How to improve your own rooftop photovoltaic power generation efficiency?

How to improve your own rooftop photovoltaic power generation efficiency

Not all solar power plants have the same power generation efficiency. How can photovoltaic power plants improve power generation efficiency? In addition to factors such as the amount of solar radiation and the angle of inclination of photovoltaic modules, what are the influencing factors? Let’s take a look at it.

Solar radiation

When the conversion efficiency of the photovoltaic cell module is constant, the amount of power generated by the photovoltaic system is determined by the intensity of the solar radiation. Under normal circumstances, the utilization efficiency of photovoltaic system for solar radiation is only about 10%. So take into account solar radiation intensity, spectral characteristics, and climate.

The tilt angle of photovoltaic modules

The azimuth of the PV module is generally selected in the south direction to maximize the power generation per unit capacity of the PV power plant. As long as it is within ±20° of the south direction, it will not have much influence on the amount of power generation. If possible, it should be as far as 20°to the southwest.

PV module efficiency and quality

Calculation formula: theoretical power generation = annual average solar radiation total * total solar cell area * photoelectric conversion efficiency, there are two factors of the solar cell area and photoelectric conversion efficiency, the conversion efficiency has a direct impact on the power generation capacity of the power station.

Component matching loss

In the case of series connection, current loss due to the component current difference, any parallel connection will result in voltage loss due to the component voltage difference. The loss may reach more than 8%. In order to reduce the loss of matching loss and increase the power generation capacity of the power station, we must pay attention to the following aspects: 1. Reduce the matching loss, try to use the series of components with the consistent current; 2. The attenuation of the components should be as consistent as possible; 3. Isolation diode.

Temperature (ventilation)

Data show that the temperature rises by 1°C, the maximum output power of crystalline silicon PV modules drops by 0.04%. Therefore, it is necessary to avoid the influence of temperature on power generation and maintain good ventilation conditions.

The effect of dust can not be underestimated

The panel of the crystalline silicon component is tempered glass, which is exposed to the air for a long time, and naturally, there is organic matter and a large amount of dust accumulation. The surface ash blocks the light, which reduces the output efficiency of the module and directly affects the amount of power generated. It can also cause the component “hot spot” effects that can cause component damage.

Shadow and snow cover

In the process of site selection of photovoltaic power plants, it is necessary to pay attention to the shielding of light. Avoid areas that may be obscured by light. According to the circuit principle, when the components are connected in series, the current is determined by the least one block, so if there is a shadow, it will affect the power generation of this component. Similarly, the snow in winter should be removed in time.

Maximum Output Power Tracking (MPPT)

MPPT efficiency is a key factor in determining the amount of PV inverter power generation, and its importance far exceeds the efficiency of the PV inverter itself. MPPT efficiency is equal to hardware efficiency multiplied by software efficiency. The hardware efficiency is mainly determined by the accuracy of the current sensor and the accuracy of the sampling circuit; the software efficiency is determined by the sampling frequency. There are many ways to implement MPPT, but no matter which method is used, the power of the component is measured first, and then the change is reacted. The key component of this is the current sensor. Its accuracy and linearity directly determine the hard efficiency, and the sampling frequency of the software is also determined by the accuracy of the hardware.

Reduce line loss

In the photovoltaic system, the cable accounts for a small part, but the influence of the cable on the power generation cannot be ignored. It is recommended that the line loss of the DC and AC circuits of the system be controlled within 5%. The cables in the system should be well prepared, the insulation performance of the cable, the heat and flame resistance of the cable, the moisture and light resistance of the cable, the type of cable core, and the size of the cable. All these factors should be carefully considered.

Inverter efficiency

The photovoltaic inverter is the main component and an important component of the photovoltaic system. In order to ensure the normal operation of the power station, it is particularly important to select the correct configuration of the inverter. In addition to the technical specifications of the entire photovoltaic power generation system and reference to the product sample manual provided by the manufacturer, the following technical indicators should be considered: 1. Rated output power; 2. Output voltage adjustment performance; 3. Overall efficiency; 4. Starting performance.

What Should You Pay Attention To When Cleaning Solar Modules?

What Should You Pay Attention To When Cleaning Solar Modules

For long-term use of solar panels, the surface of the photovoltaic panels is covered with too much dust, and if we do not pay attention to cleaning, it will seriously affect the power generation efficiency, so cleaning is very important, and it should be cleaned regularly to improve power generation efficiency. When we clean the solar panels, we need to pay attention to a few things.

  1. In order to avoid the electric shock damage to the human body and the damage to the components under high temperature and strong light, the staff generally choose to clean the components in the morning or late in the afternoon.
  2. Before cleaning the components, check whether there is any abnormality in the output of the monitoring records, and check the connection wires and related components for damage and adhesion. It is necessary to test the aluminum frame, the bracket and the tempered glass surface of the assembly with a test pencil. In order to eliminate potential leakage, to ensure personal safety.
  3. Solar PV module aluminum frame and photovoltaic bracket have many sharp corners. Therefore, personnel who perform component cleaning should wear appropriate overalls and wear a hat to avoid injury and injury. Hooks, straps, thread ends which are prone to tie should be prohibited on clothing or tools.
  4. It is forbidden to step on the solar system such as solar panel, rail bracket, cable tray or other means to leverage component boards and brackets.
  5. It is strictly forbidden to clean the solar modules under meteorological conditions such as heavy wind, heavy rain, thunderstorm or heavy snow. Winter cleaning should be avoided to prevent the temperature from falling too low and freezing, causing dirt to accumulate. For the same reason, do not rinse with cold water when the solar panel is very hot.
  6. It is forbidden to wipe the solar module with hard and sharp tools or corrosive solvents and alkaline organic solvents. Also not allowed to spray the cleaning water to the component such as the junction box, cable tray, combiner box and other equipment. The impact pressure of the cleaning equipment on the components during cleaning must be controlled within a certain range to avoid cracking due to improper force.
  7. When cleaning personnel, it is forbidden to stand at a position less than 1 meter from the edge of the roof. It is not allowed to throw tools and debris down and take them away after the operation is completed.

Finally, users are not advised to clean themselves without knowing the relevant professional cleaning knowledge. It is best to have professional solar cleaning personnel to carry out cleaning and maintenance to better ensure that the solar modules are not damaged during the cleaning process.

Technical Advantages Of Solar Street Lights

solar-street-light

1.Easy installation: When installing solar street lights, there is no need to set up complex lines, just make a cement base, make a battery pit, and fix it with galvanized bolts. It does not need to consume a lot of manpower, material resources and financial resources. The installation is simple, there is no need to wire or “open the belly” to dig the ground construction, and there is no power outage and power limitation.

2.Less investment: solar energy street lamps will be invested once and benefit in the long run. Because the lines are simple, no maintenance costs will be incurred and no expensive electricity charges will be generated. 6-7 years to recover the cost, 3-4 years to save more than 1 million electricity and maintenance costs. The circuit lamp can be omitted, the electricity cost is high, the line is complicated, and the line needs to be repaired for a long time without interruption. In the case of special voltage instability, the sodium lamp is easy to be damaged, and as the age increases, the line aging and maintenance costs are increasing year by year.

3.Good safety performance: Due to the low voltage of 12-24V, the solar street lamp has stable voltage, reliable operation and no hidden dangers. It is an ideal product for the ecological community and the road administration department. There are no accidents such as electric shock or fire. The safety of the circuit lights in the city is great. People’s living environment is constantly changing. Road reconstruction, landscape engineering construction, the power supply is not normal, and cross-construction of water gas pipelines brings many hidden dangers.

4.Energy saving and environmental protection: The solar energy photoelectric conversion provides electricity, which is inexhaustible. No pollution, no noise, no radiation. Solar street lights can add new selling points for the development and promotion of noble ecological communities, sustainable reduction of property management costs and reduction of the cost of the public share of the owners. In summary, the inherent characteristics of solar lighting safety without hidden dangers, energy saving without consumption, green environmental protection, easy installation, automatic control and maintenance-free will directly bring obvious advantages for the sale of real estate and the construction of municipal engineering.

5.Long service life: The life of solar lamps is much higher than that of ordinary electric lamps. For example, the main components of solar lamps—the average life of solar modules is 25 years, low-pressure sodium lamps are 18,000 hours, basic energy-saving lamps is 6000 hours, super-bright LEDs is more than 50,000 hours, the life of solar-powered batteries is 2-5 years below 38AH, 3-7 years of 38-150AH.

In short, the comprehensive comparison of the characteristics of solar lamps to save investment is quite obvious.

How To Build Up A Small Home Solar Power System?

Small home solar power generation systems

Small home solar power generation systems are divided into off-grid power generation systems and on-grid power system. The main difference is whether there is a battery.

System Overview

  1. Applicable environment: in the wild, large and medium-sized residential / houses that are difficult in taking electricity (it is not recommended to install in the mains area, or install the mains complementary type).
  2. The system is equipped with high-quality monocrystal silicon or polycrystalline silicon solar panels and has a supporting maintenance-free solar battery, photovoltaic off-grid inverter and charge controller with overcharge and over-discharge protection function, which can be designed as mains / intelligent switching function of the photovoltaic system. The controller adopts LCD screen/indicator display, which is beautiful in appearance, safe and efficient.
  3. Easy maintenance, a long service life of more than 20 years, a variety of charging methods complementary, solar and city power can charge the system.

Composition

The small household solar power system is composed of a solar panel, a solar controller, and a battery bank. If the output power is AC 220V or 110V, you need to configure an inverter. All these components you can find it in Eco-Sources solar products at competitive price.

Solar Panels

The function of the solar panel is to convert the light energy of the sun into electrical energy, and the output DC power is stored in the battery. Solar panels are one of the most important components in small-scale home solar power generation systems. Their conversion rate and service life are important factors that determine whether solar cells have value in use. It is made up of the following materials:

  1. Solar Cells: High-efficiency (16.5% or more) monocrystalline or polycrystalline silicon solar cells are used to ensure that the solar panel generates sufficient power.
  2. Glass: Low-iron tempered suede glass (also known as white glass) with a thickness of 3.2 mm and a transmittance of over 91% in the wavelength range (320-1100 nm) of the solar cell’s spectral response. For infrared light greater than 1200 nm, there is a higher reflectivity. The glass is also resistant to solar ultraviolet radiation and the light transmittance does not decrease.
  3. EVA: A high-quality EVA film with a thickness of 0.78 mm, which is coated with an anti-UV agent, an antioxidant and a curing agent, is used as a sealing agent for solar cells and a connecting agent with glass and TPT. It has a high light transmittance and anti-aging ability.
  4. TPT: The back cover of the solar cell-the fluoroplastic film is white, reflecting the sunlight, so the efficiency of the component is slightly improved, and because of its high infrared emissivity, the operating temperature of the component can also be lowered. Which helps improve the efficiency of components.
  5. Border: The aluminum alloy frame used has high strength and strong resistance to mechanical shock.

Solar Charge Controller

  1. Using a single-chip computer and special software to achieve intelligent control.
  2. Accurate discharge control using battery discharge rate characteristics correction. The discharge end voltage is a control point corrected by the discharge rate curve, which eliminates the inaccuracy of the simple voltage control over discharge and conforms to the inherent characteristics of the battery, it means different discharge rates have different final voltages.
  3. With overcharge, over discharge, electronic short circuit, overload protection, unique anti-reverse protection and other automatic control; the above protection does not damage any parts, do not burn insurance。
  4. The series PWM charging main circuit is adopted, so that the voltage loss of the charging circuit is reduced by nearly half compared with the charging circuit using the diode, and the charging efficiency is 3%-6% higher than the non-PWM, which increases the power consumption time. Overcharged recovery charging, normal direct charge, and floating charge automatic control mode make the system have a longer service life. At the same time, it has a high precision temperature compensation.
  5. The intuitive LED lighting tube indicates the current battery status, allowing the user to understand the usage status.
  6. All control uses industrial grade chips, which can run freely in cold, high temperature and humid environments. At the same time, the crystal timing control is used to ensure accurate control.
  7. Using digital LED display and settings, a one-button operation can complete all settings, the use of extremely convenient and intuitive role is to control the working state of the entire system, and the battery has overcharge protection, over-discharge protection. In places with large temperature differences, qualified controllers should also have temperature compensation. Other additional functions such as light control switches and time control switches should be optional for the controller.

Solar Battery

The function of the battery is to store the electrical energy emitted by the solar panel when it is exposed to light and release it when needed. The solar battery is the application of ‘battery’ in solar photovoltaic power generation. Currently, there are four kinds of lead-acid maintenance-free batteries, ordinary lead-acid batteries, colloidal batteries and alkaline nickel-cadmium batteries, and the widely used batteries are lead-acid maintenance-free batteries and gel batteries. These two types of batteries are suitable for solar power systems, especially unattended workstations, because of their inherent ‘free’ maintenance characteristics and less environmental pollution.

Solar Inverter

The direct output of solar energy is generally DC 12V, 24V, 48V. In order to supply electrical energy to 220V AC appliances, it is necessary to convert the DC power generated by the small household solar power system into AC power, thus requiring the use of a DC-AC inverter.

Advantages Of A Small Home Solar Power System

  1. Safe and reliable, no noise, no radiation, no need to consume fuel, no mechanical rotating parts, low failure rate and long service life.
  2. It is environmentally friendly, not limited by geographical location, short construction period, random size, easy assembly and disassembly, easy to move.
  3. The cost of disassembly and assembly is low, and it can be easily combined with buildings. There is no need to pre-embed high transmission lines, which can avoid damage to vegetation and environment when laying cables over long distances.
  4. The voltage is stable, and it is widely used in various electrical equipment. It is very suitable for electricity use in remote places such as villages, farms, hills, islands, highways, etc. It is also an excellent emergency backup power source.

Design Considerations For Small Home Solar Power Systems

  1. Where is the small household solar power system used?
  2. What is the radiation situation in the area?
  3. What is the load power of the system?
  4. What is the output voltage of the system, DC or AC?
  5. How many hours does the system need to work every day?
  6. How many days does the system need to be powered continuously in the event of rainy weather without sunlight?
  7. What is the starting current?
  8. The number of system requirements.

The Classification And Structure Composition Of Solar Panels

Solar panels are assembled from solar cells. According to the type of solar cell, it can be mainly divided into two types
1. Crystalline Solar Panel, which is assembled from polysilicon solar cells of monocrystalline solar cells.
2. Amorphous Solar Panel, which is assembled from thin-film solar cells or organic solar cells.

The feature of solar cells

(1) Monocrystalline silicon solar cells

The photoelectric conversion efficiency of monocrystalline silicon solar cells is about 15%-24%. This is the highest photoelectric conversion efficiency among all kinds of solar cells, but the production cost is so great that it cannot be widely used. As monocrystalline silicon is generally encapsulated with tempered glass and waterproof resin, it is rugged and durable, with a typical life up to 15-25 years.

(2) Polycrystalline silicon solar cells

The manufacturing process of polycrystalline silicon solar cells is similar to that of monocrystalline solar cells, but the photoelectric conversion efficiency of polycrystalline solar cells is reduced a lot, and its photoelectric conversion efficiency is about 12%. Because of its simple material manufacturing, saving power, making the total production cost low, so it has been greatly developed. In addition, the service life of polysilicon solar cells is also shorter than monocrystalline solar cells. In terms of performance, mono solar cells will be slightly better.

(3) Amorphous silicon solar cells
Amorphous silicon solar cell is a new type of thin-film solar cell that appeared in 1976. It is completely different from the monocrystalline silicon and polycrystalline silicon solar cell production methods, the process is greatly simplified, the silicon material is consumed less, the power consumption is lower, and its main advantage is that it can generate electricity in low light conditions. However, the main problem of amorphous silicon solar cells is the low photoelectric conversion efficiency. The international advanced level is about 10%, and it is not stable enough. With the extension of time, its conversion efficiency is attenuated.

Structure Composition

The structure of solar panel

(1)  Tempered Glass

Its role is to protect the main body of power generation (such as solar cells), the transmittance of tempered glass must be high, generally to reach more than 91%, and it need to be ultra-white tempered.

(2) EVA (ethylene vinyl acetate) Film

In the solar industry, the most common encapsulation is with cross-linkable ethylene vinyl acetate (EVA). With the help of a lamination machine, the cells are laminated between films of EVA in a vacuum, which is under compression.
The material of the transparent EVA directly affects the life of the components. EVA exposed to the air is susceptible to aging and yellowing, which affects the light transmittance and the power generation quality of the module. In addition to the quality of EVA itself, the laminating process of component manufacturers is also an important factor. For example, EVA adhesiveness is not up to standard, EVA and tempered glass, backsheet adhesive strength is not enough, it will all cause premature aging of EVA and affect the life of the components.

(3) Solar Cells

The mainstream solar cells in the market are crystalline silicon solar cells and thin-film solar cells. Both have their advantages and disadvantages. The production equipment of crystalline silicon solar cells costs are relatively low, the material consumption is so large that the cost of the solar cell is high, but its photoelectric conversion efficiency is also high. The production cost of thin-film solar cells is low, but its photoelectric conversion efficiency is not high. Its advantage is that it has a good power generation effect in weak light, and it can also generate electricity under ordinary lighting, such as solar cells on calculators.

(4) Back Sheet

The main function of the back sheet is sealing, insulation, and waterproofing. It generally used TPT, TPE and other materials which must be resistant to aging, most of the components manufacturers are 25 years warranty, tempered glass and aluminum alloy frame are generally no problem, the key is with the back sheet and silicone can meet the requirements.

(5) Aluminum Alloy Frame

Its role is to protect the laminate and play a certain role in sealing and supporting.

(6) Junction Box

The entire power generation system is protected and functions as a current transfer station. If a component is short-circuited, the junction box automatically disconnects the short-circuited solar cell string to prevent the entire system from being burned. The most critical part of the junction box is the selection of the diode. According to the type of solar cell in the module, the corresponding diode is not the same.

(7) Silica Gel

Sealing function, used to seal components and aluminum alloy frame, back sheet, junction box at the junction, the process is simple, convenient, easy to operate, and the cost is very low.

Daily Maintenance And Inspection Considerations Of Solar Panels

Daily Maintenanc Of Solar Panels

Some users have installed solar street lights or solar array power systems so that they can use them once and for all. However, the discovery of electricity for a long time is also less and less, and the lights are not bright enough, but we do not know how to do it.

Of course, In addition to the quality of the product itself and the installation problems, the main reason is that there is too much dust on the solar panel or covered by snow in winter, the photoelectric conversion rate drops, the charging is insufficient, and the battery power is insufficient.

Therefore, after the installation of solar power system, we should regularly organize personnel to carry out all-round and meticulous inspection of all the panels. This is to ensure that the panels will operate under good conditions for a long time, so as to create more economic benefits.

Eco-Sources has collected and organized some notes on the daily maintenance and inspection of solar panels. Whether it is for individual users or home users, We hope to help everyone in the use of solar panels.

  1. Check whether the solar panel is damaged, so that it can be discovered in time and replaced in time.
  2. Check whether the solar panel connection cable and the ground cable are in good contact with each other.
  3. Check if there is a fever in the junction box.
  4. Check if the solar panel brackets are loose or fracture.
  5. Check and clean the cover around the panel.
  6. Check if there is any animal destroy the solar panel.
  7. Check if there is bird dropping on the surface of the panel, and clean it in time.
  8. On snowy days, the solar panels should be cleaned up in time to avoid the snow and ice on the surface.
  9. On rainy days, we should check if all the waterproof seal is good, with or without water leakage.
  10. Test the temperature of the solar panel, analyze it against the ambient temperature.

If you have more experience, welcome to add…