01
Use your own solar power
Every kWh you use yourself is a kWh you don't buy. It's worth exactly what you would otherwise have paid, including tariffs and VAT, not just the spot price. It's typically the largest of the four.
All subscriptionsSavings with GridZeno: Where the money can come from.
We don't promise you an amount. Instead, we explain exactly where a gain can arise, how we calculate it, and what can make it disappear.
The short answer to "How much can I save?"
In October 2026 power on our own system cost DKK 391 with GridZeno against DKK 511 with the inverter on its own: DKK 120 saved in a month. Without GridZeno is calculated with the same sun and the same consumption and the inverter in its own self-consumption mode. Your system can give more or less: the gain depends on the size of the system, whether you have a battery, when you use power, which grid company you belong to, and how much the electricity price varies. GridZeno measures and shows the actual value afterwards.
Four sourcesWhere the gain
Where the gain
can come from.
The gain comes from four smaller sources, which pull in different directions depending on your system.
02
Shift consumption in time
Charge the battery when power is cheap, and use it when power is expensive. The gain is the difference between the two prices, minus what the battery loses along the way.
Smart and Pro03
Sell at the right times
Surplus that can't be used or stored is better sold at a high price than a low one. GridZeno saves room in the battery for the surplus that's paid worst, and sells what is paid well.
Smart and Pro04
Avoid paying to sell
At negative prices it costs you money to send power out onto the grid. Then it's better to charge the battery or stop selling. It happens in the middle of the day and is hard to catch yourself.
Smart and ProDo the maths
What a price spread is worth
If you move power from the most expensive hours of the day to the cheapest, the gain is the difference between the two prices, minus what the battery loses along the way. Adjust the numbers and see the calculation.
What you can actually use, not the battery's rating plate.
Between the most expensive and the cheapest hours, after tariffs and VAT.
Not every day has a spread worth trading on.
| 10.0 kWh × 1.00 DKK | 10.00 DKK |
|---|---|
| After battery losses (90 % returned) | 9.00 DKK a day |
| Over 250 days | 2,250 DKK |
With those numbers, the calculation would cover a Pro subscription (948 DKK a year) 2.4 times over. In the first year the dongle and shipping come on top, 598 DKK, so the first year costs 1,546 DKK
This is plain arithmetic on the numbers you have chosen yourself, not a calculation for your system and not a promise of a saving. The numbers don't take into account that the battery is often already partly filled by the sun, that your inverter has a limit on how fast it can charge, or that some days have no spread to trade on at all.
Put it in perspectiveA price spread is
A price spread is
not a saving
in itself.
The calculation above shows the ceiling: the best possible return from one battery in one day. Reality is lower, and here are the reasons:
- The battery is rarely completely empty when the cheap period starts. The sun has often filled some of it already, and you would have had that energy anyway.
- The inverter has a limit on how fast it can charge. If the cheap period is short, you don't manage to fill the whole battery.
- Every cycle causes wear. That's why the strategy "Preserve the battery" exists. It gives less in the short term and a longer lifetime.
- On some days the price is almost flat. There's nothing to gain, however good the control is.
That's why GridZeno's value figure is based on what actually happened: what you really bought and sold, at what times, at what real prices.
How we calculateThe four amounts
The four amounts
in your report.
Every report contains four figures. None of them is a prediction. They all describe something that has already happened.
- The value of your solar production
- Your production multiplied by the buying price that applied in that exact quarter hour. In other words: what it would have cost to buy the same power instead.
- Earnings from export
- What you have sold, multiplied by the selling price that applied. Real money you have already received.
- The value of imported power
- Your import multiplied by the buying price. What you have actually spent on buying power.
- The value of timing
- The difference between what your import actually cost and what the same amount would have cost at the period's average price, plus the value of the import the battery avoided completely.
Charging is valued as if it had been bought from the grid, even when it came from the sun. This is a deliberately cautious assumption: it can only make the battery's value look smaller than it is, never larger.
Be realisticWhen it
When it
doesn't pay off.
You don't have a battery
Then there's no storage to move power around with. You can still get a good overview and stop selling at negative prices, but the two biggest gains need a battery. Here Light or Smart is the honest choice.
Your consumption is already well timed
If you use most of your power in the middle of the day while the sun is shining, you have already taken the biggest gain. Then there's less left for the automatic control to gain.
Your system doesn't support control
Some inverters can't be controlled in the ways that are needed. So check compatibility to see what your inverter can do.
What GridZeno itself costs
The dongle costs DKK 549 as a one-off payment. Light is free. Smart costs 39 DKK a month, Pro 79 DKK, that is 468 or 948 DKK a year. In the first year the dongle and shipping come on top, 598 DKK, so the first year is 1,066 or 1,546 DKK. That's the threshold your gain has to pass before the subscription pays for itself. If you can't see that it holds up for your system, choose a smaller subscription. You can switch at any time.
No figures on this page are an offer or a guarantee. GridZeno isn't financial advice. You don't have to take the calculation on trust: you have 100 days' free right of return on the dongle. See prices and terms of sale.
It starts with your systemReady for cheaper
Check your system Ready for cheaper
power?
Check whether your inverter fits, and let the plan charge the battery and sell power in the right quarter hours.