Grid Tie Inverters are the next biggest cost after solar panels. Grid tie inverters take the low voltage electricity that is produced by the panels and convert it into mains voltage electricity (120 volts or 240 volts) that can be used in your home to power appliances and other mains gadgets. This electricity is fully in phase and compatible with your mains and the inverter connects into your home electricity system.
A decent grid tied inverter will cost, on average, around $0.70 per watt, and prices can start at less than $100 for this type of inverter and go upwards.
When installing a solar panel system it is always worth installing more than one grid tie inverter for the simple reason that if one inverter should fail ( and they can) you will have some redundancy and will still be able to generate power from the remaining inverter.
So rather than say installing a single 2kw inverter for your installation you should consider using two 1kw inverters instead which will also help with cooling and general performance and efficiency.
Grid Tie Inverter Features
Efficiency is the most important factor when considering which grid tie inverter to use but, in many cases this can be difficult to determine accurately. Manufacturers tend to talk about their peak efficiency but this only occurs when the inverter is fully loaded and getting maximum input from the solar panels.
When selecting an inverter, look for one that has a high efficiency over a wide range of conditions, including input power, temperature, output load and varying grid power.
How Does a Grid Tie Inverter Work?
A grid–tie inverter takes the electrical current from the solar panels, typically 12 volts DC and converts this into grid mains voltage, 120 volts or 240 volts AC. The inverter automatically monitors the frequency of the mains voltage and converts the DC current in a manner that puts it into ‘phase’ with your household mains. In other words the power that you make is fully compatible with your household current.
Simply put a grid tie inverter allows you to connect your solar panels directly to your household mains, which will reduce the amount of electricity that you need to buy from the utility company.
Grid Tie Inverter Safety Features
All grid tie inverters have built in safety features. Some of these will vary from model to model. The key feature is that they will automatically cut themselves off if the mains utility voltage drops off ( for example if there is a power cut or outage).
The reason for this is very simple – if your inverter continued to generate power then this power could potentially be sent out into the grid and into equipment and power lines that might be being repaired by utility workers. This could present a real danger of shock, hence this one reason why grid tie inverters switch off when mains power goes off.
What Is The Difference Between Grid Tie and a ‘standard off grid’ Inverter?
A grid tie inverter allows you to ‘tie in’ your solar panels, or other renewable generation system, into the household mains. A ‘standard’ inverter converts 12 volts DC into 120V or 240V AC that can be used ‘standalone’.
So, for example, if you go camping you may have a vehicle with you. You can connect a ‘standard’ inverter to the 12V battery in your car and the inverter will convert this into 120/240V which you can use to power your mains voltage items that you might have with you.
If you were going completely ‘off grid’ with no power from the utility company, and if you still needed mains voltage for your devices and appliances, then this is the type of inverter that you would use.
Standard or ‘off grid’ inverters are often reliant on being connected to battery banks which are fed power from the solar panels, the battery charge levels are controlled by separate charge controllers that prevent the panels from overcharging them and stop the inverter from over discharging them.
These ‘standard’ inverters tend to have plug sockets on the back of them, as can be seen on the example on the left, they are portable and come in a range of sizes, and, because they are not used to connect to the grid, they also tend to be cheaper.
You can find out more about off grid inverters in our article here.
Can you do a DIY Grid Tie Inverter?
If you are installing your own solar panel system then it is perfectly possible to add a grid tie inverter to the system yourself. There are many grid tie inverters available and many of these offer almost plug and play level installation.
Still Not Clear How They Work?
Check out this great informative video from GreenPowerScience.