loader image

Learn to interpret your electric bill and control your expectations about the outcomes.

The process of assessing your site's suitability to solar power requires an assessment of your electric bill. You can find out more about this on this page , or send us your electricity bill and we'll examine it for you.

If your electricity bills are very expensive or you consume lots of electricity, you are charged differently than other customers. Even though you pay a cheap price for each one watt of power, you are charged a high demand charge. Small and medium-sized businesses can skip the demand charges, but they'll be charged general supply tariffs which have an increased cost per kWh of the electricity used.

On this page:

  • General Supply Tariffs for Small & Medium Enterprises – Case Study
  • Demand Tariffs for Large Enterprises
  • Case Study for a Large Enterprise
  • Summary


The power bill below was obtained from the account of a TGR Energy customer located in Queensland who is on the Ergon Energy network.

The "Tariff 20 General Supply is a straightforward price to adhere to since there is a fixed price for power during the day and the night. This company is a perfect option for solar because it is operational from 8 am until 5 pm, 7 every day of the week. This is when Solar generates the most energy. If the system is properly sized, the majority of the solar energy produced can be utilized at the site thus reducing the price that is $0.23 per kWh when purchased off the grid.

In this case our client, Bundaberg Wholesale Palms, was operating a pump that was irrigation of crops with water.

They used an 7.5kW pump but chose 11.5kW in solar panel which meant enough power would be generated to pay for all their expenses.

If they had chosen the 7.5kW system that was sized to be comparable to the dimensions of the pump they'd only be able to compensating their consumption at the time of day, when solar power is at its peak.

The customer also plans the addition of another pump the bill in the near future.

Bundaberg Wholesale Palms has a second account for electricity.

This second account is based an identical "Tariff 20 General Supply" combined with an residential tariff that provides electricity to the groundskeeper's property.

We have installed 36.5kW of solar panel across two different buildings that face North East and North West to make the most of the afternoon and morning sun.

To maximize the impact of the solar, we re-wired meters that were in place and moved load to the main 'Tariff 20 General Supply' as it was the tariff that which the solar is linked to.

Take a look at an image of entire site below, including the solar array used for pumps on top and to the right of the image.


hey are often the most difficult to understand.

If you compare the cost per kWh to the "Tariff 20 General Supply' it is at first difficult to figure out the reason why power costs are so expensive. When you conduct a deeper analysis, the real price becomes apparent.

This is how a huge power bill appears like on the right.

In the beginning, peak costs only amount to 6.9c per kWh. However, when you add in the 'Network Charges' and the 'Other Charges', the real cost per kWh is close to $0.10 per kWh, which is an increase of a significant amount but still a fair price for electricity.

There are numerous fixed costs associated with tariffs like this, for example TOUS Fixed Charges and DUOS that must be paid and cannot be diminished through solar.

The primary variable cost on the bill that solar may affect is the 'DUOS and Demand Above Threshold TUOS under Network Charges. In this particular example, these expenses make up 35 percent of the electricity bill.

This is moment during your billing period (usually monthly) in which the largest amount of energy has been taken off the grid the same moment. In many businesses this happens between 7am - 8am when computers and lights are switched on and air conditioners are turned on.

Knowing when the demand charges are due to occur is essential when assessing the potential of making a solar energy investment. It is possible to obtain this information from your energy supplier by requesting a twelve-month load profile, which is also known by the name of interval data. It can cost you up to $150, however it is definitely worth the money.

Here's a full day's worth of data culled from the interval data from the TGR Energy Account in Queensland.

The black spike in the graph is that of the Peak Demand Cost. If this was the biggest spike of the month customers would get charged for the equivalent of 108kW.

The bill shown above is an itemized one. It indicates a demand fee in the amount of $33.63 per kW. This means that this customer will be charged 108kW times $33.63 which amounts to $3,632.04 each month.

The great thing about the company's energy consumption is that the highest consumption occurs during daylight hours , particularly in the afternoon.

If we turn the panels West towards the sun, when they experience their power surges, then we can take a bite out of the demand charge and put an enormous dent in the cost.

If power surges happen at 9 AM, we'd place the panels facing towards the east. The savings derived from offset the demand charge is far greater than the savings gained through the offset of purchasing grid electricity with a cost of 10 cents for each kWh.

Even the possibility of being able to reduce the peak time to 3:00 pm, our customer will still be at 85kW peaking around 8 at night. The solar panel is not producing power, which means we're not able to make any changes. This is an excellent example of why it's important to collect the load profile details so we can control expectations for savings and estimate and quote in line with the load profile.

Our client chose 100kWP solar panels with 400 solar panels in order to cut down on the amount of power they consume during daytime hours of operation of the company. With a thorough investigation we were able find the machine that was which is responsible for the power spikes and the customer was capable of shifting the operating time of the machine from afternoon until the midday when the solar system performs optimally.

This is the way TGR Energy achieves the best results for our customers.

Take a look at the picture of the system in the above. The panels were divided between 200 east facing and 200 west facing, so the system would be at its peak in between noon and dusk because the panels are set on a 10-degree angle. The flat roof that is used in this case is advantageous, but it will need greater maintenance because of dirt build-up that happens when panels are not adequately cleaned by rain.


The most important thing to consider to consider when looking at solar power:

  • Know the electricity bill you pay.
  • Find out where power is being utilized.

Once we have identified the issue after which we can figure out the best course of action and establish a rough idea of real-time savings that you can anticipate and from where the savings are coming from. It's now a matter of finding the best solution to meet the budget and eliminate the issue for good.

Although power bills can vary as do budgets and there are plenty of other variables to think about but all of our customers expect around 20% of their annual revenue or more.

Solar may not be the most effective option for those who have large costs for power There are alternatives that are cost-effective to you. Learn the TGR Energy's Three-Way Approach or contacting us.