How to read your electricity bill with solar

So you’ve had a solar system installed and are still receiving power bills higher than expected with what seems to be very little solar credit… is your solar system not working efficiently?

There are 3 main factors to consider:

1. What is your daily usage? (The power you are buying from the retailer on a daily basis –

usually indicated on the front page of your bill).

2. How much solar power are you sending back to the electricity grid? (The kilowatt hours (kWh) you are credited for

by your electricity retailer – usually indicated on the ‘charges, calculation and usage’ section on your bill – often written as ‘solar contribution’ or ‘solar feed in’).

3. What is your solar system’s daily production? (Checking your solar inverter is the only way to determine this information).

Firstly, you should check how many kWh you have used in the past compared with now, using previous and current bills.

Your ‘average daily usage’ in kWh should be on the front of your electricity bill. If your electricity usage is fairly high, you have increased your electricity usage or your retailer has increased their charges, you will pay more when your electricity bill arrives. It is often forgotten that in the winter months we tend to use more electricity due to the amplified use of heaters, electric blankets etc; whilst the solar system often produces less due to reduced daylight hours and increased shading on the panels. In the summer however, you may have air conditioners, fans and pool pumps running more regularly yet the sunlight hours are also extended which usually helps to compensate for these additional expenditures. The solar credits (as outlined on your electricity bill) indicate the money you have been paid for solar power in kWh that you have NOT used and effectively sent back to the electricity grid. Those figures are not what your solar system has produced in total for that billing cycle. (The only way of determining your solar system production is by checking the readings on the display screen of your inverter). To determine how much solar power you do not use and send back to the grid each day – you should divide the amount of kWh sent back, by the billing period in days.

E.g. Bill Period = 90 days

Solar Contribution = 400kWh

400kW / 90 days = 4.4kWh per day

Depending on the brand of inverter you have installed, your inverter should display a “Today” reading or something similar. This reading indicates how many watts your system has produced since it turned on that day. By deciphering your average daily kWh usage from your electricity bill as explained above and taking the “Today” reading from your inverter, you will be able to obtain an understanding of how much power you use versus how much power your system produces and hence an approximate amount you can expect to be billed for. (Remembering that whatever power is used during the day while the system is performing, the solar production will power your usage first, with any excess production sent back to the grid and credited to you at the feed-in tariff rate you have signed up for).

This is why if you are receiving a feed-in tariff lower than the rate you pay for power (Approx. 30c) it is in your best interest to change your energy consumption habits and try to use your electricity throughout the day when the solar power is indicating peak production (10am-3pm on clear sunny days). Remembering also that your retailer will charge you a ‘service charge’ – these vary and can be as high as $150 per quarter in NSW.

There are also numerous other factors to consider with system underperformance aside from seasonal weather conditions. These include:

• Shade

• Roof orientation/pitch

• Soiled panels (bird/bat droppings, leaves, dust etc.) or;

• A system or inverter fault

We recommend that you monitor your solar system regularly by checking for a green light and readings displayed on your inverter screen (during daylight hours – the system will power itself off at the end of the day). If there is a grid failure or an error with the inverter it can go unnoticed for weeks or even months if not checked regularly, meaning that your system will not be generating electricity and therefore not contributing to your electricity bills. The sooner you notice anything unusual or if there is a fault light or message on the display the sooner the issue can be addressed and we can help get you back up and running. SAE Group also offers full system maintenance checks – please contact our office for more information on this service and how it could benefit you.

If you do feel as though your system may be under producing, or you still have some questions after reading this document, please don’t hesitate to contact our office on 1300 18 20 50.

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