Make hay and electricity while the sun shines.
Solar cells generate DC (direct current) electricity from sunlight. The solar cells are combined in a panel / photovoltaic module. Several panels combined build the array. The panels are hail tested and sealed against corrosion.
Photovoltaic power capacity is measured as maximum power output under “standardised test conditions” (STC, you will find this on the data sheets of the solar panel manufacturers) in “Wp” (Watts peak). STC makes it possible to compare one panel product with an other, but does not really reflect the real life conditions: STC are under module temperature of 25° Celsius and radiation of 1000w/m2. In reality (it gets over 70° Celsius on your roof and radiation with an average 5350 Wh/m²/day. The radiation in winter is around 2500 w/m2, in Summer up to over 8000) your panel produces way more, because there is more sun radiation, but a little less, because it is mostly hotter than 25° C.
So on one hand you compare panels under standard conditions that rarely happen (but at least you can compare the panels performance) and on the other hand there are many variables on an install in real live conditions: roof orientation, roof angle, cable length of the system, temperature on the roof (yes: the colour of the roof makes a difference), cleanness of the panels (dust, bird droppings, leaves), hours of no partial shading, general weather conditions, the conversion rate and temperature behaviour of the inverter. That’s why we give only estimates of the expected performance, but the calculations encounter all these variables.
The DC electrical energy goes to the inverter, where DC (direct current) is changed into 240V AC (alternating current). The inverter does this in an as efficient way as possible (you can compare the efficiency of inverters comparing the EU (or European) efficiency. Inverters need to have a big temperature range of operation. Specially in Australian conditions it’s important to have the matching inverter and the right position, where the inverter is mounted. Another relevant factor an inverter has to cover, is the range of AC voltage it can run with. This comes into play, when the grid is running on a slightly higher voltage, something a home owner or his electrician has no influence on. And last but not least: with the inverter you buy a dependency on a company that ideally has a representative within Australia and is able to stay on the market for many years to come.
Once the electrical power is changed from DC to AC current, it runs through your utility meter and your switch board to power the appliances of your home. The surplus of electricity you don’t consume in house will go into the grid - your meter will record the in- and outgoing electricity. At night, when your panels are not producing power, you receive all the power off the grid. In case of a grid failure or an interruption, for example because of services on the grid, your inverter shuts your solar system down. This means you are, with a grid connected solar system NOT independent from the grid.
For any questions you might have we try our best to answer them when we meet.
Estimate of average daily power production
on a North facing roof 30° pitch in Perth WA
|2 KW||8.8 kWh|
|3 KW||13.2 kWh|
|4 KW||17.6 kWh|
|5 KW||22 kWh|