Grid congestion? No problem for solar panels!

In the Netherlands, we can count ourselves lucky to have one of the most reliable electricity grids in the world. Staggering amounts of cables are neatly stored in the ground all over our densely populated country and they almost always ensure a flawless transport of electricity. In order to maintain that beautiful grid, the grid operators are constantly busy with maintenance and expansion, digging trenches and putting up electricity pylons and transformer stations. But lately they've been having increasing difficulty in keeping up, which has led to so-called 'grid congestion'.

In the grid congestion map of Netbeheer Nederland you can see where the problems are for consumption (left) and feed-in (right). Red = grid is saturated

Everything electric

The causes of these problems are well known: on the one hand, we are all using more and more electricity, and on the other hand, solar panels and wind turbines are pushing more and more electricity into the grid all over the country. The reason we're using more and more electricity is because electricity is a great way to heat our homes, fuel our cars and prepare our meals. Thanks to all this electricity, we need less and less gas and oil for these things, which means we can prevent earthquakes in Groningen, we don't have to import gas fom Russia, and we can help to combat climate change. The more electricity, the better. This will ultimately allow us to largely dismantle the existing gas network, which will save a lot of money on its maintenance.

But before that happens, the grid operators have a lot of work to do to increase the absorption and delivery capacity of our network. Although a lot of money and energy is being invested in it, unfortunately it does mean that in some cases a local grid may not be ready in time to accept extra demand or feed-in. When that happens, the grid operators are forced to tell customers that they cannot get an increase in the size of their electricity connection, or that they are not allowed to feed back into the grid. The latter does not happen so much to small consumers (homes or small businesses), but it does happen with larger grid connections for businesses or apartment buildings.

Solar production precisely adjusted to consumption

Fortunately, there are solutions for such situations! For example, in places where no feed-in is possible, solar inverters can be configured in such a way that they don't produce more solar power on the roof than what is simultaneously consumed in the building. All that's required to do this, is a measuring device at the grid connection point that controls the inverter(s). As soon as power threatens to flow from the building into the grid, the output power of the inverters is ramped down very quickly. With this rapid regulation, the system can perfectly adjust the production of solar power to consumption.

Graphs of yield and consumption of electricity. On the left a system without feed-in limitation: the yellow part (below the line) is the surplus that is fed back into the grid, green = the electricity that is consumed in the building. On the right a system with feed-in limitation: there is no surplus, because generation follows consumption exactly. Red = the consumption from the grid.

Zonnefabriek has built a number of such installations. They work perfectly and require hardly any additional costs. Of course, some potential solar power is ‘wasted’, but as long as the size of the PV system is in the same order of magnitude as the power demand in the building, these types of systems are still a very profitable investment. This way, green power can still be generated in places where feed-in is not permitted.

Batteries create extra space

We can also go a step further by adding batteries. If we do that, the surplus power would not be wasted, instead we could store it for later use. Although adding batteries makes such a system a lot more expensive, it also allows for more solar panels to be installed.

Batteries can solve not only the problems with feed-in, but also those with the consumption of power. If a company needs to use more power, but cannot get a larger mains connection from the grid operator because of grid congestion, then batteries can provide extra space. Strictly speaking, you don't even need solar panels for this. The batteries can be charged either with solar power, or with mains power at times when there is little consumption, for example at night. When power-hungry equipment is then switched on during the day, the batteries kick in. Suppose that due to the limitation of the mains connection, a maximum of 200 kilowatts of power can be drawn from the grid, while 250 kW is temporarily required. A system with batteries could then supply those extra 50 kW. In this way, businesses still have the opportunity to expand, even if they can't (for the time being) get a larger connection from the grid operator.

The batteries for larger systems consist of metal cabinets with modules that are placed in a separate room, or in a container outside the building (source: SMA)

Zonnefabriek can help calculate what products a business or an apartment building needs to build such a system. Batteries are, as we mentioned, not cheap, so it's important to figure out exactly what the minimum battery capacity is with which everything will still work well. With the systems we install, future expansion will always remain possible. Businesses can also receive financial assistance for battery systems in the form of the EIA (Energy Investment Allowance). You can find more information about this on the website of the RVO (Rijksdienst voor Ondernemend Nederland, Netherlands Enterprise Agency).

Smart inverters and battery systems can contribute to solving the problems of our electricity grid in a simple and cost-effective way. Zonnefabriek would be happy to help with applications for your specific situation: if you think we can help, we would love to hear from you!