by Jonathon Dore and Daniel Tam
When you decide to add solar to your home, switching on your system is just the start of your solar journey. By learning how your household uses energy and when (and how much) solar your produce, you can make simple changes to really reduce your dependence on the electricity grid, to save even more.
Let's look at how to assess your energy consumption and understand what you can do to optimise it.
Grid dependence is the proportion of your energy use that comes from the grid. A home without solar energy is 100% grid-dependent. An off-grid home or a home that gets all of its energy from solar is 0% grid-dependent.
Self-consumption is the proportion of your energy use that comes from your solar system. Solar energy that is not used straight away or stored in a battery is exported to the grid.
By reducing your grid dependence, you pay less for energy and reduce greenhouse gas emissions. By increasing your solar self-consumption, you make the most of your investment and your system pays itself back sooner in savings.
Most actions you take to reduce your grid dependence will also increase your self-consumption, for example shifting your appliance usage to daytime, or installing a battery system. But if your self-consumption is already close to 100%, then the only way to reduce your grid-dependence is to install a larger solar system or use less grid electricity. That’s why it’s important to measure both of these numbers.
A typical Solar Analytics user has a grid dependence of approximately 74% and a self-consumption of approximately 45%.
For now, we’ll assume your self-consumption and grid-dependence are somewhere in the middle like this and explore your options to reduce grid-dependence.
Why should I reduce my Grid Dependence?
Most solar households receive only a small reimbursement, or feed-in tariff, for any solar energy exported to the grid. Depending on the location and retail contract, households generally receive around 6-12c/kWh, but can end up paying up to 9 times that for purchased electricity depending on the time of day. The largest economic returns on your solar investment are going to come from reducing the amount of energy you purchase from the grid, rather than the revenue generated by sending your solar energy back to it.
How do I reduce my Grid Dependence?
Get to know your Consumption Profile
Let’s take a closer look at what a consumption profile might look like over the course of a day.
Solar Analytics user in Athol, NSW
Here we have a relatively typical consumption profile. There is a moderate spike in the mornings when the occupants wake up and leave for work or school, heavy afternoon/evening consumption as they return home, turn on the air-conditioning/heating and engage with other electrical appliances, and minimal consumption elsewhere.
Many households may have a consumption profile that looks completely different to this. If you are retired or work at home, then it’s likely that your daytime consumption makes up a greater proportion of your energy use than this. Even for the same household, the profile can look completely different on different days of the week. Make sure you look back through different days on the Consumption page of your Solar Analytics Dashboard to get a good feel for your usage patterns.
The key to reducing your grid dependence is in understanding how your consumption profile varies throughout the day, different days of the week, and even different seasons of the year.
Get to know your Solar Generation Profile
Now that we can see how much is being consumed, and at what times this is occurring we can apply this information to get the most from our solar systems.
Solar systems produce a curved output that follows the rise and fall of the sun during the day. This profile also varies throughout different times of the year.
In order to reduce your grid dependence, it is essential to shift your energy use so that it uses your solar energy and offsets the amount of electricity purchased from the grid at other times of the day.
Combining your solar generation profile with your earlier consumption profile, we can see a significant portion of spare solar energy remains during the middle of the day. This site has a self-consumption of only 23%, with the remaining 77% being exported back to the grid.
Understand your Appliance Usage
But how can you actually make use of this spare solar energy? The answer comes down to understanding what your consumption profile is made of. It is in fact the combination of all of your household appliances. Your Solar Analytics monitoring can monitor at least one individual sub-circuit within your home, and with multiple Solar Smart Monitors, or our model with the six current transformer (CT) clamps, you can monitor more.
Monitoring individual circuits in your home can help identify which appliances add the greatest contribution to your total energy consumption.
For each appliance it is useful to ask two questions in order to help you better manage your household energy usage:
Is it Flexible?
This depends on whether the appliance is performing a function that is time-specific for you. For example, watching your TV is something you generally only want to do while you are home. However, you can generally run your dishwasher at any time of the day, as long as it’s run regularly enough to give you clean dishes when you need them. For these reasons, a TV is something we might refer to as an inflexible load, and a dishwasher is something that might be referred to as a flexible load.
Is it Essential?
This depends on whether this is an appliance that is providing a vital function to meet your needs, such as a washing machine to give you clean clothes or lights to allow you to see. Or perhaps it’s not essential, but just nice to have. Heat lamps in the bathroom might not be essential but they’re very helpful on a winter morning. Everyone needs to find their own balance in cost and comfort.
Once you have answered these two questions, you can now follow a simple process to optimise your household energy consumption.
1. Schedule Flexible and Essential loads to run during the day using your solar energy.
Try switching an appliance such as the dishwasher on as you leave for work, instead of purchasing power from the grid during the evenings.
This is commonly called “load shifting”, which refers to the scheduling of flexible loads and appliances to make use of solar energy.
Using our example we can see what it might look like when a load is moved from the evening time to make use of the solar energy during the day. In this case the solar energy consumed on site has increased from 23% to 57%.
2. Reduce the use of Inflexible or Non-Essential loads.
Try hanging the clothes outside instead of running the clothes-dryer, turning off computers and entertainment systems at the power point to reduce standby power, avoid running the heating or cooling while the windows are open or avoid leaving lights or fans on in an empty room.
3. Explore alternative options for Inflexible and Essential loads.
Consider reducing the water pressure in the shower or putting a lid on the cooking pot and turning the heat down. If the kids have left the nest, perhaps you could downsize your refrigerator. Install LED lighting and appliances with good energy ratings. Reduce heating and cooling requirements by patching up gaps in window frames, using draught-stoppers under doors, installing ceiling and wall insulation and double-glazed windows.
Maybe you don’t want to give up using your home entertainment system in the evenings, and let’s face it who does? The answer is, that’s perfectly okay! There’s no right number for grid-dependence. It’s all about your goals and your control
Give me more Tech!
Is your Solar Analytics Dashboard making you more excited about how technology can help your reduce your energy bills and carbon footprint? Perhaps it’s time to dive in further with devices to control your appliances.
While behavioural changes are the most sensible and economic place to start, only so much can be achieved with the way you use energy. With the increasing digitalisation of everyday appliances, many are becoming more easily controllable, and with this comes the ability to further manipulate the times at which we consume energy. This can be done in several ways:
1. Built-in remote functionality in the appliance, such as a smart air-conditioner that can be switched on and off from your mobile phone.
2. Remote functionality built into a smart power socket, that sits between the powerpoint and your appliance. This is just like turning the appliance on and off at the plug, but you can do it from anywhere.
3. Programmable appliances or smart power sockets. This is like the two previous options, but you set the times you want it to run in advance.
4. Smart solar diverters. These are devices which measure when you have excess solar and automatically switch on flexible loads like hot-water heating or pool pump.
Solar Analytics is exploring ways to integrate with devices such as these to help you take the next steps in energy management. But if you try some of them in the meantime, get in touch and let us know what worked for you.
If you’ve exhausted your options in load-shifting, then a battery system can do the heavy-shifting for you. Storing your excess solar during the day for use at night-time or on cloudy days is a great way to increase your self-consumption and reduce grid dependence. Right now, the savings will make up for the battery cost for just a small proportion of households. Check out the battery estimator on your Solar Analytics Dashboard to see if you are among those households that a battery makes economic makes sense for, and to find the right size battery for you. Perhaps cost is not your main motivator for grid independence; maybe you’d just rather give your money to a battery company than an energy retailer. But keep in mind that a battery is not yet necessary for environmental benefit. If you’re exporting your solar, it’s being used by someone else instead of fossil fuel energy. So if your motivation is environmental, then perhaps consider more solar and/or green power options.
Add or move solar panels
If you have low consumption in the middle of the day, but high consumption in the afternoon, then you could consider adding or moving some panels to a west-facing part of your roof. This will mean more power in the afternoon/early evening hours since solar panels produce most power when the sun is shining directly at them. You might also consider moving panels if they are getting significant shading from trees or buildings, which prevents them working at optimum power.
If your self-consumption is already close to 100%, then a larger system will allow you to reduce your grid dependence, but if your self-consumption is low, then adding more panels will just increase the amount of electricity you export back to the grid.
... check out Part 2 of this article coming soon. We will share more detail on knowing your limits and limitations.