Solar Power: Going Off-Grid or Staying Connected?

6th May 18

Cameron Quin

Written by Cameron Quin

When we think about energy independence, it is easy to imagine a building that is completely disconnected from the power network. We must also admit that the idea of unplugging from the grid is emotionally appealing, especially with the high electricity tariffs of Australia – some consumers saw their power bills double in less than a decade.

However, the power network connection also brings advantages, and going fully off-grid negates many potential benefits. A more effective approach is reducing your electricity expenses as much as possible with a commercial solar array or any other generation system, but keeping the grid connection. This article will describe some advantages of staying on the grid, even you plan to generate 100% of the electricity you consume.

You Can Use the Power Grid as Backup

Even if you can generate all the electricity needed by your building, remember that all equipment requires maintenance. Also consider that equipment can be damaged, requiring reparations and replacements. Although commercial solar arrays have simple maintenance needs, the system also includes inverters and other sensitive electronic components.

If you depend on self-generation and must shut down important equipment for service, you can simply draw electricity from the grid. On the other hand, your power supply is interrupted completely if you have decided to go off-grid.

You Can Sell Surplus Electricity with a Grid Connection

Assume you have an ample rooftop that gets a lot of sunshine, causing you to generate more energy than needed during the sunnier months. You are forced to use this energy in an off-grid installation, but can sell it for a feed-in tariff if you have a grid-tied system. Australian feed-in tariffs are significantly lower than the retail price of electricity, but they make surplus generation valuable by adding a price tag to it.

The Power Grid Provides Stability

Electrical appliances cannot operate with raw and unconditioned electricity. To be usable, it must have the right voltage and the right frequency, or equipment damage is almost certain. Voltage and frequency tend to fluctuate depending on power supply and consumption. They decrease when load is suddenly raised, and they increase when surplus power is being fed into a network.

The loads in homes and commercial settings are small compared with the total generation capacity connected to the grid. Therefore, the grid is very reliable as a reference point for voltage and frequency. On the other hand, an off-grid generation system is not much larger than the loads it serves, and power-hungry equipment can destabilise the voltage supply when activated.

Emerging Trends: Free Energy Trade and Virtual Power Plants

Although free energy trade would require extensive legislation, the concept is viable. Owners of solar power systems with surplus generation would not be limited to the feed-in tariffs of energy retailers, allowing direct negotiation with other energy consumers. There would still be grid operating costs, but these are simply added to the electricity price negotiated between parties.

Virtual power plants pool together the generation capacity of multiple systems, managing them like a single unit. The concept is also viable with energy storage systems such as lithium-ion batteries. Solar PV system owners may soon start receiving offers to participate in virtual power plant programs, in exchange for financial benefits. However, this concept requires a grid connection as well.


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