-ion batteries have high energy, high efficiency, high power, and relatively long cycle life, but their safety cannot be ignored.


      The electrolyte in lithium-ion batteries is formulated with flammable solvents. The oxidants and reductants on the positive and negative electrodes are separated by a layer of about 20 μm thick; when the battery pack is run (or parked), when The battery reaches a certain temperature, the oxidant and the reducing agent are easy to produce a large number of heat-generating chemical reactions with the electrolyte—thermal runaway.

Thermal runaway can easily cause a chain reaction. Once a large-scale energy storage occurs, the consequences will be disastrous. Therefore, if lithium ion batteries are used for energy storage, strict safety measures and management systems must be adopted.


      "PV + energy storage" application of a new pattern


      Today, the distributed photovoltaic market is booming. Household photovoltaics account for half of the photovoltaic market. In view of this situation, Yang Yusheng stated that it should vigorously develop small-scale photovoltaic power generation. He pointed out that small-scale "PV + energy storage" applications, the project does not have to be concentrated in the northwest, but should be built next to the user, so you can avoid long-distance transmission lines and line losses, in which to build wind power - photovoltaic - energy storage micro The grid can also be complemented with the big grid. In residential areas, in addition to the use of roofs, it is also possible to use walls to develop household photovoltaic energy storage systems.


      In addition, Yang Yusheng appealed to increase investment in research on energy storage batteries for new water systems. He pointed out that the special development of organic batteries, zinc-manganese batteries and other large-scale storage battery system, which may help develop the correct "photovoltaic + energy storage" development path, get rid of the current "feelings of stones across the river" dilemma.


      He suggested that the "photovoltaic + energy storage" application system should step up its demonstration to effectively verify its economic benefits. As long as the relevant policies are reasonable and both promote and not overdo it, they can enter the cycle of sound development. In addition, there should be no prejudice against various technological routes, so that each family can develop their own strengths, in order to make the market healthy competition, flourishing.


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