How Do Solar Panels Work
|Keegan Woolgar
Quick Answer: The functioning of solar panels relies on the photovoltaic (PV) effect. When photons from sunlight come into contact with the semiconductor material in a solar cell, typically silicon, they displace electrons, resulting in a flow of direct current (DC) electricity. These solar cells are grouped together to form a solar panel, and several panels are connected to create an array. A solar inverter is responsible for converting the DC output into alternating current (AC), which can then be utilized to power household devices, stored in batteries, or fed into the electricity grid.
Comprehending how solar panels function allows you to make wiser decisions regarding system selection, quote evaluation, and optimising your investment. If you want a broader overview of solar energy systems in South Africa, read our guide on Solar Panels in South Africa: Everything You Need to Know. Below is a comprehensive, guide that outlines the entire proces, from sunlight reaching the panel to the point where it powers your lights and appliances.
What are solar panels made of?
A solar panel consists of a multi-layered structure, with each layer designed for a specific purpose:
- Solar cells — This is the active layer, usually composed of either monocrystalline or polycrystalline silicon. Each solar cell is a thin wafer, approximately 180–200 microns thick, that produces electricity when exposed to light. A typical panel is made up of 60, 72, or 108 interconnected cells.
- Tempered glass — The front of the panel is shielded by low-iron tempered glass (3–4mm thick), which allows more than 90% of incoming light to pass through while safeguarding the cells from hail, debris, and UV damage.
- EVA encapsulant — Ethylene vinyl acetate film is layered above and below the solar cells, effectively bonding the components together while offering electrical insulation and protection against moisture.
- Backsheet — This is a polymer film located at the back of the panel, serving as a final defense against moisture, electrical shorts, and UV exposure. For all-black panels, the backsheet is black instead of white.
- Aluminium frame — An anodised aluminium frame encircles the laminate, providing structural strength and attachment points for the mounting system. In coastal areas like Durban and KZN, marine-grade anodised aluminium is crucial for resisting corrosion from salt air.
- Junction box — Located on the rear of the panel, this small weatherproof enclosure contains the bypass diodes and the MC4 connector terminals where the DC cables are connected.
Step 1: How sunlight creates electricity in a solar cell
A solar panel comprises numerous individual solar cells, usually containing 60, 72, or 108 cells per panel. Each cell is constructed from two layers of silicon: one positively charged (P-type) layer and one negatively charged (N-type) layer, which together form a P-N junction. When sunlight, in the form of photons, hits the solar cell, it dislodges electrons from the silicon atoms. The electric field generated at the P-N junction directs these free electrons in a uniform direction, resulting in an electric current. This phenomenon is known as the photovoltaic effect, which was first identified in 1839 by the French physicist Edmond Becquerel.
Step 2: How solar panels generate DC electricity
The movement of electrons within the circuit creates direct current (DC) electricity. Each cell generates a modest voltage of approximately 0.5V, which is why they are connected in series within the panel to achieve a usable voltage, usually ranging from 30V to 50V per panel under standard conditions. Subsequently, multiple panels are interconnected to form an array. In a standard residential installation in South Africa, panels can be arranged in series to boost voltage or in parallel to enhance current, based on the specifications of the inverter.
Step 3: How a solar inverter converts DC to AC power
The majority of residences and commercial establishments operate on alternating current (AC) within the range of 220–240V. Solar inverters play a crucial role by converting the direct current (DC) generated by solar panels into usable AC power through a method known as inversion. Additionally, modern hybrid inverters are designed to oversee the charging and discharging of battery storage, as well as the import and export of electricity to and from the municipal grid. EagleEyeSolutions matches each residential and commercial solar installation in Durban and KZN to the appropriate inverter technology — from simple string inverters for grid-tied systems to sophisticated hybrid inverters that simultaneously manage solar energy, battery storage, and grid connections.
Step 4: How solar power is used, stored, or fed back to the grid
Once the electricity is converted to AC, it moves to your distribution board and is used to power your appliances, just like grid electricity. Any surplus electricity generated by your panels that exceeds your immediate needs can be:
• Stored in a battery bank for future use (such as overnight or during loadshedding)
• Exported to the municipal grid under an SSEG agreement (if applicable in eThekwini)
• Curtailed (wasted) if neither storage nor grid export options are available
Implementing a battery backup system is the most efficient method to ensure that excess solar energy produced during the day is not wasted, allowing your home or business to stay powered during loadshedding.
How solar panels perform in KZN's climate
In KwaZulu-Natal, the solar irradiance is excellent, typically falling between 4.5 and 5.5 peak sun hours per day along the coastal areas. However, the coastal environment poses specific challenges that can affect the performance of solar panels and dictate their installation methods:
| KZN Factor | Impact on Installation |
|---|---|
| Salt air corrosion | Requires marine-grade anodised aluminium orstainless steel mounting hardware |
| High humidity | Affects inverter and battery ventilationrequirements |
| Coastal cloud cover | Morning cloud on the Berea can reduce morningoutput; panels perform best from mid-morning onwards |
| High UV intensity | KZN's latitude means panels receive intense UVyear-round; high-efficiency monocrystalline panels perform best |
| Heat | All solar panels lose efficiency in high heat;panels with low temperature coefficients perform better on hot KZN days |
Understanding how your panels perform in KZN conditions is the first step - for a complete breakdown of what a residential system involves, how many panels your home needs, and what the installation process looks like, see our guide to residential solar panels for South African homeowners.
Why heat reduces solar panel output
Solar panels are tested and rated under Standard Test Conditions (STC): 25°C cell temperature, 1,000 W/m² irradiance, and a specific air mass value. In practice, panel surface temperatures in KZN often reach 50–70°C on summer afternoons - well above the STC reference. Every solar panel has a temperature coefficient for power (Pmax), expressed as a percentage loss per degree Celsius above 25°C. A typical monocrystalline panel carries a coefficient of approximately −0.35% per °C. At a cell temperature of 65°C (40°C above STC), that panel is operating at roughly 86% of its rated output - a 14% reduction simply from heat. This is why panel selection matters in KZN's climate. Premium monocrystalline panels from manufacturers such as LONGi, JA Solar, and Canadian Solar carry lower temperature coefficients (−0.26% to −0.32% per °C) than standard polycrystalline panels, which typically run at −0.40% to −0.45% per °C. Over a 25-year system life, this difference in heat performance has a measurable impact on total energy yield.
How to connect solar panels to an inverter
Solar panels are linked to the inverter via DC cables and connectors, with MC4 connectors being the most widely used standard in photovoltaic systems. The connection process involves the following steps:
• The panels are arranged in series or parallel strings based on the inverter's MPPT (Maximum Power Point Tracking) input requirements.
• String cables extend from the solar array to the DC isolator switch.
• The DC isolator is then connected to the inverter's DC input terminals.
• The inverter's AC output is linked to the distribution board.
• A generation meter, which is necessary for SSEG grid connection, is placed between the inverter and the distribution board.
Frequently asked questions
Do solar panels work on cloudy days?
Certainly, solar panels can create electricity from diffuse light, not solely from direct sunlight. On cloudy days in Durban, the output of these panels generally ranges from 20% to 50% of their rated capacity, depending on how thick the cloud cover is. They are unable to generate power after sunset.
Do solar panels work during loadshedding?
Battery storage is essential. A grid-tied system without battery storage will automatically shut down during loadshedding for safety, ensuring the protection of grid workers. In contrast, a hybrid system equipped with battery storage can keep your home powered during an outage by seamlessly switching to battery supply.
How do solar panels connect in series versus parallel?
Linking panels in series raises the voltage while maintaining the same current. On the other hand, connecting them in parallel preserves the voltage but boosts the current. The majority of contemporary hybrid inverters utilise MPPT charge controllers that can handle a variety of string voltages. EagleEyeSolutions customizes each string configuration to optimise the efficiency of the particular inverter being installed.
How much electricity do solar panels produce per day?
The output is influenced by the wattage of the panel and the number of sun hours each day. For instance, a 400W panel located in KZN that gets 5 peak sun hours can generate about 2 kWh daily. In Durban, a standard 10-panel, 4 kW system would typically produce between 18 and 22 kWh each day during the summer months, while in winter, it would yield around 14 to 18 kWh.
How does a battery take over when the sun goes down?
When solar production drops below your home's demand, typically in the late afternoon - the hybrid inverter automatically begins drawing from the battery bank instead. This transition happens in milliseconds and is invisible to the occupants; lights, appliances, and devices continue running without interruption.
Ready to Install Solar Panels in KZN?
EagleEyeSolutions designs and installs solar PV systems matched to KZN's coastal climate - for both homes and businesses across Durban, Ballito, Westville, and the surrounding areas.