– So, a five kilowatt solar power system gives you five kilowatts of power, right? Well, not really. (upbeat music) So in this video, we’re going to look at some of the misconceptions about how a solar power system is sized and what that means. So to do this, we’re going to look at four subjects. One is, what’s the difference between a kilowatt and a kilowatt hour?
And this is also the difference between power and energy. Secondly, how is the size of a solar system calculated? Thirdly, what does the solar system produce? And fourthly, how do you work out the benefit for you? So, what’s the difference between a kilowatt and a kilowatt hour?
Well a kilowatt is power. So when you turn on an appliance at home, like an air conditioner or a toaster, it will use a certain number of kilowatts at a certain point in time. Kilowatt hour is how many kilowatts is used over the course of one hour. (toaster popping) So that’s the difference between power and energy. Now, why is this important?
Well, it’s important because when you buy your electricity from your retailer, you’re actually buying kilowatt hours.
So it’s important you understand what a kilowatt hour is versus a kilowatt. So how is the size of a solar system calculated? Well, if you have a look at one of these panels, each of the panels has a wattage rating. So the one we’re showing you here is a 350 watt panel, so therefore 10 of them has a rating of 3.
5 kilowatts, and 20 of them has a rating of seven kilowatts. But that doesn’t mean they will output that amount of power at any given point in time, because that rating is done in the factory in a, what I’ll call a perfect environment, which is 25 degrees C with a fixed amount of light. It is rarely 25 degrees C, and it’s rarely going to have that fixed amount of light when it’s up on your roof. And then we have other things like some losses through the cables, and how far they are away from your meter box, et cetera, et cetera.
But the reason this number is important is because everyone in the industry is therefore able to use the same number at the same starting point.
So what does a solar system produce? Well, let’s just stick with a five kilowatt system for the moment because it’s a round number. So a five kilowatt system, as I said before, will rarely output five kilowatts. In some instances, it may be more than five kilowatts. But because you buy your electricity as energy, in other words, in kilowatt hours, we measure the output of the solar system in kilowatt hours, which is really important.
The power at any given point is not quite so important as how many kilowatt hours you get over the course of a day, a month, a year, or the system’s lifetime.
So a five kilowatt system, using guidance numbers from the Clean Energy Council, will produce around 20 kilowatt hours per day on average across the year. Now it’s gonna be more in summer, it’s going to be less in winter. More on a sunny day, less on a cloudy day and so forth. And on a partly cloudy day, of course the output goes up and down with the sunshine.
So, the five kilowatt system will give you about 20 kilowatt hours per day on average. So how do you calculate the benefit? Well if we take that 20 kilowatt hours per day on average across the year, you multiple that by 365. So a standard five kilowatt system should deliver around 7,200 kilowatt hours of energy over the course of the year. And it really is a simple matter of if you use all of that at the time it’s generated, which you are unlikely to do, then you would save 7,200 times the amount you’re paying for power.
So if that’s, call it, 20 cents per kilowatt hour, you’re going to save about $1,400. If it’s 30 cents, it’s around $2,100. If you don’t use any of it, if you close up your house and go away for a year and turn everything off, then you will export it all to the grid, and you’d multiply that 7,200 by what you get for your feed-in tariff. And if that was 10 cents, you’d get $720. Now the reality is no-one uses all their solar power, nor do they export all their solar power, so you will be somewhere in the middle.
And it’s simply a matter of working out, on average, where you’re likely to be. And that’s how you work out the benefit. It’s also how you work out the size of your solar system. The simplest way to work this out is to give one of our team a call on 1300 221 586.
And in about five or 10 minutes, they can help you through all the details of this and help you work out the right size solar system for you, and the benefits you’ll get.
Or alternatively, just click on the link below and download our solar guide, which also has all this information in it..