How Solar Panels Work: The Plain-English Guide

A solar panel has no moving parts. It contains no fuel. When sunlight hits it, electrons in the silicon cells start moving, and that movement is electricity. Every panel on every roof in Singapore produces power through the same mechanism discovered in 1954 at Bell Labs, the photovoltaic effect. Understanding how it works takes about five minutes and removes every conceptual uncertainty you might have before investing in a system.

The Signal: What Happens Inside a Solar Panel

A solar panel is made of photovoltaic cells, thin wafers of silicon treated to have a positive layer and a negative layer. When photons from sunlight hit the silicon, they knock electrons loose from their atoms. The electric field built into the cell pushes those electrons in one direction, creating a flow of electrons. Flow of electrons is electricity. More light means more electrons moving means more electricity.

This current flows out of the panel as direct current, the same type of current a battery produces. The sun does not turn the electricity on and off. As long as light is hitting the panel, electrons are moving. Clouds reduce the light intensity, so generation drops, but does not stop. Even on an overcast Singapore day, diffuse light still produces roughly 20 to 40% of peak output.

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The Ripple: From Panel to Power Point

Your appliances run on alternating current, the electricity that comes from the SP Group grid through your wall sockets. A solar panel produces direct current. These two types of electricity are not directly compatible, which is where the inverter comes in.

The inverter is a box typically mounted on an interior wall near your electrical board. It takes the DC electricity from your panels, converts it to AC at exactly the right voltage and frequency to match the grid, and feeds that power into your home's circuits. When the solar system is producing more power than your home is using, the excess flows automatically through your meter and onto the SP Group grid. SP Group credits you at the Solar Crediting Tariff of S$0.2581/kWh under the Enhanced Central Intermediary Scheme. When the system is producing less than you need, the grid supplies the rest seamlessly. No switch to flip. No manual intervention.

At night, when the panels produce nothing, your home runs entirely on grid power as normal. A standard grid-tied solar system in Singapore has no battery, it does not need one to function, because the grid acts as an effectively infinite battery that absorbs your excess and supplies your shortfall. Battery storage is an optional addition that shifts some of that grid interaction but does not change the fundamental flow described above.

Singapore's Geographic Advantage

At latitude 1.3° North, Singapore sits near the equator. This has two practical effects. First, the sun is consistently high in the sky year-round, which maximises the direct beam irradiance hitting a roof-mounted panel. Second, there is no winter. European solar markets, including Germany, the world's largest installed base, see enormous generation swings between summer and winter. A German system might produce four times as much electricity in June as in December. A Singapore system produces almost the same every month of the year.

Singapore's annual solar resource is approximately 4.33 peak sun hours per day, a measure of daily energy, not literal hours of sunlight. This gives Singapore's landed homeowners roughly 30% more solar generation per panel than a comparable German installation, despite the common perception that a tropical country prone to afternoon thunderstorms must have poor solar conditions. Cloud cover and monsoon rainfall reduce peak intensity on some days, but those effects are already averaged into the 4.33 PSH figure derived from decades of meteorological data.

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Singapore has no winter. That single geographic fact is worth roughly S$500 more per year in solar savings compared to a system the same size installed in Munich — every year, for 25 years.

When your system is commissioned and the bi-directional meter is installed by SP Group, you do not need to change anything in your home. Every wall socket works exactly as before. The only difference is that some of the electricity those sockets deliver has come from your roof rather than a gas plant, and your quarterly SP bill will be noticeably lower. See how much lower for your home here.

Further reading: IRENA solar power fundamentals · IEA photovoltaics report.