[1] There is a price for the first 50 units you consume, then a higher price for the next 150 units, etc. Similar system to income taxes.
Alternatively it's also practical for such solar situations to bill for market rate price of the energy in each 15 minute chunk separately; this doesn't correctly attribute transformer and other transmission equipment expenses between solar houses and non-solar houses, but it's still handling the grid tie solar load on the grid's power plants during periods of very little sun.
What an interesting metric. Wouldn't even a very cheap and small battery (definitely small enough to keep inside an appartment) provide enough smoothing to, like, halve this peak number? You could rig it to not even output energy until you are beyond the current year's peak usage... How much money would you save this way?
I just feel this number is so prone to small mistakes (grandma plugs in the wrong things at the wrong times) and hacks (like the above) that the relationship between users' reward/punishment and the grid's health seems wildly disproportionate.
> market rate price of the energy in each 15 minute chunk separately
I am currently on a plan with 5 minute market rates, can buy and sell in (sell prices can go negative - as can buy, actually), all automated. At least I feel we am working with the grid, not against it, and we make a small net profit (before depreciation).
It's still much closer to the real costs for the grid operator than $/kWh. The fundamental problem that rooftop solar has revealed is that people think they are paying for the electricity, but they are not. Electricity is dirt cheap. Most of what they are paying for is the maintenance of the grid, and simple usage based billing crushes the system because of freeloader problem once rooftop solar is added.
Long term, the likely thing you pay for will be the size of the main fuse that connects you to the grid. Because that's the thing that scales with the costs you impose on the operator.
Of course, how does the electricity company determine which user was first in this situation. A tariff that depends on the order of connection may not be practical for domestic situations, although it may be OK for very large users, e.g. factories, data-centres.
Using fuse size seems a more reasonable and fair proxy for cost, assuming the same load patterns as the rest of the users. Then again, consumers with EVs might argue that their load pattern is different to the average user (e.g. filling up with off-peak electricity). Also consumers with air conditioning might argue for special treatment given their usage correlates with solar output (except where it does not).
Punishing a mere "large enough to not worry about popping it" fuse by billing shared infrastructure based on it (not just billing the stub line from the main in the street to the fuse/meter box in one's home in relation to what wire gauge is needed based on the fuse choosen) is pretty stifling. If e.g. your furnace fails in the middle of the winter and the repair guy tells you it needs replacing, you might want to get some space heaters and run them for a few days until your actually-wanted new furnace/heatpump/whatever can get delivered, instead of having to get installed whatever the HVAC guy has in the local storage, because if you wait more than on the order of 12 hours, you'll start to get frost damage from pipes and such.
Having to be beholden to an electricity company having time to upgrade your fuses on such short notice so that you can plug in the space heaters without blowing them might be a problem. But paying say 300 bucks extra because you did that for like 3 days or so would easily be cheaper than the cost of temporarily installing an available loan furnace and then having to remove it again to make way for the actually-wanted one.
They do though bill you if you make them dig the street up to say pull a medium voltage line into your factory that previously just got low voltage from a shared street transformer, but now that you've plans to use a lot more, you'd need the higher feed. Then they bill you and if within like 10 years or so someone else orders service that can piggyback on what capex you paid for, then you'd get a proportional refund from them having to pay off part of your share. But that's not for just getting normal basic electric service to a normal residential building in a city, that's for building a new farmhouse on the other end of some field where there never was electricity, or for getting unusual service that wouldn't be in the street if you didn't request it. Merely sizing the transformers/substations to handle the aggregate current of the users attached is not typically handled by the above mechanism, especially because it only covers initial buildout.
Like namibj mentioned, this does not apply for residential contracts.
The 15 minute chunks are due to the German and much of the European grid market being in that chunk size.
The steps are pretty coarse - on my rate plan there are just 3 steps: 0-10 kW, 11-15 kW, 15 kW+. You're not going to surpass peak 10 kW in an apartment anyway.
The grid becomes an insurance policy. In that case it is justified to ask for the insured party to pay their share of the system costs; both an energy fee and transmission/distribution/generation capacity fee.
I’ve only ever rented though. Are connection fees something that homeworkers think about?
Possibly we will have to see changes to account for this sort of stuff at a more granular level, as the grid becomes more dynamic. But, that’s a future we should be actively looking to design for, as the energy supply mix is going to change whatever anybody thinks about that. Can’t beat energy falling from the sky, on price…
My monthly electricity bill in Sweden, averaged over a year to 1600KWh/month, is approximately €90 production, €50 transmission fee, €25 fixed connection-size fee (25A, 400V), €70 national electricity tax and €50 VAT for a total of €285/month.
We'll be moved to yearly-peak-based transmission tariff in 2027 (European law), but for now I don't need to worry about plugging in the car to chargeon cold days or taking shower when someone is cooking.
It basically pays off the grid stability provision bids for fast-response power, and the transmission itself.
It'd likely be helpful if the peak part could be regulated in a way that's more condusive to match the actual impact you create on transformer sizing, not the worst-case impact you might have. Because there's a difference between a mostly-uncorrelated peak of shower+cooking vs. the car+cold day, because your neighbours don't shower the same time, but the several hours of charging do often overlap and the cold is the same across a neighbourhood that shares a local substation.
But yeah, for the most part, transformer size isn't that large of a contributor to overall electricity provision expenses, so I don't expect that to be a significant problem by that 2027 law.