For residential customers, testing usually takes only a few days. If it takes longer, it may be due to incorrect installation, the inverter having an incorrect firmware version, or export/import limits set on the system.

No. When Fever’s optimization is active, we control the battery. Our optimization creates a schedule designed to give you the maximum possible financial value, and therefore it’s not possible to use your own manual logic at the same time.

When we validate a battery, we test how much power it can deliver stably over 5–15 minutes. Many batteries that have been used for a while can no longer maintain their original maximum power long enough for us to reliably offer it to Svenska

Kraftnät. Therefore, the registered power may be slightly lower than expected.

To get the best possible results for your customer, ask them to check that:

First hours live: The first day after an installation and until midnight, Fever optimisation will not do anything. Our model is observing and learning the constraint of the system.

First 2 days live: Fever is getting to know the system and the home. During these first days, the optimisation is based on general rules and logic.

After 2–3 days live: Fever has now started to learn how this specific home works. The optimisation becomes more adapted to the household. It’s normal that the customer notices that the system starts behaving a bit differently.

After 7 days live: After one week, the optimisation is more tailored to the home. The customer may notice further changes in how the system runs and this is expected. After the first week, the system will continue to adjust and improve over time as seasons and consumption patterns change.

It’s completely normal if your battery doesn’t charge to 100%. Fever controls your battery so that it can participate in different support markets to balance the grid. In some of them, you get paid just for being ready to support the grid — either by charging or discharging.

To make sure there is room both to charge and to discharge when the grid needs help, we keep your battery at a level between about 30–70%. It may look like the battery isn’t doing anything, but in reality, you’re making money by being available when the grid needs help.
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Our optimization always compares alternatives and chooses the one that gives you the most money in the end.

Part of your battery can participate every hour in Svenska Kraftnät’s balancing market, where you earn money by being ready to charge or discharge. You get paid for being ready whether Svenska Kraftnät actually needs your help or not.
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Since the income from these balancing markets is favorable for you, the control ensures that part of your battery is always ready. Another advantage of this control is that the lifespan of your battery is extended compared to charging/discharging heavily every day.

See answer of "Why doesn’t Fever charge my battery to 100%?". However, if we have several sites with dynamic prices all with constant state of charge for a few days. Please contact Fever Energy.

Your control system ensures every day that the best possible schedule for your battery is created. This is based on current electricity prices, grid fees, predicted solar production, predicted consumption, taxes, and tax subsidies. You can therefore expect the behavior to change over the year, as the control constantly tries to maximize the economy of your system.

If you have a few end-customers that report the same “strange” behavior that can’t be explained and the behavior consist for a few days, then contact Fever Energy.

Production can increase because the system doesn’t just focus on you using as much of your own solar electricity as possible — but on maximizing your financial value.

For example, it may be more profitable to export electricity to the grid than to store it.

Your grid electricity usage may increase compared to the same month last year. This is because the system sometimes prioritizes selling your solar electricity to the grid (to maximize income) and instead buying cheaper electricity at night or during low-price hours.

This means you don’t always conserve your own electricity as much as possible, but in the end you earn more. The system is optimized — not to make you completely self-sufficient, but to give you the highest possible financial value by being an active part of the grid and the market.

If your battery often buys and sells electricity to/from the grid when Fever’s optimization is active, it’s because you make more money that way — perhaps through tax rebates, or through income when your battery helps balance the grid. Our optimization always ensures that the sum of your savings and your earnings is as large as possible.

Being self-sufficient isn’t always the most profitable way to use your battery. Self-sufficiency can reduce your costs, but it also means missing opportunities to earn money. Fever’s optimization constantly considers savings (e.g., using your own solar electricity) and income (such as tax rebates or payments for delivering flexibility to the grid), and every hour it chooses the option that gives you the greatest financial value.
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That’s why it can sometimes be more profitable to buy or sell electricity via the grid than to use your own production.

This behavior is completely expected. Sometimes it’s more profitable to sell solar electricity to the grid than to store it for later use. This may be due to low spot prices, tax deductions, or compensation from the grid company for supporting the grid. Fever’s optimization considers all these factors and always chooses the option that gives you the greatest financial value. When it’s more profitable to sell your solar electricity than to save it for later, that’s the result you will see.

No, not all. Some savings come from tax rebates that are paid out once a year and therefore don’t appear on the monthly invoice.

Yes, Fever takes demand tariffs into account. For residential systems, we automatically fetch the tariff information based on the grid area code — so you don’t need to do anything yourself. For commercial and industrial systems (C&I), you need to register your contract details with Fever so we can optimize based on the correct tariff.

Yes! We always stay updated on rules for both energy tax and VAT to ensure that costs and revenues are calculated correctly in our optimization.

When the tax rebate of SEK 0.60/kWh disappears at the end of 2025, it will naturally affect the system’s behavior. It will often be more profitable then to use your own solar electricity at home instead of exporting it.
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The system adapts daily based on market prices, tax rules, subsidies, and your household’s production and consumption patterns. In this way, it always ensures the best possible financial outcome for you — even when conditions change.

However, other tax incentives may replace the “60-öringen.” If so, we at Fever will make sure you can benefit from them if possible. We continuously follow and update our product according to regulations, tax incentives, grid costs, compensations, and market opportunities to ensure you always get the maximum out of your assets.

We always start from what maximizes the value in your home, and therefore our control adapts based on the electricity contract you have. The control may therefore differ if you have an hourly contract or a fixed-price contract, since we act based on what is best for you.

It is very rare for a Fever Espen device to malfunction. However, if you suspect that your device is not working properly, please follow the steps below:

Yes, Fever Espens are designed to be reusable.

Before installing a Fever Espen on a new inverter or at a new site, please follow the steps below:

Yes, Fever Espens are designed to be reusable.

Before installing a Fever Espen on a new inverter or at a new site, please follow the steps below: