Over the past few weeks, Elering seminars and the media have been talking about energy so much that it is starting to feel like a campaign. My guess is that someone is preparing the ground for the next price increase. But there was one question I never heard.
0 kWh
that's how much my home has bought from the grid since 10 April. A battery, solar panels and a hybrid inverter do the rest. The same setup could work for an entire substation.
How many missiles or drones would it take to knock out Estonia's power supply?
That is the question I wanted to ask at the seminar. The answer is uncomfortable: not many.
Our generation has historically sat near the border, because that is where the oil shale plants were. From there, power travels over 330 kV lines to Tallinn, where most of it is consumed. Everything hangs on a few points. Take out one big substation and the whole of Võru parish goes dark. Power could be generated there too. But every house is waiting for what comes down the line.
I recently talked this through with an acquaintance who works at an energy aggregator. His answer was correct and depressing: you need a grid that can run in pieces on its own. But that takes enormous investment and generation placed where the consumption is. Twenty, thirty years.
I don't think we need to wait that long.
The panels and batteries are already here. What's missing is the boundary
Estonia is covered in solar panels. More batteries arrive every month. The problem isn't the hardware. The problem is that every house is its own island, and an ordinary house can't do anything without the grid.
If we want lots of small islands that can survive on their own, where do we draw the line? A single house is too small. A municipality is too big. I would draw it at the substation: one transformer and the houses connected to it. I wrote about this in my Rätsepa energy co-op post too.
The grid operator becomes the billing agent, not the owner
My model is simple. An energy co-op forms behind the substation and runs the grid behind it itself. Elektrilevi's metering ends at the substation. Beyond that it only provides billing: it measures how much each house consumed and how much it fed back. Inside the co-op there is no longer a network service or electricity sale in Elektrilevi's sense.
What happens next? The co-op installs a decent-sized battery straight away. Not for security, but because the spreadsheet says so. Buy cheap power at substation level, charge the battery when prices are low, use it when they're high. My estimate is that it pays for itself in three to five years. If the houses already have panels, those charge the same battery. If someone has built a solar park nearby, they run a direct line to it.
And here is what turns this into security. When the national grid goes down, a substation like that keeps ticking along on its batteries for at least a day. Security comes for free, because everyone simply did what made financial sense for them.
Does it work technically? It works at my house
My grid connection runs into a hybrid inverter. Behind the inverter are my loads, a battery and solar panels. There is also a generator input, where you could plug in a diesel generator.
If the grid disappears, everything switches to the panels and the battery. I don't have to flip anything. The inverter does it on its own.
A month later I bought an electric car, because now there was a reason to. Every charge at home has come from the sun.
But half the houses have nothing
That was my acquaintance's strongest objection, and he is right. Take any substation. Say there are a hundred households behind it and twenty of them have panels and a battery. When the grid goes down, twenty home inverters can't keep a whole village running. And the houses without anything can't do anything on their own.
The solution is a device with inverter capabilities between the substation and the local network. It detects that the grid frequency is gone and starts generating the frequency itself. It doesn't choose whom to supply; it supplies everyone behind that substation. The co-op decides how big a battery to install as its own investment in energy security.
Apartment associations are an easy example, but the biggest win is in the countryside, where a single line fault or a single drone can leave a whole parish in the dark.
Where's the catch? In taxes, not physics
Say there are ten consumers behind a substation and half of them produce. Today the producer sells power to the neighbour without VAT, and a margin and a balancing fee are deducted on top. The neighbour then pays network fees, excise duty, balancing fees, the seller's margin and finally VAT as well, a form of double taxation. The producer has no reason at all to sell to the neighbour.
Take your electricity bill and see how much of it is the electricity itself. For me it's about a quarter. The rest is fees and taxes you can barely count.
If all of that disappears inside the substation, the scheme suddenly pays off for everyone. That is a political decision, not a technical one. The state and the grid operator have to accept that they no longer earn on power that moves inside the substation.
What you do differently now
If you are buying a battery or an inverter, ask the seller one question: does it work when the grid is down? A standard grid-tied inverter shuts off during a power cut, even when the sun is shining.
And when you next hear about energy security at a seminar, ask the question I wanted to ask: how many drones would it take? If the answer is "not many", the next question is why we don't let substations look after themselves.
Who owns the grid behind the substation?
In new residential developments, local municipalities have required developers to build the power lines and then hand them over to Elektrilevi for free. So the real owners there are the owners of the properties behind the substation, whose assets the state has effectively confiscated.
Does Elektrilevi do the grid work today? No, subcontractors do. Elektrilevi is a project company, and a very expensive one. There are no engineers left in its management, only lawyers.
Elektrilevi's service comes down to reading meters and sending the readings to Elering's data hub. It doesn't even do the billing; that is beyond it. The invoices come from Enefit instead.
How should a co-op use the grid behind its substation: lease it or take it over? How much would the state lose in taxes? I don't have answers to those questions yet. But none of them is a question of physics.