With the popularity of solar panel systems, more and more families are trying to use solar panel systems to power their household appliances and expect to reduce some of their household electricity expenses in this way. However, it is worth noting that solar panel systems are still very expensive at present. Therefore, for the average family, in order to improve the power supply capacity of the solar system and save as much money as possible, most of the home solar panel systems will be equipped with other components such as solar battery packs to achieve the purpose of improving the power supply capacity. Based on this, the question of how many batteries should be equipped with different sizes of solar panel systems in order to achieve efficient operation is one of the key concerns in the industry. In this article, we will introduce you to the most popular scale of home solar panel system on the market – 400W solar panel system, and how many batteries are needed for its supporting solar panel and other related issues.

1. What is a 400W solar panel system?

Most of the solar panel system sizes on the market will be measured in wattage values. Relevant international organizations measure the size of a solar panel system as follows:

Experimenters will completely expose a certain size of solar panel to an artificial light source with an intensity of 1,000W/m2, and then record its power generation and the value of electricity it is able to produce in one hour.

The 400W solar panel system represents that the system receives 1000W/㎡ light intensity per hour under the premise of its rated power generation is 400W.

2. How to calculate the number of batteries needed for a 400W solar panel system?

First of all, we need to know that the number of batteries needed for a 400W solar panel system depends largely on its generating capacity, and the generating capacity of the solar panel system, under the premise of the rated power being determined as 400W, depends mainly on the daily peak sunshine hours. When these two data are known, the calculation of daily power generation wattage can be carried out by the following formula:

P total (W) = P (W) x T (h)

According to the average level of each region, it may be assumed that the average daily peak sunshine duration is 5h, and solar panels are good at generating electricity during the peak sunshine period, then the electricity produced by the 400W solar panel system in a day is 400W × 5h = 2000W.

And most of the battery packs within the current solar panel system are measured in Ah, and it is known that the operating voltage of a 400W solar panel system is usually 12V, so the conversion from daily wattage to battery capacity can be realized according to the following formula:

E (Ah) = P total (W) ÷ V (v)

The value of Ah for the battery bank within this system should then be 2000W ÷ 12v = 160Ah.

However, in practice, due to the lack of concentration of sunlight resources, as well as shading objects near the property, the actual battery capacity should be between 80-140Ah. Therefore, when equipping a 400W solar panel system with a solar battery pack, its battery capacity should be above 140Ah, and in the event of a sufficient budget, it is also possible to choose a battery pack with a capacity of 160Ah.