A little while Gold Coast Solar Power Solutions was asked to provide a solar power proposal for a local Gold Coast childcare center which of course we were very happy to do. After submitting our proposal we did not hear from them for a couple of months so we gave them a call. The manager proceeded to tell me that they had signed up with another company for a much larger system than we had proposed. Let’s just look at this situation and the savings this childcare center can expect.

Firstly some background on the current state of solar power feed-in tariffs in QLD. You may or may not be aware that the current QLD solar power net feed-in tariff pays 8c per kWh for any surplus solar; this is the power that the solar power system has produced but has not been used on the property at that moment so it has been sent back to the power grid as surplus electricity to be used next door or where ever it is required. The electricity account holder currently gets paid the feed-in tariff rate of 8c per kWh of surplus power, plus any further incentive that their electricity retailer offers such as those offered by Click Energy.

What you are probably not aware of is some of the finer details of this feed-in tariff which can be found on the website here, mainly as follows:

  • The 8c solar power net feed-in tariff will end on the 30th of June 2014, so customers who are receiving it now will lose it altogether.
  • For a solar power system to be eligible for the 8c solar power net feed-in tariff the inverter capacity cannot exceed 5 kilowatts.With this information in mind I recommended to the owner of the business that we install a power monitoring system for a week to establish how much power was being used at the site and so we could analyze the data and determine the best possible size of solar power system to give the best return for the business, he agreed to this and after a week I had the following data.chilcare business days
    The graph above shows the childcare centres power consumption from midnight to midnight on a weekday, a perfect example of a power load suited for a solar power system to cover, averaging around 6 kW during the day.
    childcare weekend
    The graph above shows the childcare centres power consumption from midnight to midnight on a weekend. As the facility is only used on weekdays this is just stand by loads and fridges etc. The average load here is around 1 kW, both day and night.

    Our Solar Power Proposal

    From this data, it is clear to see that a solar power system producing much more than 6 kW of power would be producing a fair amount of surplus solar power to the business’s requirements, and this additional solar power production would be going back to the grid as surplus power at little to no benefit to the business, remembering from the information above that a system with an inverter larger than 5 kW will not be receiving the 8c state feed-in tariff, therefore the maximum they could receive for this surplus power would be 8c per kWh from the electricity retailer AGL; Click Energy pay 10c per kWh but they have their feed-in tariff capped at a 5 kW system as well.

    Taking all this information into account we provided a solar power proposal specifying 30 x quality REC 250W solar panels (7.5kW in total) coupled with an SMA Sunnyboy 5000TL inverter for the following reasons (a side note half the panels were to face NE and half NW):

  • We want as close to 6kW of power being produced as possible.
  • We want to be eligible for the solar power feed-in tariff if possible to ensure maximum return on the investment; keeping the inverter size to 5 kW retains this eligibility so the site can benefit by receiving a higher tariff on weekends.
  • This system will produce 5kW of solar power from 9 am to 3pm most days, nicely matching the sites weekday requirements.
  • Below are the same graphs with an estimated line of solar power input to offset the power consumption.
    graph-with-solarUsing these premium, high performance products our calculations, taking into account the business using all the power produced on weekdays and only 1 kW per hour being consumed on the weekends with surplus going back to the grid on the net feed in tariff came up with the following:
  • Quarterly Savings on Power Bills: $635
  • Yearly Savings on Power Bills: $2,540
  • Expected Pay Back Period: 4 years
  • Expected Savings Over 10 years: $27,000As can be seen this is a very nice return from the investment in solar power and with quality components as specified the customer could expect continued high performance and trouble free operation for much longer than 10 years with free electricity every single day! As I mentioned at the beginning, unfortunately our proposal and the reasoning behind it was not taken into consideration.

    Solar Power System Installed at the Business

    On following up this business about our solar power quotation I was told by the manager that they had gone with another company with a 15 kW system and that they would be selling all the surplus power on the feed in tariff. My alarm bells where ringing!! Let’s look at the immediate issues:

  • The system is way bigger than they actually require
  • They have been lied to, they will not be eligible for the feed in tariff as the system has an inverter larger than 5 kW in size
  • Even if they were eligible for the net feed in tariff it is not in the businesses best interests as they are not paid well for it.Lets have
  • Quarterly Savings on Power Bills: $1050
  • Yearly Savings on Power Bills: $4,200
  • Expected Pay Back Period: 4 years
  • Expected Savings Over 10 years: $27,000