Grid-Connect FAQs

How does it work ?

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A grid-connected solar power system comprises of two main mechanisms being the solar panels and an inverter. The solar panels are usually mounted on the north facing roof of the house and generate electricity from the sun in the form of DC electricity. On a residential house typically between six to thirty or more solar panels are connected together in the one solar power system. The function of the inverter is to convert the DC electricity into AC electricity at the appropriate voltage so that it becomes compatible with mains grid power and is suitable for use in the home.

 

The electricity that is generated from your solar power system may be used in your home or by someone else who is connected to the electricity grid. The power that you generate is used primarily in your own home, however if you are generating more power than you are using, then the excess is “exported” to the grid and that quantity is metered (as is the power that you consume from the grid). If you are using more power than your solar system is generating at any given time, then extra power from the grid will supplement your solar power to provide your needs. All of this happens in a seamless manner such that there is no interruption to your supply.

Most households with grid-connected solar power will generate an excess of power, during the middle of the day when the sun is shining, most of which is exported to the mains grid. Then when the sun goes down, power will be supplied from the grid back to the house. The grid may be thought of as a kind of battery or storage system for your solar electricity (although this is not actually the case).

With an increasing number of houses connected to the grid that are generating solar power, the demand on coal fired power stations to supply the grid during daylight hours is being reduced.

Why should I have a grid-connected solar power system installed ?

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The reasons for deciding to install a grid-connected solar power system are usually:

  • To reduce electricity bills

The solar power that is generated from your system will be either used to power any appliances you have on at the time or exported to0 the grid for other people to use. The component that is used in your house will directly offset your peak-rate power consumption. The balance (if any) will be exported to the grid and metered as your net feed-in amount. Your electricity company pays or credits you for this power at an agreed rate (currently minimum of 8c per kWh in Victoria). A solar power system will offset your electricity bill by anything from a small portion to the entire power bill, depending on the size of the system and the electricity demands and usage habits of the household.

  • To reduce carbon emissions

Solar power is a clean and renewable source which offsets the carbon that would otherwise have been created by a coal fired power station. With modern manufacturing techniques that are now used in the construction of solar panels, a solar power system will offset the embodied energy in its components (required to manufacture the panels, inverter, etc.) in less than 2 years, after which time it is generating truly clean energy for the remaining 20+ years of its lifetime. The power generated from a 1.5Kw solar power system, installed in Melbourne, will offset about 2.4 tons of CO2 per year. This reduction of greenhouse gasses makes a very important contribution to helping the environment. This alone is a good enough reason for every home in Australia to have solar panels on the roof.

 

Is there still a government rebate available for new solar power installations ?

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There is still a form of rebate available, that is from the sale of Renewable Energy Certificates (RECs, also referred to as STCs) which are generated when a system is installed. These certificates can be sold for cash or more commonly exchanged for an up-front cash discount on the purchase price of the new solar system. The value of this discount as at June 2013 is about $1900 for a 3kW system and around $6200 for a 10kW system.

What is a feed in tariff ?

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The price that the electricity company pays for the power that is exported from your solar power system to the grid is called a feed-in-tariff. All states and territories in Australia now have a net feed-in-tariff system. That is, the power generated from the system minus the power used in the house (at any instance in time) is counted as export.

How much is the feed in tariff in Victoria?

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As of October 2012, electricity retailers are only obliged to pay a minimum of 8c/kWh for new solar installations. Some retailers will pay a few cents more than this though, so it is worth shopping around for the best deal.

Given that the rate that retailers charge for power during the day (peak rate) is now around 30c/kWh, many believe that the current feed-in-tariff system is unfair and does not suitably reward people for their clean energy production.

What size solar power system do I need ?

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The size of the system usually depends on several factors including available roof space, intended purpose and budget. The extent to which the solar power system will offset your power bill can be estimated using information from previous power bills and by looking at what electric appliance are in the house and their typical usage patterns.

With the recent change in feed-in tariff, the maximum benefit from your solar power will be achieved by using as much as possible of the solar power in the house directly as it is generated, rather than aiming to maximise the feed-in component. This can be done by means of running appliances such as washing machines & dishwashers during the middle of the day rather than at night for example.

Please contact us if you would like an estimation of the system size you require to offset your power bill.

Where do the solar panels need to be mounted ?

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Ideally the solar panels will be mounted on a north facing roof with a pitch of between 10 and 30 degrees. If there is little or no north facing roof on the house, the solar panels may still be mounted on an east or west facing roof, but the efficiency of the system will be reduced by around 12-13%. Therefore to achieve the same output from the system (as if it were facing north) the system must be upsized by around 12-13%. If the roof is flat the solar panels must be mounted on a frame that is tilted to the north.

 

The area where the solar panels are to be mounted must be free of shading between the hours of 9am and 3pm all year round. Preferably they will have no shading what-so-ever. Even a small patch of shade on one of the solar panels will affect the whole system considerably. For example if 5% of the total area of solar panels are shaded, then the output of the system might be reduced by as much as 20%.

Will I have power from the solar panels in the case of a mains power black out ? 

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No. A grid-connected solar power system must automatically shut down if there is a fault with the grid supply for safety reasons.

Do I need to have a new meter installed ? 

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You will most likely need to have a new bi-directional meter installed once you have had your solar system installed. This may be different to some electronic  meters even if they have been installed within the last 2-3 years. If you have already had a suitable “Smart Meter” installed then it will just require re-programming. Upon completion of the solar installation and electrical safety inspection, the installer will submit the relevant paperwork to your electricity retailer to have the new meter installed/configured. Depending on the area which you live in there may be a delay of up to 1 month before the meter is changed, some areas are much quicker.

 

What is the cost of the new meter ? 

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The meter itself is provided free of charge however there is a fee for the installation which varies from retailer to retailer. It is usually in the vicinity of $200 – $500. This fee will usually appear on the next electricity bill after the meter is installed. Some retailers also charge a minimal ongoing fee for the new meter (as with smart meters).