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5 min Reading time The suppliers of battery systems (including Zonnefabriek) may claim that you benefit from your batteries, but how can you be sure that this is really the case? We look at the ways in which you can now and in the future keep track of the operation and benefit of the batteries.
Real financial benefit from a battery only happens if you take out a dynamic energy contract. In that case, the battery charges either with your own solar power or with cheap electricity at times when the exchange price is low. The delivery back ideally happens when the exchange price is high. On Sunny Portal it looks like this:
Figure 1: Generation and consumption of a system with batteries and the Energy Maximizer. The dotted line shows the battery charge. The battery charges from 0 to 100% every day and delivers back to the grid at the most favorable moments. This way the battery is utilized to the maximum.
Here we see the battery charge that rises from 0% to 100% every day, only to drop back to 0% later: That's perfect, because this way the capacity is fully utilized. We also see that the delivery back mainly happens during the evening and morning peak hours. These are precisely the moments when the electricity price is highest. This installation therefore benefits maximally from the battery in combination with dynamic tariffs. The Energy Maximizer plays an important role in this.
Compare it with the installation below. In this system there is no Energy Maximizer, but there is the Sunny Home Manager that controls things. Here we see that the battery does charge with solar power but that it never actually runs empty. This is because it is summer, and therefore there is a lot of generation and relatively little consumption. These people also benefit from their batteries (because they don't have to purchase any kWh of electricity from the grid all summer), but less than the people in the first example.
Figure 2: Generation and consumption of a system where the Sunny Home Manager is in charge. The battery is not fully utilized here, which means slightly less benefit can be obtained from the system.
The best thing would be if we could see in the portal or in the app the amount that was earned on that day or in that week or month. In the SMA Energy App this is currently not yet possible. There is indeed a section 'your savings' at the very bottom of the app's dashboard screen, but this is currently only about CO2 savings and not about money. SMA has told us that they will soon also want to show the financial savings in the SMA Energy App.
For people with a SunPower battery in combination with a dynamic energy contract from Frank Energie, it is already fairly visible how much the battery yields. In the Frank Energie app you can see how much you earn each day from 'smart trading'. However, it sometimes takes some puzzling to understand exactly how they arrive at that amount.
The profit comes partly from the solar panels and partly from the batteries; it is not always easy to separate the two. The system actually needs to look at what you would have paid if you had neither solar panels nor batteries, then at what you would have paid if you only had panels and no battery, and finally at what you actually paid.
Moreover, from next year the calculation will be different. When the net metering scheme stops, having only solar panels and no battery becomes considerably less profitable than today: delivery back at sunny moments will then yield almost nothing. Storage in batteries then actually becomes a must to make your solar panels still somewhat profitable. The relative benefit of your battery increases significantly at that point. But delivering back from the battery to the grid could well become considerably less interesting: even at the moments with the highest electricity price, each kWh delivered back will yield you less than is the case today. That's why we advise our customers not to choose the largest possible battery, but one that is tailored to your daily consumption.
Batteries provide financial benefits for those who have solar panels, but they also require a considerable investment. That's why an objective view of the actual return is important. Monitoring the yield graphs on an app or in the portal helps with this, although there is certainly still room for improvement. And we need to be sharp about which part of the yield can be attributed exactly to which component of your installation. Zonnefabriek strives for as much clarity as possible in this: we are happy to help you if there are questions and will inform you as quickly as possible when new options become available.
