1.     The composition of solar photovoltaic lighting system

The home solar photovoltaic lighting system directly converts solar energy into electrical energy and supplies it to the lighting fixtures. The system generally consists of solar panels, batteries, controllers, DC-AC converters and lighting fixtures, etc.

solar panel

Convert sunlight directly into electricity.

Battery

Stores the electrical energy provided by the solar cell for use when needed.

Controller

The main purpose is to ensure that the system can work normally and reliably, and prolong the service life of system components (especially batteries). It must contain battery overcharge protection circuit, overdischarge protection circuit, overcurrent protection circuit and anti-reverse charge protection circuit, etc.

Converter

The converter converts the DC power output by the solar panel and the battery into AC and DC power required by the lighting appliances.

2.     Design of home solar photovoltaic lighting system

The system design focuses on efficiency and high reliability, as well as simple and convenient use and maintenance.

According to the local environmental conditions (geographical location, solar radiation energy, climate, weather, etc.), the size of the load and the time of daily use, and other use requirements, the system components are reasonably designed. Among them, solar panels and batteries have mature products. The converter of the system controller is the key point of system design, which is related to whether the system can work efficiently and reliably.

2.1 Partial design of solar energy

2.11 Calculation of solar panel power

The peak solar panel power required by the system is determined by the local average solar radiation and the electrical energy required by the load:

Pk=Pm·Ws/Wt·1KW/m^2

In the formula: Pk—the peak power of the solar panel, KWp

Ws—electric energy required by the load per day, KWh/d

Wt—the average daily square meter solar radiation energy KWh/(m^2·d)

Km-coefficient, considering the efficiency of each component, the influence of ambient temperature and other factors, the general value is 1.4-1.7. its value

The size should also be considered comprehensively according to the cost of the system and the specific situation of the user.

2.12 Battery capacity calculation

The watt-hour capacity Bw and the ampere-hour capacity BA of the battery are determined by the predetermined continuous no-sunshine time:

Bw=Kb·nb·Ws

BA=Bw/V

In the formula: Bw

—Battery watt-hour capacity, KWh

BA

—

Battery ampere-hour capacity, Ah

nb

—

Number of consecutive days without sunshine, d

V

—

system voltage

Kb-coefficient, which is determined by considering the factors of battery efficiency, depth of discharge, and ambient temperature, and is generally 2.0-2.5. Similarly, the value of the value should also be comprehensively considered according to the system cost and the specific situation of the user.

The general battery can be calculated by the formula: daily power consumption x continuous working days/discharge margin (0.7)/battery voltage = single battery capacity