Why are batteries discharging at night?

Answer

The optimiser is making real-time decisions to get the best financial outcome based on their tariff, battery level, and expected solar generation. This behaviour is expected. Optimisation is always weighing up multiple factors to make cost-effective decisions throughout the day and night - and discharging overnight is often part of that.

Details

Optimisation is programmed to respond to the most cost-effective energy strategy. If the tariff structure has low import rates at night or high export rates, optimisation may choose to:

• Discharge and export energy when the export rate is high, maximising earnings. If the export rate is particularly high at night, optimisation may take advantage of these favourable rates. This happens especially when the cost of importing electricity is lower than the export rate, allowing your system to profit from the difference.

• Discharge and export energy when the import rate is high, arbitraging the battery to generate overnight revenue.

• Use stored energy to power the home instead of grid electricity. If the cost of importing electricity is higher than using the stored energy in your battery. This ensures you get the best possible return based on your tariff plan.

Preparing for Tomorrow's Solar Generation

If optimisation forecasts that a large amount of solar energy will be generated the next day and an advantageous export rate, it may proactively discharge some of the stored energy at night. This makes space for new solar energy so that none of it is wasted when your panels start producing in the morning.

Why don't batteries fully charge? 

Answer

Optimisation is designed to save you money and maximise efficiency, so if your battery didn’t fully charge, it was likely the best financial decision based on tariffs, solar forecasts, and energy usage. 

Details

The three main reasons a battery hasn't fully charged are:

Expected home usage

Optimisation analyses customers' typical energy consumption and optimises battery charging accordingly. If it predicts that a consumer won't need a full battery to cover their usual energy needs, it won’t charge to 100% (or their set limit) unnecessarily. This helps prevent wasted energy cycles and reduces costs.

Preparing for Solar Generation

If a high amount of solar generation is expected the next day, the system may leave space in the battery to store that free solar energy instead of filling it up with grid electricity. This ensures that customers make the most of their self-generated power rather than relying on grid imports.

Avoiding unnecessary charging costs

Charging to 100% (or the set maximum charge limit) when it's not needed can sometimes increase costs or lead to unnecessary cycling. 

Why do batteries charge when they are not empty?

Answer 

If customers notice that their battery started charging even though it wasn’t empty, don’t worry, this is a normal part of how optimisation works. Optimisation is making smart decisions to maximise savings and efficiency based on several factors, including tariff, usage, generation and protecting battery health. 

Details

Here’s why it might have charged before reaching 0%:

Taking advantage of low tariff prices

If optimisation detected a cheap energy price window, it may have charged early to ensure customers get the lowest-cost electricity instead of waiting until the battery was empty and potentially needing to charge at a higher rate later.

Preparing for high energy demand

If the system anticipates that your home will need a lot of energy soon, it may charge the battery in advance to avoid reliance on expensive grid electricity when demand spikes.

Managing solar generation

If tomorrow’s solar forecast is low, optimisation may choose to charge ahead of time so your home has enough stored energy to last through the day.

Protecting battery health

Device manufacturers often recommend a minimum charge level a battery should reach as part of normal operations. This is usually around 5-10% of capacity. 

Why does optimisation history say charging from “grid/solar” overnight?

Answer 

The label “grid/solar” reflects the optimisation mode applied, which allows the battery to charge from either source when beneficial. However, during overnight hours, solar isn’t available, so any charging that takes place is from the grid. "Grid/solar" mode means the system is permitted to charge from either source, not necessarily both at the same time.

Charge from solar mode can also be used to store the current charge in the battery in anticipation of the import tariff changing to an expensive period.

Overnight, if a consumer sees battery charging activity under this label, it is grid charging - optimisation is likely taking advantage of low overnight import rates.

How does optimisation affect warranties?

Answer

If a consumer has concerns about how optimisation may affect their battery warranty, it's best to review the specific warranty terms provided by the manufacturer.

Ultimately, optimisation is designed to help customers get meaningful financial return from their battery system, while operating safely within expected limits.

Details

Battery optimisation is designed to help customers get more value from their energy systems, but some may wonder whether frequent charging and discharging could impact their manufacturer's warranty. It’s important to understand how each manufacturer defines and enforces their terms.

Battery cycling and how it’s counted

Most battery warranties include limits based on charge/discharge cycles, depth of discharge, or total throughput (e.g. number of kilowatt-hours moved over the battery’s lifetime). However, different manufacturers define a “cycle” in different ways. For example:

One manufacturer may count a full 100% charge and discharge as one cycle. Others may combine smaller partial charges/discharges that add up to 100% into a single cycle.

As a result, one battery may appear to cycle more quickly than another, even under similar usage patterns.

Third-Party Control and API Use

Some warranties also include clauses about third-party control, especially when an optimiser uses an API to control the battery. While most systems allow third-party integration, there may be conditions or restrictions in the warranty. Consumers are advised to:

• Review the manufacturer’s warranty documentation

• Check whether API-based control or third-party optimisation is explicitly allowed or restricted

Optimisation is designed to stay within safe limits.

The optimisation engine is built to work within the battery's defined parameters, such as:

• Minimum and maximum charge levels

• Charge/discharge rate limits

• Daily throughput or usage boundaries

• It does not aim to overuse the battery—it aims to strike a balance between system health and financial value, based on tariffs, solar forecasts, and energy demand

Can customers take advantage of GivEnergys GivBack events?

Answer

While it is possible for customers to participate in GivEnergy’s GivBack events, doing so while using optimisation is not recommended. This is because both systems attempt to control your battery, and running them simultaneously could lead to conflicting commands and suboptimal financial outcomes.

Details

Optimisation continuously makes decisions based on tariff rates, solar forecasts, and expected home usage to ensure you get the best financial outcome. However, GivBack events involve demand-side response (DSR) mechanisms, which also attempt to control the battery. If both systems are active at the same time, they could interfere with each other, leading to unexpected behaviour or reduced financial benefits.

Is there a way to do both?

If customers turn off optimisation at the right time on the day of a GivBack event and then turn it back on afterwards, they will be able to participate. However, this comes with risks:

• Disrupting the Optimisation Strategy – The optimisation engine expects to control the battery throughout the day.

• Disabling it temporarily could interrupt its planned charging and discharging cycles.

• Potential Financial Losses – Since optimisation is designed to maximise savings across the full day, turning it off for a GivBack event could result in higher overall costs.

Can consumers take advantage of Octopus Power-Ups events?

Answer

Optimisation doesn’t take Power-Ups into account. This is because there is no way for the optimisation engine to know that the event is taking place. 

Details

Power-Ups require manual opt-In

Unlike standard tariff rates, Power-Ups are not automatically applied—consumers need to manually opt in each time a Power-Up is available. Because this is a user action and not a system-wide change, our optimisation engine cannot detect whether users have opted in or not.

Tariff rate remains unchanged

Even during a Power-Up, consumers' usual tariff rate doesn’t change, they are still charged as normal and then credited back later by Octopus Energy. Since optimisation works based on real-time tariff pricing, it has no way of knowing that energy used during the Power-Up period will effectively be free.

No API or Data Feed for Power-Ups

At present, Octopus Energy does not provide Power-Ups via tariff data or any other API. This means that there is no automated way for our system to recognise when a Power-Up is happening or if a user has opted in.

Can consumers still make the most of Power-Ups?

There is no downside to opting in to a Power-Up, but optimisation wont necessarily maximise the value of that free hour of electricity. Usage chart data will incorrect for that hour as they'll show a cost for the energy rather than free.

Why don't batteries use their full range?

Answer

If a consumer notices that their battery rarely charges to 100% or discharges all the way to 0%, it can feel like they’re not getting the most out of their system. However, there are good reasons for this behaviour—most of them tied to battery health, cost optimisation, and real-world constraints.

Details

Battery Protection Limits

Most batteries don’t actually allow full use of 100% of their capacity. Manufacturers often reserve a buffer at the top and bottom of the battery’s range to protect long-term health.

For example, a “10kWh” battery might only give access to 8–9kWh in practice. This is by design, to extend lifespan and avoid deep discharges or overcharging, which can degrade the battery over time.

Safety margins and settings

In some setups, consumers (or installers) may have set custom charge limits in their inverter or battery app. These settings can cap the minimum or maximum charge to leave room for:

• Grid backup power

• Warranty protection

• System constraints (like G100 export limits)

Efficiency losses and real-world conditions

Charging and discharging are not perfectly efficient. The battery may appear to stop short of its maximum or minimum due to:

• Heat management

• System losses

• Slight delays or inverter thresholds

If a consumer feels their battery is consistently underperforming, it's worth checking:

• Their system settings (inverter/battery app)

• Their optimisation preferences

• Whether their tariff or usage profile is limiting the battery’s opportunities to charge or discharge fully 

Optimisation doesn’t aim for full capacity

Optimisation makes decisions based on your tariff, forecasted solar generation, and expected home usage. If it doesn’t make financial sense to fully charge or discharge the battery, optimisation won’t force it.

It might partially charge overnight to take advantage of low-cost import, but stop short of full if solar is expected in the morning. Similarly, it may leave some charge in reserve if high export or usage is forecasted later in the day. 

What happens if I turn optimisation off and on every night?

Answer

While it's possible to turn optimisation off and on as often as you'd like, we don’t recommend switching it daily.

Details

Optimisation plans your battery’s behaviour using data like your tariff, forecasted weather, and battery usage, and it works best when it has a clear, uninterrupted window to operate. In fact, it plans charging and discharging up to 24 hours in advance.

• Charge at the cheapest, most efficient times

• Prepare for sunny days by making space for solar

• Respond to tariff price changes automatically

When optimisation is off, your battery defaults to Balance mode, which doesn't maximise earnings or savings.

For the best results, we recommend leaving optimisation on continuously unless you have a specific reason to pause it.

Why do batteries charge and discharge on repeat? (arbitrage explained)

Answer

If a consumer notices their battery charging and discharging multiple times in a day, it may seem unusual, but it's often a sign of smart optimisation at work. This pattern is known as arbitrage, and it's a common strategy to help consumers reduce energy costs or even earn from their energy system.

Details

What Is Arbitrage?

Arbitrage refers to the practice of charging the battery when electricity is cheap and discharging it when electricity is more expensive. Optimisation uses this method to minimise grid import costs and, in some cases, maximise export value.

Why Might This Happen?

A battery may charge and discharge repeatedly throughout the day, or more commonly, overnight. This is especially likely when the export tariff rate is higher than the import tariff rate, and optimisation sees windows of opportunity to save or earn money.

Overnight is typically when these opportunities occur, particularly on dynamic tariff, where prices fluctuate significantly. For example, the system may charge the battery during a very low-cost period, then discharge when export rates or home usage value is higher—even if that’s only an hour or two apart.