Grid Connect Solar Power Inverters
Most solar power systems in use in Australia are of the grid-connect type. When a grid-connect solar power system makes more electricity than is required, the extra power can be fed back into the power grid for other homes to use. When the solar panels are not making enough electricity, power can then be then drawn from the grid.
Grid-connect solar power systems must have a grid-connect or grid tie power inverter. This type of solar inverter can sync with the power grid producing the same power as the network uses, 240V AC sine wave electricity is generated from the DC output of the solar panels. The 240V power from a grid tie inverter is precisely the same as what is in use on the main power grid.
Below is a photo of a typical grid connect inverter, in this case, manufactured by SMA.
What does a grid connect power inverter do?
A grid tie inverter makes electricity that is an exact match of the voltage and frequency of that which is used in the grid, 240V AC sine wave. The electricity flowing through the power grid is not uniform the waveform and voltage of this power is quite imperfect and can vary significantly in a 24 hour period, for this reason, the grid tie inverter will monitor these changes and make corrections to match the power it outputs to the grid.
Why do grid tie inverters sometimes shut down?
If the grid's power frequency or voltage gets too high or, too low a grid feed inverter may shut down as there is a limit to the variation in electricity frequency or voltage that the inverter is capable of dealing with. A good quality inverter will restart itself after a shutdown event, and cheaper models may require a manual restart, in most cases just pressing a reset button will do the trick.
Installing a grid tie inverter
All grid connect inverters have an Ingress Protection (IP) rating, this rating indicates how well the unit is sealed against the weather and moisture and where it should be mounted:
- P21 – Indoor use only.
- IP42 – can be installed outside but must be covered and enclosed.
- IP65 – can be installed outside, uncovered.
The best place to mount an inverter is in a cool place as heat is the enemy of power inverters, and of course, the location needs to be secure and out of the reach of children and preferably the elements.