How Grid-Connect Solar Power Systems Work

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How Grid-Connect Solar Power Systems Work

Among the various solar power system options, the grid-connected solar power system emerges as both economical and uncomplicated. Also called a grid-tied solar system, this setup empowers you to generate electricity using solar panels and effortlessly channel any surplus energy back into the grid.

The cost of a grid-connected solar power system can range from $8,000 to $16,000 NZD, covering full installation.

What Is A Grid-Connected Solar Power System? - The Simple Explanation

At its core, a grid-connected solar power system comprises solar panels, usually positioned on a rooftop, alongside an inverter which transforms solar energy into usable household power. Additionally, the ensemble encompasses an array of components such as wiring, isolators, mounting, meters, and more, collectively referred to as the balance of system equipment.

This system is linked to the electrical grid (the poles and wires outside the home). This interconnection facilitates two functions:

  1. Excess solar energy can be fed back into the grid and sold to an energy retailer when household devices are inactive.
  2. The flexibility to draw power from the grid becomes available during periods when the solar system isn't actively generating energy, such as at night.

Video: How A Grid-Connected Solar Power System Works

The Step By Step Process Of How A Grid-Connected Solar Power System Works

How a grid connect solar power system works in New Zealand

  1. When sunlight hits solar photovoltaic (PV) panels, electricity (or solar energy) is produced.

  2. The electricity runs from solar panels through an inverter. The inverter turns the power from direct current (DC) into alternating current (AC), providing solar electricity to power electronic appliances in the home or office.

  3. As solar power is being produced during the day, and if appliances are in operation, solar power will run through a switchboard, thus powering appliances.

  4. Any appliance that is AC powered can use solar powered electricity; lights, dishwashers, electric hot water cylinders, to name but a few.

  5. If electrical appliances are switched off, or if excess solar power is being produced, the power gets sent to the grid and is measured by the meter box. Electricity retailers apply credits in exchange for energy produced. During the night, when solar power systems are not producing energy, power can be drawn from the grid. This can be paid for with credits earned.

Advantages Of Grid-Connected Solar Power Systems

Reduced Electricity Bills

The extent of your electricity expense reduction through solar power installation hinges on several variables. To illustrate, envision a 4kW system placed atop a 20-degree, north-facing roof of a residence in Invercargill. This system alone has the potential to slash over $1,000 from annual power expenditures.

Our solar calculator offers invaluable insights for a tailored estimate of potential savings on your electricity bills. Try it out here.

Key determinants of solar savings include:

  • Roof angle
  • Roof orientation
  • Geographical location (i.e. expected solar irradiance)
  • Effectiveness of solar system components and wiring

Protection Against Power Price Increases

Over the past 15 years, electricity prices have consistently surged by an average annual rate of 3%. By acquiring a solar power system, you proactively lock in your power costs for years ahead. By investing upfront in this technology, you establish a shield against future price hikes. While a grid-connected solar power system may still involve some grid-bought electricity, a significant chunk of your power supply will be harnessed from the solar system, amplifying your defence against escalating energy expenses.

Harness More Renewable Energy

Despite New Zealand's reliance on renewable energy sources for most of its grid power supply, a notable 10-20% still stems from fossil fuel generators, like the Huntly Power Station.

Solar power stands out as an exemplar of renewable energy, drawing from the sun's ceaseless and abundant energy reserves, which remain inexhaustible and non-depleting. Unlike finite fossil fuels, solar power operates without emitting pollutants or greenhouse gases. Its low environmental footprint, the potential for localised and decentralised generation, and its role in enhancing energy resilience establish it as a crucial catalyst for reducing carbon footprints and confronting the pressing issue of climate change.

Integrating a solar power system onto your rooftop increases your personal consumption of renewable energy and sends more renewable energy out to the grid.

No Need For Costly Battery Storage

Using The Grid As Back Up

During times when your solar panels aren't generating enough electricity (e.g., at night), you can still draw electricity from the grid as usual. This eliminates the need for energy storage systems like solar batteries in a basic grid-tied solar system, as the grid serves as a reliable backup source.

Enhancing Grid-Connected Systems with Battery Integration

Following the initial installation of a grid-connected solar power system, the seamless incorporation of battery storage becomes a viable option. Many New Zealanders are adopting a two-step approach, beginning with the installation of a solar power system and subsequently integrating batteries when financial resources permit, given that battery costs, remain substantial. These batteries, however, emerge as an exceptionally dependable electricity source during blackouts.

For those with an established solar power setup, the addition of an AC-coupled battery is recommended due to its simplified configuration in comparison to a DC-coupled battery. This approach allows the existing solar power system to remain untouched while introducing the battery configuration as an extension.

How To Make The Most Of A Grid-Connected Solar Power System

The best way to optimise a return on investment with a grid-connected system is by utilising as much generated solar power as possible.

Using self-generated solar power is worth-while; why waste money on expensive grid power? (typically around 30 cents per kWh). Immediately taking advantage of solar power is the best option for return on investment. Using solar power directly is known as solar power self-consumption, you can find more information on: solar power self-consumption.

Regular Energy Bills With A Grid Connected Solar Power System; What to Expect

Separate line items will be viewable on the power bill each month; On the first line is the amount of power used, the price per unit and the total cost of power used (imported power). The second line shows the amount of solar power exported to the grid, the price per unit the energy retailer is paying, and the total credit amount received from exporting power. This credited amount will be subtracted from the total cost of power used.

Find out what different energy retailers pay for: exported solar power here.

How Does A Solar Panel Work?

Standard solar panels have at least a dozen silicon squares within the frame (solar cells). Solar cells convert sunlight (photons) into an electrical current.

Silicon is a semiconductor; it's able to absorb a percentage of the photons emitted by the sun as they hit the solar cells. As the solar cells are bombarded with photons, the electrons are knocked loose, allowing them to flow freely.

The solar cells have an electric field that allow loose electrons to flow in one direction. Metal contacts (both on top and the bottom of solar cells) allow the current to be fed through a solar cable to reach the solar inverter. As DC electricity is created via solar cells, the inverter converts the current into AC electricity; you then have electricity to be used however you choose!

Check out our Components page for more information about solar panels and other solar system parts, components and essentials.

Video: How Solar Panels Work - A Basic Overview

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