1. Hybrid Solar Power Plant (Grid Export with battery backup)
Hybrid System : Due to the decreasing cost of battery storage. systems that are already connected to the electricity grid can start taking advantage of battery storage as well. This means being able to store solar energy that is generated during the day and using it at night. When the stored energy is depleted. the grid is there as a hack up, allowing consumers to have the hest of both worlds. Hybrid systems are also able to charge the batteries using cheap off-peak electricity (usually after midnight to Barn).
The battery bank. In hybrid system once solar power is used by the appliances in your property, any excess power will be sent to your battery bank. Once the battery bank is full. it will stop receiving power from the solar system.
The meter and electricity grid. Depending on how your hybrid system is set up and whether your utility allows it, once your batteries are fully charged excess solar power not required by your appliances can be exported to the grid via your meter. When your solar system is not in use. and if you have drained the usable power in your batteries your appliances will then start drawing power from the grid.
2. On-Grid Solar Power Plant (Grid Export with battery backup)
On-Gride System : On-grid or grid-tie solar systems are by far the most common and widely used by homes and businesses. These systems are connected to the public electricity grid and do not require battery storage. Any solar power that you generate from on-grid system (which is not used directly in your home) is exported onto the electricity grid and you usually get paid a feed-in-tariff (FIT) for the energy that you export.
In an on-grid system, this is what happens after electricity reaches the switchboard:
The meter Excess solar energy runs through the meter, which calculates how much power you are either exporting.
Metering systems work differently in many states and countries around the world. In this description I am assuming the meter is only measuring the electricity being exported to the grid, as is the case in most of Australia. In some state meters measure all solar electricity produced by your system, and therefore your electricity will run through your meter before reaching the switchboard and not after it. In some areas (currently in California), the meter measures both production and export and the consumer is charged (or credited) for net electricity used over a month or year period. I will explain more about metering in a later blog.
The electricity grid. Electricity that is sent to the grid from your solar system can then be used by other consumers the grid (your neighbours). When your solar system is not operating or you are using more electricity than your system is producing, you will start imparting or consuming electricity from the grid.
3. Off-Grid Solar Power Plant
An off-grid system is not connected to the electricity grid and therefore requires battery storage. An off-grid solar system must be designed appropriately so that it will generate enough power throughout the year and have enough battery capacity to meet the home's requirements, even in the depths of winter when there is less sunlight. The high cost of batteries and inverters means off-grid systems are much more expensive than an-grid systems and so are usually only needed in more remote areas that are far from any electricity grid.
The battery bank. In an off-grid system there is no public electricity grid. Once solar power is used by the appliances in your property. any excess power will be sent to your battery hank. Once the battery bank is full it will stop receiving power from the solar system. When your solar system is not working (night time or cloudy days), your appliances will draw power from the batteries.
Backup Generator. For times of the year when the batteries are low on charge and the weather is very cloudy you will generally need a backup power source, such as a backup generator or gen-set. The size of the gen-set (measured in kVA) should to he adequate to supply your house and charge the batteries at the same time.