Solar power options: Going on-grid or off-grid
What's the difference between on-grid and off-grid solar power systems?
Most solar power systems in Australia are on-grid, which means they're connected back to the main energy network. When your solar panels don't cut it by themselves, you can make up for the shortfall by buying from the grid.
If you can't connect to the grid, or if you're interested in self-sufficiency, you may be able to go off-grid. In this case, you won't have access to the safety net the grid provides and if your own power runs out, that's it.
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How does an on-grid solar power system work?
An on-grid solar power system is hooked up to the main power network and linked to your energy supplier. These systems are referred to by various names, including grid-tied, grid-connect and grid-direct systems, but they're the same thing.
Because you're connected to the main power supply for your area, your solar panels don't have to produce all the energy you need. And if your system produces more energy than you can use at any given time, you can feed the excess back into the grid and get paid according to your energy plan's solar feed-in tariff.
What do I need for an on-grid solar power system?
The requirements for this type of solar power system are simply what you need to generate power from the sun, and a professional to install it. The essential main components are:
- Solar PV (photovoltaic) panels, to generate electricity from sunlight.
- An inverter or micro-inverters, to convert the power into a more useable form.
- Electrical safety gear like breakers, fuses and disconnects
- A meter, to monitor energy production so you can take advantage of feed-in tariffs and track your system's performance.
Even with an on-grid solar power system, you may still experience power outages when there's a failure on the grid. This is because all on-grid systems are powered down during repair periods to reduce the risk of electrocution.
How does an off-grid solar power system work?
The use of off-grid solar systems is more common in regional and rural parts of Australia, where people cannot connect to the grid at all. It uses the exact same components as an on-grid system, with a couple of important differences.
The first is that your system is likely to be larger than an on-grid system to power your home all year round. The second is that you'll have to incorporate a solar battery system so that you can store power for night time use and during the winter, when days are shorter.
With an off-grid system, you also have to regularly check your energy usage and storage to make sure you keep your output below maximum levels. Otherwise, you could overload the system or run out of power altogether.
What do I need for an off-grid solar power system?
Off-grid solar systems need the same components as on-grid ones, plus:
- Battery bank, to store excess energy.
- A charge controller, to prevent the battery from overcharging.
- A DC disconnect, to switch off current between the battery bank and inverter for maintenance and safety.
- A backup generator (if you want), in case of cloudy days or other problems.
- Professional installers
Hybrid solar power systems
A hybrid system is simply an on-grid system that incorporates the use of a battery backup. Power from your solar system and potentially the grid work to charge the battery backup. You can either switch the battery on in case of a power outage, or you can store the energy to push back into the grid at a time when you might receive a higher feed-in rate.
The components that go into making a hybrid system are essentially the same as in any on-grid system, with the addition of a suitable battery backup.
On-grid vs off-grid
Choosing between an on-grid and an off-grid system boils down to whether or not you have access to the grid. If the infrastructure isn't there, going off-grid will almost certainly be cheaper than trying to get a grid connection.
If you do have access to electricity from the grid, installing an on-grid system makes more financial sense for a few reasons:
- Reduced equipment and maintenance cost on solar batteries and other components.
- Easy source of backup power from the main network.
- You can take advantage of solar feed-in tariffs by feeding excess power back into the grid.
The only other reason to consider off-grid is if self-sufficiency really appeals to you and you want to be 100% sure all the power you're using is guaranteed renewable.
It isn't really a case of which is better and which is worse. They both have pros and cons.
On-grid solar may allow you to make a little money by selling energy back to the grid and should, in theory, cover you for any shortfalls, whereas off-grid solar will not offer this.
In the same way, many people believe that energy independence is important, and this can only truly be achieved with an off-grid system
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