Against the backdrop of intensified global climate change and increasingly severe energy security situation, a profound energy revolution is unfolding globally. As an important component of this revolution, photovoltaic power generation technology is moving from the industrial sector to millions of households due to its clean, renewable, and widely distributed characteristics, becoming the core driving force for modern household energy security. Especially in China; Dual Carbon; Under the guidance of the goals of peaking carbon emissions before 2030 and achieving carbon neutrality before 2060, the position of photovoltaic systems in the household energy structure is becoming increasingly prominent.
As the basic unit of society, the energy consumption pattern of the family directly affects the energy transformation process of the entire society. Traditionally, household energy supply has been highly dependent on centralized power grids, facing multiple risks such as electricity price fluctuations and unstable power supply. The introduction of photovoltaic systems not only provides clean and renewable sources of electricity for households, but also gives them energy autonomy, enabling them to; Producers and consumers "; The Prosumer model becomes possible - households are both energy consumers and producers. This transformation not only has economic significance, but also represents the rise of a new way of life and energy values.
1. Technical composition and evolution of photovoltaic systems
1.1 Basic Architecture of Photovoltaic System
A complete home photovoltaic system typically consists of five core components:
(1) Photovoltaic modules: as a component of the system; Heart "; Responsible for converting solar energy into direct current. At present, the mainstream photovoltaic modules in the market include three categories: monocrystalline silicon, polycrystalline silicon, and thin-film cells. Among them, monocrystalline silicon modules have become the first choice for the household market due to their high conversion efficiency (up to 22% -24%) and long lifespan (over 25 years).
(2) Inverter: As a key device for converting electrical energy, it converts the direct current generated by photovoltaic modules into alternating current that can be used in households. Modern inverters have evolved from simple electrical energy conversion devices to intelligent devices with functions such as intelligent monitoring and grid interaction.
(3) Energy storage system: Lithium ion batteries are usually used to store excess electricity generated by photovoltaic systems, achieving; Peak shaving and valley filling; Improve energy self-sufficiency rate. The addition of energy storage systems enables off grid operation of household photovoltaic systems, greatly enhancing the reliability of energy supply.
(4) Bracket system: Fix photovoltaic modules and adjust their angles to maximize sunlight reception. With the development of Building Integrated Photovoltaics (BIPV) technology, support systems are gradually being integrated into building structures, such as photovoltaic roof tiles, photovoltaic curtain walls, etc.
(5) Monitoring and Management System: Real time monitoring of system operation status through intelligent sensors and communication modules, optimizing power generation efficiency, and remote control through a mobile app. Advanced energy management systems can also be linked with household electrical equipment to achieve intelligent scheduling.
1.2 Innovative breakthroughs in key technologies
In recent years, photovoltaic technology has continued to make breakthrough progress, mainly reflected in the following aspects:
(1) Efficient battery technology: PERC (passivated emitter and back cell) technology has become mainstream in the market, with a conversion efficiency of 22% -24%. The efficiency of more advanced TOPCon (Tunnel Oxide Passivation Contact) and HJT (Heterojunction) batteries has exceeded 25%, and the laboratory efficiency has reached over 26%. Perovskite solar cells, as the next generation technology, have achieved a laboratory efficiency of over 30%. Although commercialization still faces stability challenges, their prospects are broad.
(2) Component technology innovation: Technologies such as half cell batteries, double-sided power generation, and multiple main grids have significantly improved the power generation efficiency and reliability of components. Especially for double-sided power generation components, by utilizing reflected light from the back, an additional 5% -20% increase in power generation can be achieved, making them particularly suitable for installation in complex terrain home environments.
(3) Progress in energy storage technology: The energy density of lithium batteries continues to increase, and costs are rapidly decreasing. Lithium iron phosphate batteries have become the preferred choice for household energy storage due to their high safety and long cycle life (up to 3000-5000 cycles). New energy storage technologies such as sodium ion batteries are also rapidly developing, which may further reduce energy storage costs in the future.
(4) Intelligent control technology: The application of AI algorithms enables energy management systems to predict weather, electricity prices, and household electricity demand, achieving optimal scheduling of power generation, energy storage, and consumption. The popularization of IoT technology enables distributed photovoltaic systems to participate in virtual power plants (VPPs), providing auxiliary services such as frequency regulation and peak shaving for the power grid.
2. Economy and return on investment of photovoltaic systems
2.1 Initial Investment and Cost Composition
The initial investment composition of a typical 5kW household photovoltaic system (including basic energy storage) is as follows:
(1) Photovoltaic modules: accounting for about 40% -50% of the total investment, the current market price is about 1.8-2.2 yuan/W, and the cost of 5kW system modules is about 9000-11000 yuan.
(2) Inverter: Approximately 10% -15%, priced at around 2000-3000 yuan.
(3) Energy storage system: accounting for about 20% -30%, the price of a 5kWh energy storage system is about 10000-15000 yuan.
(4) Installation and auxiliary materials: accounting for about 10% -15%, including brackets, cables, distribution boxes, etc.
(5) Design and labor: approximately 5% -10%.
Overall, the initial investment for a 5kW household photovoltaic system is between 25000 and 35000 yuan, and with technological advancements and economies of scale, the cost continues to decline.
2.2 Analysis of Operating Revenue and Returns
The benefits of home photovoltaic systems mainly come from three aspects:
(1) Self generated electricity cost savings: Assuming an annual power generation of 6000 kWh, a self consumption ratio of 70% (4200 kWh), and a local residential electricity price of 0.6 yuan/kWh, the annual electricity cost savings are approximately 2520 yuan.
(2) Surplus electricity grid connection income: The remaining 30% of electricity (1800 kWh) is connected to the grid at the local desulfurization coal benchmark price (about 0.35 yuan/kWh), with an annual income of about 630 yuan.
(3) Policy subsidies: Some regions still retain household photovoltaic subsidies, such as a subsidy of 0.05-0.1 yuan per kilowatt hour, with an annual subsidy income of about 300-600 yuan.
Based on comprehensive calculations, the annual revenue of a 5kW system is approximately 3450-3750 yuan, with a static investment payback period of about 7-10 years. Considering that the system has a lifespan of over 25 years, the long-term economic returns are significant. If we consider the factor of future electricity price increases, the actual return rate will be higher.
2.3 Cost Decline Trend and Future Outlook
In the past decade, the cost of photovoltaic power generation has decreased by over 80%, and this trend continues:
(1) Component cost: It is expected that by 2025, the price of photovoltaic modules will decrease to 1.3-1.5 yuan/W, a further 25% -30% decrease from the current level.
(2) Energy storage cost: The price of lithium batteries has decreased from $1000/kWh in 2010 to $132/kWh in 2022, and is expected to further drop below $100/kWh by 2025.
(3) System efficiency: The combination of efficient components and intelligent control can increase the overall efficiency of the system by 10% -15%, which is equivalent to reducing the cost of electricity per kilowatt hour.
The cost reduction will further shorten the investment payback period and improve the economic competitiveness of photovoltaic systems.
3. Policy Environment and Market Driving Factors
3.1 International Policy Support and Market Dynamics
Governments around the world are using various policy tools to promote the development of household photovoltaics
(1) Subsidies and Incentive Policies: Germany's; Renewable Energy Law; (EEG)、 The Federal Investment Tax Credit (ITC) in the United States and residential photovoltaic subsidies in Japan have effectively stimulated the household photovoltaic market.
(2) Net metering policy: allows photovoltaic users to sell excess electricity back to the grid at retail prices, improving system economy.
(3) Renewable energy quota system: By legislation, grid operators are required to purchase a certain proportion of renewable energy electricity.
According to data from the International Energy Agency (IEA), household photovoltaics accounted for over 40% of the global new distributed photovoltaic installations in 2022, with Europe, North America, and the Asia Pacific region being the main markets.
3.2 China's Policy Framework and Development Status
The Chinese government has passed the; Top level design+local innovation; The model promotes the development of home photovoltaics:
(1) At the national level: 14th Five Year Plan; The Renewable Energy Development Plan clearly proposes the concept of distributed photovoltaics; County wide Promotion; Strategy; The Implementation Plan for Promoting High Quality Development of New Energy in the New Era simplifies the approval process for distributed photovoltaics.
(2) At the local level, provinces such as Zhejiang, Shandong, and Hebei have introduced local subsidy policies; Guangdong, Jiangsu and other places are promoting; Photovoltaic+Energy Storage; Demonstration project; Shanghai, Beijing and other major cities are exploring the integration of urban building photovoltaics.
(3) Market situation: As of the end of 2022, the cumulative installed capacity of household photovoltaics in China exceeded 50GW, with an additional 25.25GW of installed capacity added in 2022, a year-on-year increase of 17%, accounting for nearly 60% of the new installed capacity of distributed photovoltaics. Shandong, Henan, and Hebei are the top three markets for household photovoltaics.
3.3 Analysis of Market Driving Factors
The rapid growth of the home photovoltaic market is driven by multiple factors:
(1) Energy security demand: events such as the Russia-Ukraine conflict highlight the risk of energy supply, and home PV can provide a certain degree of energy autonomy.
(2) Economic improvement: With the decrease in costs, photovoltaic power generation has the ability to compete with traditional energy sources.
(3) Enhanced environmental awareness: Consumers, especially the younger generation, are pursuing a low-carbon lifestyle.
(4) Electricity marketization reform: Mechanisms such as time of use electricity prices and spot markets have made the economic value of photovoltaic+energy storage more prominent.
(5) Integration of real estate and construction industry: New residential buildings equipped with photovoltaics have become a trend, and there is huge potential in the existing building renovation market.
4. The impact of photovoltaic systems on household energy security
4.1 Enhancing Energy Independence and Security
Photovoltaic systems provide homes with; Self owned power supply; Its value is particularly prominent in the following aspects:
(1) Coping with power grid failures: Photovoltaic systems equipped with energy storage systems can maintain basic electricity demand during power outages, ensuring critical loads such as lighting, communication, and refrigeration.
(2) Stabilize electricity price fluctuations: reduce dependence on grid electricity and lower the risk of rising electricity prices.
(3) Enhancing adaptability to extreme weather conditions: In the event of power grid disruptions caused by natural disasters, photovoltaic+energy storage systems can become a viable option; Lifeline "; Power Supply.
After the Fukushima nuclear accident in Japan, the demand for household photovoltaic energy storage systems surged; Areas with frequent wildfires in California; Photovoltaic+Energy Storage; It has become an important choice for ensuring power supply.
4.2 Reducing Electricity Costs and Electricity Fee Management
Photovoltaic systems help households save electricity costs in various ways:
(1) Directly replacing grid electricity: reducing the amount of electricity purchased from the grid and directly lowering electricity bills.
(2) Peak valley electricity price arbitrage: Charging during low price periods and discharging during high price periods to profit from price differences.
(3) Participate in demand response: Reduce electricity consumption during peak hours of the power grid and receive economic compensation.
Some families in California, USA, have passed the; Photovoltaic+Energy Storage; The system has reduced electricity costs by 30% -50%.
4.3 Promoting Energy Consumption Transformation and Carbon Reduction
The popularization of household photovoltaics has a significant impact on energy structure transformation and carbon reduction:
(1) Reduce fossil energy consumption: The annual power generation of each kilowatt of photovoltaic is about 1200-1500 kWh, which can replace about 0.5 tons of standard coal and reduce about 1.2 tons of CO2 emissions.
(2) Promoting Building Energy Efficiency: Building Integrated Photovoltaics (BIPV) technology transforms buildings from energy consumers to producers.
(3) Cultivate low-carbon lifestyle habits: The use of photovoltaic systems often prompts households to pay more attention to energy efficiency, further reducing overall energy consumption.
According to calculations, if the household photovoltaic penetration rate in urban areas of China reaches 30%, the annual emission reduction can reach hundreds of millions of tons of CO2, making a significant contribution to achieving carbon neutrality goals.
5. Challenges, Trends, and Future Prospects
5.1 Current Challenges
Despite the broad prospects, the development of home photovoltaics still faces many challenges:
(1) Initial investment threshold: Although costs continue to decrease, it still poses a burden on some low-income families.
(2) Grid access and consumption: High proportion distributed photovoltaics may have an impact on local power grids, requiring support from smart grid technology.
(3) Standards and Regulation: The rapid development of the industry has brought about problems such as lagging standards and uneven quality.
(4) Recycling and reuse: The recycling and disposal system for photovoltaic modules after their end of life is not yet perfect.
(5) Policy uncertainty: Subsidy reduction, local protectionism, and other factors may affect market stability.
5.2 Future Development Trends
Based on current technology and market trends, home photovoltaics will present the following development trends in the future:
(1) Integrated photovoltaic energy storage and charging: The photovoltaic system is deeply integrated with household energy storage and electric vehicle charging stations to form a complete household energy ecosystem.
(2) Virtual power plant participation: Distributed photovoltaics will participate in the electricity market through aggregators, providing auxiliary services such as frequency regulation and peak shaving, and creating new sources of income.
(3) Integrated innovation in architecture: BIPV products such as photovoltaic tiles and photovoltaic curtain walls will change the traditional appearance of buildings and achieve a perfect integration of photovoltaics and architecture.
(4) Smart microgrid: Multiple household photovoltaic systems can form a community microgrid, improving local energy self-sufficiency and power supply reliability.
(5) Green financial support: Financial innovations such as photovoltaic leasing and green bonds will lower investment barriers and accelerate market penetration.
5.3 Long term Development Outlook
Looking ahead to the next 10-20 years, home photovoltaics will play a greater role in the following areas:
(1) Becoming an important component of the power system: With increasing penetration, household photovoltaics will shift from; Supplementary Energy "; Transforming into '; Main Energy "; one of.
(2) Promoting energy democratization: enabling ordinary households to directly participate in energy production and trading, reshaping the energy value chain.
(3) Promoting rural electrification: In areas with insufficient power grid coverage, off grid photovoltaic systems will become an important power solution.
(4) Drive the development of related industries: from photovoltaic manufacturing to installation services, to energy storage, intelligent control, etc., forming a complete industrial chain.
The International Renewable Energy Agency (IRENA) predicts that by 2050, photovoltaic power generation will account for over 25% of global electricity supply, with a significant proportion coming from distributed home photovoltaic systems.
Conclusion: Moving towards a new era of household energy
As the core driving force for household energy security, photovoltaic systems are leading a profound energy consumption revolution. It has not only changed the way households obtain energy, but also reshaped people's understanding of energy - transforming it from a simple consumer good to a producible and manageable resource. With technological advancements, cost reductions, and policy support, photovoltaic systems are transitioning from; Optional "; Becoming '; Required "; From '; Luxury goods; Becoming '; Essential goods;.
The significance of this transformation goes far beyond the economic level. It represents a shift towards a sustainable lifestyle for humanity and is an important way to address climate change and ensure energy security. For every family, investing in photovoltaics is not only a financial decision, but also a responsible choice for the future. With '; Photovoltaic+; With the continuous innovation of models, we have reason to believe that a new era of clean, efficient, and intelligent home energy is coming.
