The smart energy system provided for the Rubik's Cube Apartment this time is an independent photovoltaic power generation system, using an off grid inverter and complementary AC power supply from the city.

Independent photovoltaic power generation systems are relative to grid connected power generation systems. A typical independent photovoltaic power generation system consists of a solar array and connected batteries. When there is sunlight, the photovoltaic power generation array provides power to the load and charges the battery, while in other cases, the battery provides power to the load. Using an inverter to convert the DC power of the array and battery into 60Hz or 50Hz power. Inverters with a wide range of rated power can be utilized, with efficiency ranging from 85% to 95%. In order to improve reliability, the array can be divided into insulated diodes in blocks. In this design, if a string of solar arrays fails, the failed part will not become a load on the remaining part or short-circuit it.

Off grid photovoltaic power generation system solution

To design an off grid photovoltaic power generation system, it is necessary to first understand the project requirements

It mainly consists of the following elements

1. Where are solar power generation systems used? What is the solar radiation situation in the area?

2. What is the load power of the system?

3. What is the output voltage of the system, DC or AC?

4. How many hours does the system need to work per day?

5. If encountering cloudy and rainy weather without sunlight, how many days does the system need to be continuously powered?

6. What is the starting current for the load, pure resistive, capacitive, or inductive?

JDSOLAR off grid photovoltaic power generation system has obvious advantages compared to conventional power generation systems, especially traditional thermal power generation, mainly reflected in the following aspects

1. No risk of depletion;

2. Safe and reliable, no noise, no pollution discharge, clean and clean (pollution-free);

3. Not limited by the geographical distribution of resources, can utilize the advantages of building roofs;

4. Local power generation and supply can be achieved without the need for fuel consumption and the installation of transmission lines;

5. High energy quality;

6. The construction cycle is short, and the time required to obtain energy is short.

In this scheme, JDSOLAR technical engineers have designed a complementary photovoltaic power generation system for users,

The complementary photovoltaic power generation system for urban electricity refers to an independent photovoltaic power generation system that mainly relies on solar photovoltaic power generation, supplemented by ordinary 220V AC power. In this way, the capacity of solar cells and batteries in photovoltaic power generation systems can be designed to be smaller. Basically, when there is sunlight on the day, solar energy is used to generate electricity, and when encountering cloudy and rainy days, municipal energy is used to supplement it. Most regions in China have had over two-thirds of sunny weather for many years, which not only reduces the one-time investment in solar photovoltaic power generation systems, but also has significant energy-saving and emission reduction effects. It is an excessive and effective way to promote and popularize solar photovoltaic power generation at this stage.

JDSOLAR off grid photovoltaic power generation system generally consists of a photovoltaic array composed of solar cell components, solar controller, inverter, battery pack, load, etc.

The photovoltaic array converts solar energy into electrical energy under illumination, and supplies power to the load through a solar controller, inverter (or reverse control integrated machine), while charging the battery pack; When there is no light, the battery supplies power to the AC load through the inverter.

Main equipment of off grid photovoltaic power generation system

01. Photovoltaic modules

Photovoltaic modules are an important component of off grid photovoltaic power generation systems, whose function is to convert solar radiation energy into direct current energy. Radiation characteristics and temperature characteristics are two major factors that affect the performance of components.

02. Inverter

An inverter is a device that converts direct current (DC) into alternating current (AC) to meet the electricity demand of AC loads.

According to the output waveform, inverters can be divided into square wave inverters, stepped wave inverters, and sine wave inverters. The characteristics of sine wave inverters are high efficiency, low harmonics, and can be applied to all types of loads, with strong load carrying capacity for inductive or capacitive loads.

According to the topological structure, it can be divided into high-frequency inverters and power frequency inverters (the difference lies in whether there is a power frequency transformer)

03. Controller

The main function of a photovoltaic controller is to regulate and control the direct current energy emitted by photovoltaic modules, and to intelligently manage the charging and discharging of batteries. The off grid system needs to be equipped with appropriate specifications of photovoltaic controllers based on the DC voltage level and system power capacity of the system. Photovoltaic controllers are divided into PWM type and MPPT type, with common DC12V, 24V, and 48V voltage levels.

04. Battery

A battery is an energy storage device in a power generation system, which stores the electrical energy emitted by photovoltaic modules and supplies power to the load during power consumption.

05. Monitoring

3. System Design and Selection Explanation Design Principles: On the premise of meeting the power consumption needs of the load, use the least amount of photovoltaic modules and battery capacity to minimize investment.

01. Photovoltaic module design

Reference formula: P0=(P × T × Q)/（ η one × T) In the formula: P0- peak power of the solar cell module, in Wp; P - Power of the load, in W; T - The daily electricity consumption hours of the load, in H; η 1- refers to the efficiency of the system; T - Local daily average peak sunshine hours, unit HQ - Surplus coefficient during continuous rainy periods (usually 1.2-2)

02. Photovoltaic controller design

Reference formula: I=P0/V

In the formula: I - control current of the photovoltaic controller, unit A; P0- Peak power of the solar cell module, in Wp; V - The rated voltage of the battery pack, in volts. ★ Note: In high-altitude areas, photovoltaic controllers need to amplify a certain margin and reduce capacity for use.

03. Off grid inverter

Reference formula: Pn=(P * Q)/Cos θ In the formula: Pn - capacity of the inverter, in VA; P - Power of the load, in W; Cos θ—— The power factor of the inverter (usually 0.8); Q - The margin coefficient required for the inverter (usually 1-5). ★ Note: a. Different loads (resistive, inductive, capacitive) have different starting impulse currents, and the selected margin coefficients are also different. b. In high-altitude areas, inverters need to amplify a certain margin and reduce capacity for use.

04. Lead acid batteries

Reference formula: C=P × T × T/(V × K ×η 2) In the formula: C - capacity of the battery pack, in Ah; P - Power of the load, in W; T - The daily electricity consumption hours of the load, in H; V - Rated voltage of the battery pack, in volts; K - The discharge coefficient of the battery, determined by considering battery efficiency, discharge depth, environmental temperature, and influencing factors, generally ranging from 0.4 to 0.7; η 2- Efficiency of the inverter; T - Continuous rainy days.