Nowadays, the major conferences on solar energy are increasingly concerned with storing solar energy: How can we best temporarily store the energy from the solar panels until the moment we need it? Should we already connect the solar panels to batteries?

Solar energy is produced when the sun shines, everyone knows that. But that is not necessarily the same time when the energy is needed. Until now, the difference in supply and demand has been easily compensated by the large power plants on the grid. But as more and more solar panels are installed, it becomes more important to look for solutions for temporary energy storage, such as batteries/accumulators. 

Batteries allow you to achieve a greater degree of self-sufficiency. When you are not at home during the day but are at home in the evening after sunset, you can ensure that the energy generated during the day is stored in batteries, to be made available again in the evening for your consumer appliances.

What is needed for solar energy storage?

First of all, you will of course need batteries (accumulators). The more batteries you have, the more energy you can store. The energy that is stored in a battery must be made available again in the grid when you want it. This requires a battery inverter, which converts the direct current from the battery (DC current) into the alternating current on the grid (AC current).

Batteries are expensive, and their lifespan is highly dependent on how they are charged and discharged. The more ‘cycles’ (times of charging and discharging) they undergo, the faster they lose capacity. That is why it is important to use the batteries smartly: only charge when it is useful (a lot of sun in the coming period and little consumption in the short term) and only supply back to the grid at the best times (a lot of energy is used). expected and the sun is gone for now). This requires a system with smart control that takes into account, for example, the weather forecast.

How much does it cost to store solar energy?

The costs of such systems are highly dependent on the desired capacity. Batteries are the most expensive part, and the more batteries you put in, the more expensive it gets. Furthermore, the battery inverters are also fairly expensive: for an SMA battery inverter, you pay almost double what a solar inverter of the same power costs. The products for the smart control of the system are a lot cheaper, but also come down to several hundred euros. And finally, there are installation costs involved.

Some manufacturers offer ‘hybrid’ inverters; these are devices that operate both the solar panels and the batteries on the DC side. Although this may lower the costs of the system, on the other hand, such a system limits the possibilities for future expansion; during installation, the amount of batteries is immediately fixed for many years. The handy thing about a so-called ‘AC-coupled’ system is that the batteries can only be added to an existing PV installation at a later time.

Is it worth the investment?

The netting rule applies in Australia for now and for the coming years (at least until 2023 ), which means that the public grid actually functions as a buffer for people with solar panels. Excess energy produced flows to the grid and is settled one-to-one with the energy that is consumed. That is why there is currently no economic added value to installing batteries in the house.

There is currently a lot of investment worldwide in new, and hopefully cheaper, battery technology. Hopefully, by the time adjustments are made to the netting scheme, the costs of the battery will be a lot lower than today. That is why pieces of advice not to invest in storage capacity for the time being.  

Another article on this blog that may interests you:

Batteries, The Rechargeable