Energy Storage

To help understand Energy Storage a littel better we have provide a simple explanation with images for the three main solar power systems currently on the market today.

To view the images in better detail, please just click on the image.

The three main types of solar power systems are:

1. Grid-Connect – also known as grid-tie or grid-feed solar system
2. Off-Grid – known as a stand-alone power system
3. Battery Hybrid – Solar Grid Connected with battery storage

Grid Connect
system example

Grid-Connect

Grid-Connected solar systems are by far the most common. These are grid-tie systems which are connected to the public electricity grid and have no battery storage. Solar power that you generate from an

on-grid system is first consumed by the loads in your house and any energy that is not used is exported back to the electricity grid. You will usually get paid a feed-in-tariff (FiT) for the energy that you export to the grid and the price you receive for this depends on the price you are able to negotiate with your energy provider. Some states still have feed-in-tariffs in place.

Grid-tie systems are not able to function or provide electricity to the home at night, blackout or power outage. This is for safety reasons (AS4777) as a blackout usually occurs when the electricity grid fails, if the solar inverter was still generating electricity, it can risk the safety of the people working on the the electricity network. This is also the standard for the battery hybrid system. Most battery hybrid system but not all will then then switch to the battery management system which will manage the power to you home while the power is down with the energy stored in the batteries. As soon as the power is reconnected your inverter will detect this and then resume normal functions.

Battery Hybrid system example

Battery Hybrid

People with existing solar grid-connected system who are looking a switching to a hybrid battery system will more than likely need to have their current grid connected inverter replaced with a hybrid inverter.

The new hybrid inverters have the grid-connected inverter and the battery management inverter all in the one box.

Some people who are upgrading the size of the solar array on their roofs and who also need to upgrade the size of their inverter at the same time are replacing their current grid-connected inverters with a Hybrid inverter. Some are connecting batteries straight away and some are happy to wait for the cost of batteries to come down. The system is called a Battery Ready where the customer does not install the batteries with the hybrid inverter and it will not be able to provide any power at night or when the grid fails.

When batteries are installed with the hybrid inverter the solar energy that is generated during the day will then be stored into the batteries. Normally the solar is first assigned to go into the batteries (just like we would do in an off-grid system).

This is so the batteries heath is maintained, the life of the batteries is looked after and the warranty guidelines specified by the battery companies is adhered to.

As soon as the batteries are fully charged the energy is then available to be used by the loads in the home. Any excess energy that is not consumed in the home during the day is then sent back to the grid.

At night when the stored energy is depleted, the grid is there as a back up, making sure that the power is always available. The system can also be set up so you are able to charge the batteries using cheaper off-peak electricity rates (usually after midnight to 6am). The options available for these styles of Hybrid systems is constantly growing and it is a very exciting time for solar energy.

One note to remember is that not all battery systems will cover the complete load in you home. Most have been designed to only cover a certain amount of circuit loads and hours. This of course depends on the size of the system, just like in off-grid.

Off-Grid system example

Off-Grid

An off-grid system is not connected to the electricity grid and the house/property relies solely on battery storage. In an off-grid system an accredited solar designer needs to design a system that has enough power generation and battery storage to meet the home’s requirements. Many Off-Grid systems that have not been designed correctly will need to have the batteries replaced much earlier (around 4 years) compared to 8 and even 12 years depending on the quality of the battery’s installed and the discharge % set.

With all the components and high cost of batteries, off-grid systems are comparatively more expensive than grid-connect or Hybrid grid systems and so are usually only found in remote areas that are far from any electricity grid or installed by really passionate environmentalist.

Now that battery costs and battery technology are becoming main stream, hopefully we will see lower cost and improved technology changes in the near future. It is really important to everyone not just for the solar industry, that safe battery storage and technologies is first on the list for all.