When your PV system loses its premium Feed-in-Tariff (FiT), the priorities and objectives for the energy you generate from your PV system will change. When a FiT is much lower than the cost of grid supplied electricity, the main aim of your PV system will change from generating and exporting as much as possible, to generating and self-consuming as much solar electricity as possible. This change in priority for the PV system means you need to consider changes to your system to ensure you continue to get the greatest financial benefit from your PV system. There are a variety of options available to achieve this and depending on your unique situation, different options will be best suited to meet your individual needs. These option plus some preliminary checks before making decisions are discussed below.
Before making your decision
Without a premium FiT, the best outcome will be to self-consume as much of your solar generated electricity as possible. However the most important thing to do before going off and changing your PV system, upgrading it or adding AC-coupled battery storage is to get some reliable information so you make the right decision; don’t waste your money. This means you need to get some basic information to understand how and when you both generate and consume electricity. There are different options tailored to meet your individuals needs.
Get Consumption and Generation data from your PV system
If your PV system has an SMA Energy Meter (either with or without a Sunny Home Manager) and has been connected to Sunny Portal you’re almost done. Your Sunny Portal plant will be able to give you information about how much energy you:
- Export to Grid
- Consume from the Grid
This will give you your self-consumption ratio (Solar Generation – Export to Grid) and your Self-Sufficiency (Self-Consume / [Self-Consume + Consume from the Grid]).
When accessing this information from Sunny Portal, the other advantages are that you can review these numbers on a month to month / year to year basis, as well as use the data to feed directly into a new or modified solar/storage design when using Sunny Design. This will help you better understand how certain options might affect your return on investment.
Get Consumption and Generation data from your Electricity Bill
For PV systems which do not have any monitoring installed, it is still possible to obtain some basic numbers for Self-Consumption and Self-Sufficiency by analysing electricity bills for the time the PV system has been installed – provided the PV system has been billed as a net FiT rather than a gross FiT. To get some simple number for Self-Consumption simply add up the total of energy which has been exported from the system to the grid by checking the period’s electricity bills. Then look at your inverter display and see what the total energy production since installation has been. Self-consumption can then be approximately calculated:
[Total Generation – Total Export]
Self-Sufficiency can be calculated using the same source materials:
[Total Generation – Total Export]
Total Purchased Electricity
Once you have some basic data, you are ready to start selecting what the best option is for your PV system now that you’ve lost your Premium FiT.
Option 1: Install Monitoring
If Self-Consumption and Self-Sufficiency cannot be determined, the lowest risk option can be to install monitoring. For SMA solutions this can, for some inverters, be as simple as adding a SMA Energy Meter while other inverters may also require a Sunny Home Manager (example shown below in the dotted black line).
Installing monitoring devices will be relatively low cost. Additionally, by installing monitoring and waiting a period of time to collect some information about your PV system and home energy consumption, the most economically appropriate option can then be selected with far greater certainty. Installing monitoring will not be a wasted investment as many of the other options of expanding, replacing or modifying a PV system including load automation or AC-coupled battery storage will either require or benefit further from this monitoring hardware.
Option 2: Add to / Expand your PV System
Adding to or expanding an existing PV system is a good low cost option which allows you to increase your self-sufficiency from the grid, without wasting the investment already made in your original PV system.
Adding a second small PV system (such as with a Sunny Boy 1.5/2.5) is a simple and low cost option. It also allows the original PV system to continue to generate a return while the second system helps further increase self-sufficiency.
Expanding might be an option where the existing system only has a small amount of PV connected to a larger capacity inverter (e.g. 1.5kW of PV panels connected to a 5kW inverter). These types of systems will generally have high self-consumption but will still draw a lot of energy from the grid. Expanding the system by adding additional strings of PV modules can be an excellent way to increase self-sufficiency for people who already have high self-consumption.
Option 3: Replace your PV System
Replacing a PV system can be a good option for systems which already have a high degree of self-consumption. Many systems coming out of a FiT only installed a 1 – 2kW system using older SMA inverters such as the Sunny Boy 1100/1700. While these systems might still be operating fine, they use older less efficient technology and are also not well suited to integrating with newer SMA platforms like Sunny Portal and SMA Energy Meter. Since the inverter is only one component of the cost of a system, it may only be a marginal difference to install 5kW compared to adding a 2.5 or 3kW system. This option will likely be more expensive though than adding to existing PV systems. When replacing a PV system, new SMA generation inverters like the Sunny Boy 5.0 are the ideal option. Not only will they help increase self-sufficiency, they are also ready to add AC-coupled battery storage and are easily compatible with SMA monitoring and control platforms through WiFi. They also come with a new service concept, Smart Connected, where SMA actively monitors the system for the customer throughout the warranty period and responds to errors or faults to better guarantee your investment.
Option 4: Re-Orientate your PV System
Re-orientating your PV system would involve changing the location of your PV array so that its energy output better matches when your home is using electricity. Re-orientating a PV array can be best suited to larger PV systems (~4-5kW) which have very low self-consumption and self-sufficiency. This would likely be a lower cost that completely replacing the PV system. Systems installed under a premium FiT were often designed to maximise energy generation (i.e. PV array oriented directed towards the equator) and maximise export to the grid. This often resulted in low self-consumption and self-sufficiency. By re-orientating the PV array, the output can be made to better match the energy use of the home. This reduces both energy exported to the grid and also energy imported from the grid. Examples of this could be to split up a North facing PV array (South Facing if you are in the Northern Hemisphere) so that it has an East facing and a West Facing PV array. An example of the output from such an array is shown below.
Option 5: Increase Self Consumption using SMA Smart Home and Load Automation
The best way to benefit from your PV system is to use the energy it generates at the time it is being generated. For larger PV systems (3-5kW) but which have low self-consumption, turning on loads during the day when your PV system is generating energy provides the best return. However it is not always easy to know when you might have spare solar electricity to use or that you are even home to be able to turn loads on or schedule them to operate. Installing an SMA Energy Meter and Sunny Home Manager on an existing SMA PV system with Webconnect capability will give you information about how your PV system will operate throughout the day to allow you to potentially schedule home appliances like a washing machine, dishwasher or clothes dryer to turn on when you know you will be generating and exporting energy. An example of the information you can see in Sunny Portal is shown below.
While installing this type of monitoring and getting the information needed to increase self-consumption is attractive to some consumers, others would like to be able to install a little more hardware and have the system just control everything itself. This is where the SMA Smart Home and Load Automation can be the best solution. The SMA Smart Home can integrate smart WiFi sockets from 3rd party suppliers and also directly communicate with smart home appliances to control them so they operate only when there is spare solar energy. Utilising the SMA Smart Home and using smart load automation both help an existing PV system to reduce the amount of solar energy exported to the grid for a low FiT, while increasing self-consumption and self-sufficiency.
Option 6: Add AC-Coupled battery storage
Adding AC-coupled battery storage is the option most people will think of first when they are considering what to do when they lose a premium FiT. You will need to remember though that the cost of batteries will likely make this the most expensive option and that as of the start of 2017, good quality batteries from reputable manufacturers can still be somewhat expensive. For systems with very low self-consumption and self-sufficiency, AC-coupled battery storage can be simply added without needed to make any changes or modifications to the PV system. The perfection solution in this case is the Sunny Boy Storage. It is designed to work with new smart High-Voltage batteries technology from leading companies like LG, Tesla and BYD. An example of how the AC-coupled Sunny Boy Storage can be added to a PV system is shown below in the dotted black line.
Since the battery is added to the system via AC-coupling, it is better able to meet your homes energy needs by supplying from both solar and battery simultaneously. With the addition of a Sunny Home Manager it is also capable of charging the battery from the grid which is especially beneficial for improving the ROI if you have a time of use electricity tariff which is high during peak periods, and very low during off-peak. These types of AC-coupled battery storage solutions are also better suited to provide blackout protection with some simple additional electrical components.
You can learn more about the Sunny Boy Storage and how it can work for you by watching this short YouTube video.
When you lose your premium FiT, the priority of your PV system will need to change from generate and export as much as possible, to generate and self-consume as much as possible. There are many different options you can chose to achieve this outcome, but it is important to make sure you do some preliminary checks to make sure you don’t invest in the wrong option. In this article, we presented 6 different options which you could use to help increase your self-consumption and self-sufficiency after losing your FiT. Make sure you consult with your local SMA specialist to help confirm which of these options might be available to you and to help chose the right SMA solution.
Scott Partlin (guest author)
I lead the Application Engineering department at SMA Australia, which provides pre-sales technical support for Residential, Commercial and Utility scale systems. I also work closely with Product Management to help refine SMA's solutions to be better suited to market requirements.
Market issues, SMA product suitability, new business opportunities, Asia Pacific Region (APAC)
Reading to my children, volunteering at my local football club, skiing, wine tasting (only good wine though)
What even my colleagues don’t know about me:
Have travelled to Nepal to deliver and install a rural hospital solar lighting aid project. Received my Gold Duke of Edinburgh’s award personally from Prince Phillip in 2004. Once spent a night lost in the wilderness on a trek because our group was reading the map upside down.