Solar PV for Homes

Solar Panels

Solar PV (photovoltaic) panels work by converting sunlight directly into electricity through the photovoltaic effect.

1. Light Absorption:
   • Photon Interaction: When sunlight (composed of photons) hits the surface of a solar panel, the photons are absorbed by the semiconductor material in the solar cells (usually silicon).
   • Energy Transfer: The energy from the photons is transferred to the electrons in the semiconductor material.
2. Creation of Electron-Hole Pairs:
   • Electron Excitation: The energy absorbed from the photons excites the electrons, causing them to break free from their atoms. This creates electron-hole pairs.
   • Electric Field: Solar cells are designed with a built-in electric field due to the junction of two types of silicon (n-type and p-type). This field helps in the separation of electrons and holes.
3. Flow of Electric Current:
   • Movement of Electrons: The freed electrons are driven by the electric field toward the n-type layer, while the holes move toward the p-type layer.
   • Circuit Creation: When an external circuit is connected, the electrons flow through this circuit to recombine with the holes, creating an electric current.
4. Energy Conversion:
   • Direct Current (DC) Output: The flow of electrons through the external circuit produces direct current (DC) electricity.
   • Inverter Usage: This DC electricity is often converted to alternating current (AC) using an inverter, as AC is the standard form of electricity used in homes and businesses.

Efficiency and Optimization

• Anti-Reflective Coatings: Solar cells often have anti-reflective coatings to maximize the absorption of sunlight.
• Orientation and Tilt: Solar panels are installed at specific angles and orientations to maximize exposure to sunlight throughout the day.
• Temperature and Shading: Efficiency can be affected by temperature and shading; panels perform better at lower temperatures and without obstructions blocking sunlight.

Energy Utilization

• On-site Consumption: The generated electricity can be used immediately to power appliances and devices.
• Grid Integration: Excess electricity can be fed back into the grid (for grid-tied systems), often allowing the owner to receive credit or payment from the utility company.
• Battery Storage: In off-grid or hybrid systems, surplus energy can be stored in batteries for use when sunlight is not available.

Summary

Solar PV panels harness sunlight to generate electricity through a series of steps involving photon absorption, electron excitation, and current flow. By converting solar energy into usable electric power, these panels provide a renewable, clean, and sustainable energy solution.

Inverters

Solar PV (photovoltaic) inverter is a crucial component in a solar power system. It converts the direct current (DC) electricity generated by solar panels into alternating current (AC) electricity, which is the standard form of electricity used in homes and businesses.

Role of a Solar PV Inverter

1. DC to AC Conversion: Solar panels generate DC electricity, but most household appliances and the electrical grid operate on AC electricity. The inverter changes the DC output into AC, making it compatible with standard electrical systems.
2. Grid Interaction: For grid-tied systems, the inverter synchronizes the AC electricity with the grid’s voltage and frequency, allowing excess power to be fed into the grid.
3. System Monitoring: Many inverters come with monitoring capabilities, providing data on power production, system performance, and potential issues.
4. Safety Functions: Inverters include safety features such as anti-islanding protection, which prevents the inverter from feeding power into the grid during a power outage, protecting utility workers.

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Types of Solar PV Inverters

1. String Inverters:
   • Description: Connects a series (or “string”) of solar panels to a single inverter.
   • Usage: Common in residential and small commercial installations.
   • Advantages: Cost-effective and simpler installation.
   • Disadvantages: Performance can be affected by shading or malfunctioning of a single panel.
2. Microinverters:
   • Description: Each solar panel has its own small inverter.
   • Usage: Often used in residential systems with shading issues or complex roof structures.
   • Advantages: Optimizes the performance of each panel independently, improving overall system efficiency and reliability.
   • Disadvantages: Higher initial cost and more complex installation.
3. Power Optimizers:
   • Description: Devices attached to each solar panel to optimize its output, used in conjunction with a string inverter.
   • Usage: Similar applications as microinverters but with a centralized inverter.
   • Advantages: Improves system performance and mitigates shading issues while maintaining some cost advantages of string inverters.
   • Disadvantages: Requires additional components compared to traditional string inverters.
4. Hybrid Inverters:
   • Description: Combines functions of a solar inverter with battery management capabilities.
   • Usage: Suitable for systems with energy storage (batteries).
   • Advantages: Manages solar power, battery storage, and grid connection seamlessly.
   • Disadvantages: More expensive than standard inverters.

Key Functions of a Solar PV Inverter

1. MPPT (Maximum Power Point Tracking): Ensures that the solar panels operate at their maximum power output by constantly adjusting the electrical operating point.
2. Grid Synchronization: Matches the phase, frequency, and voltage of the output AC power to the grid.
3. Efficiency Optimization: Enhances the overall efficiency of the solar power system by reducing energy losses during the conversion process.
4. Safety and Protection: Includes features like ground fault protection, over-voltage protection, and anti-islanding to ensure safe operation.
5. Monitoring and Reporting: Provides real-time data on energy production, performance metrics, and diagnostic information.

Summary

A solar PV inverter is essential for converting the DC electricity generated by solar panels into AC electricity suitable for use in homes and businesses. It plays a critical role in ensuring the efficient and safe operation of a solar power system, offering various functionalities and types to suit different installation needs and conditions.

Solar PV panels are well worth considering if you have a mainly south-facing roof with little or no shade.

The maximum power output from solar panels will be achieved for a south-facing roof with a tilt angle of between 30° and 45° with no shade.

Although a south-facing roof would yield the best power output, a south-west or south-east-facing roof would also be beneficial. Solar panels work on both sunny and overcast days. Most roofs are suitable for solar panels regardless of pitch, velux windows or chimneys.

Planning permission is generally not required for domestic solar panels. Exceptions apply for listed buildings and buildings in conservation areas.

The Met Office website has useful radiation maps. The higher the radiation figure, the more electricity your PV system will produce.

Whether or not we’ve installed your Solar PV system, they do require maintenance, albeit minimal. If the panels are kept relatively clean and are not overshadowed by larger trees or other unforeseen obstructions your panels will work at their optimum capacity.

In the UK panels that are tilted at 15° or more have the additional benefit of being cleaned by rainfall to ensure optimal performance. Debris is more likely to accumulate if you have ground mounted panels. If dust, debris, snow or bird droppings are a problem they should be removed with warm water.

However we would recommend that a system health check is carried out every 3 years as systems that are not inspected over this time period could be up to 30% less efficient than when they are new.

Our Solar PV Maintenance packages will ensure that your system is safe and preforming to its full capability.