Solar power systems

Is it worth putting solar panels on your roof?

Solar power systems provide free, renewable energy from the sun. A solar powered grid connected system generates clean electricity via panels located on your roof. This can be consumed in the household or fed back into the electricity grid.

When the sun shines on solar panels connected to solar power systems mounted on your roof, it generates DC electricity. This DC electricity is fed into a solar inverter which converts it into 240V AC electricity. The same AC electricity as your mains supply, can be used in your home to power your appliances. Any surplus electricity generated by the solar power system not used by your appliances is fed back into the mains electricity supply grid.

There are some factors that you need to consider when trying to calculate a systems payback time and likely energy output. These include: the effectiveness of solar panels depends on the direction the panels are facing, north facing is ideal. They should be pointed directly at the sun, at the right angle and without shading from trees or other stuctures. Where you live is another factor as some states are sunnier than others .

Diagram from


Personal experience

I ‘ve had a 1.85kW solar power system for two years now and have not had to pay the electricity bill yet, (only the inital cost for reconfiguration of the meter) and are $400+ in credit.

It consists of 10 x 185W Conergy panels and a 2kW Eaton inverter.

Our panels are installed on a west facing roof and the inverter is undercover next to the backdoor. Which is handy to see how much power is generating at any given moment. Yet very distracting especially in the first few months. I was always checking to see how much energy was produced. It was very addictive. Watching the numbers go up and getting all excited and then disappointed when the numbers went down. Kinda like the stock market!

The reason we decided to get a solar power system was to hopefully eliminate our electricity bill. An added bonus was the Premium feed in tariff (credit for excess electricity fed back into the grid) that was on offer. Plus we are doing our bit for the environment as small as it may be, it’s something!

Prior to the installation of the solar power system, our electricity was charged at a single rate. Since the solar power  system has been turned on we have been moved to Time of Use (TOU) rate. Which means there is peak and off peak rate.

In the first month or so, l noticed the peak output was around 1.2kW on sunny days which seemed quite low but l did read that they need to “burn in”. Which seemed to be true because not long after that, the average peak on a sunny 20⁰C odd day is usually 1.5kW.

You can not get peak output the same amount as the size of your system (eg. 1.85kW system not = 1.85kW peak output) because they are not that efficient. Also, the hotter the weather the less efficient the panels are. On 30⁰C odd days it peaks at 1.2kW.

On a 17⁰C, cloudy, rainy cold autumn day in April with occasional sunny breaks it generated a total of 4.73kWh.  Which isn’t a lot but better than nothing. The highest total output I’ve seen was 12.54kWh on a 23⁰C sunny January day. That definitely covers our average usage! Hopefully, the credits from the sunnier months will cover the colder months.

The durability of the panels was put to the test when we had hail the size of golf balls on Christmas day (of all days). The panels were inspected right after the hailstorm and there were no visible signs of damage to the panels and it continued to work as normal.







Things I learnt:

Prior to purchase, I knew nothing about solar power systems except that they generate energy from the sun.  I had to educate myself and did a lot of reading til my eyeballs nearly popped out of my head!

Here are some things that I learnt:

1. Most panels have a 25 year warranty that they will work 80% of their efficiency.

2. Most inverters have a 5 – 10 year warranty.

3.  Not all stores will be around that long.

Many stores that were on my short list including the store that I bought my solar power system from have since closed within the first year of my system installed.  I made sure that the manufacturers of the panels and inverter that I purchased had a presence within the country for this very reason.  Rather than trying to contact the manufacturers overseas.

4. Make sure you do your research on the panels and inverter you chose, not just the material that manufacturers put out about their products but also online forums to see other people’s experience.  This is also very true and important about the store/business you decide to purchase from.  I read horror stories of people waiting months on end waiting for their system to be installed or having trouble contacting the business.  Make sure you only put a deposit for the system once you decide to purchase and only pay the remaining once the system is installed and you are happy because there were some businesses that I came across that wanted upfront payment.

5. Some businesses will do a free pre-inspection of your roof for possible location of the panels and inverter, assess the impact of shading from trees or other structures, and answer any questions you may have.

6. Solar power systems are covered by home building insurance (make sure you contact your home building insurer to make sure it is covered).

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