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How do solar photovoltaic energy storage systems match lithium battery packs?

08 Jan, 2022

By hoppt

energy storage system

The solar photovoltaic energy storage system is currently the most widely used energy storage system in the market. In off-grid photovoltaic energy storage systems, lithium battery packs are critical components. So how to match the lithium battery pack? Share this today.

Solar photovoltaic energy storage system--solar street light

  1. First, determine the voltage platform series of the solar photovoltaic energy storage system
    At present, many photovoltaic energy storage system voltage platforms are 12V series, especially off-grid energy storage systems, such as solar street lights, solar monitoring equipment energy storage systems, small portable photovoltaic energy storage power supplies, and so on. Most of the solar photovoltaic energy storage systems using 12V series are energy storage systems with a power of less than 300W.

Some low-voltage photovoltaic energy storage systems include: 3V series, such as solar emergency lights, minor solar signs, etc.; 6V series, such as solar lawn lights, solar symbols, etc.; 9V series of photovoltaic energy storage systems are also many, between 6V and 12V, some solar street lights also have 9V. Solar photovoltaic systems using 9V, 6V, and 3V series are small energy storage systems below 30W.

solar lawn light

Some high-voltage photovoltaic energy storage systems include: 24V series, such as football field solar lighting, medium-sized solar photovoltaic portable energy storage systems, the power of these energy storage systems is relatively large, about 500W; there are 36V, 48V series Photovoltaic energy storage systems, the emphasis will be more significant. More than 1000W, such as home photovoltaic energy storage systems, outdoor portable energy storage power supplies, etc., the power will even reach about 5000W; of course, there are larger photovoltaic energy storage systems, the voltage will reach 96V, 192V series, these especially high-voltage photovoltaic energy storage systems are large-scale photovoltaic energy storage power stations.

The home photovoltaic energy storage system

  1. Matching method of lithium battery pack capacity
    Taking the 12V series with the giant batch in the market as an example in technology products, we will share the matching method of lithium battery packs.

At present, there are two aspects to match; one is the power supply time of the energy storage system to calculate the match; the other is the solar panel and the charging sunshine time to match.

Let's talk about matching the capacity of a lithium battery pack according to the power supply time.

For example, a 12V series photovoltaic energy storage system and a 50W power solar street light need to have 10 hours of lighting every day. It is necessary to consider that It cannot charge on three rainy days.

Then the calculated lithium battery pack capacity can be 50W10h3 days/12V=125Ah. We can match the 12V125Ah lithium battery pack to support this photovoltaic energy storage system. The calculation method divides the total number of watt-hours required by the street lamp by the platform voltage. If It cannot charge on cloudy and rainy days, it is necessary to consider increasing the corresponding spare capacity.

Country Solar Street Light

Let's talk about the method of matching the capacity of the lithium battery pack according to the solar panel and the charging sunshine time.

For example, it is still a 12V series photovoltaic energy storage system. The output power of the solar panel is 100W, and the adequate sunshine time for charging is 5 hours per day. The energy storage system needs to charge the lithium battery within one day fully. How to match the capacity of the lithium battery pack?

The calculation method is 100W*5h/12V=41.7Ah. That is to say, for this photovoltaic energy storage system, we can match the 12V41.7Ah lithium battery pack.

the solar energy storage system

The above calculation method ignores the loss. It can calculate the actual use process according to the specific loss conversion rate. There are also different types of lithium battery packs, and the computed platform voltage is also different. For example, a 12V system lithium battery pack uses a ternary lithium battery and needs three series-connected. The platform voltage will be 3.6V3 strings=10.8V; The lithium iron phosphate battery pack will use 4 in series so that the voltage platform will become 3.2V4=12.8V.

Therefore, a more accurate calculation method needs to be calculated by adding the system loss of the specific product and the corresponding specific platform voltage, which will be more accurate.

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