The future of energy: home batteries, self-consumption, and smart grid management
Plug & play home batteries: surprisingly smart and simple
Contrary to the belief that home batteries are only for tech enthusiasts or aggressively marketed by sales-driven installers, the latest generation of home batteries—such as the Marstek Venus E—are designed for maximum simplicity. These devices can literally be plugged into a grounded socket, requiring no complex installations or significant renovations. This makes it easy for households to start with energy storage.
By utilizing energy storage, it’s possible to temporarily store surplus energy (e.g., during high solar and wind production) in a home battery. This energy can then be used during evening hours.
This not only directly reduces peak loads but also helps improve the balance of the power grid. Even relatively small batteries can make a significant difference in grid balance when managed intelligently. The straightforward installation also lowers the barrier for homeowners looking to reduce their energy bills and increase self-sufficiency.
However, the true potential of a home battery lies not in the physical device itself but in how and when you use it. Smart charging and discharging—based on solar power, dynamic energy tariffs, or grid load—make the difference between a wise investment and an expensive gadget. The purchase price of such a battery can quickly reach €1,900, which puts pressure on the payback period of the investment.
Using self-generated energy becomes the new standard for sustainable households
In a world where net metering is gradually being phased out (ending after 31-12-2026) and feed-in tariffs are under pressure, the concept of self-consumption is more relevant than ever. Simply put: the more of your own generated solar energy you use directly, the more profitable your solar panels are.
Imagine a family in Ede with a solar installation producing 3,500 kWh per year. Without a battery, they use only 30% of that energy themselves. The rest is fed back into the grid, for which they will soon receive only a fraction of the value. Additionally, in many cases, a feed-in fee must also be paid to the energy supplier. With a 5.12 kWh battery, self-consumption increases to 65%. This means that more than two-thirds of your solar power is used within your own home, for example, for your heat pump, charging station, or washing machine.
How Much Energy Does a Home Battery Really Provide? Understanding RTE and Available Capacity
A frequently asked question when purchasing a home battery is: how much energy can I actually get out of it? The Marstek Venus E (5.12 kWh) is a popular home battery due to its affordable price and simple installation. However, even with this battery, the full 5.12 kWh stated on the label is not entirely usable in practice.
Round Trip Efficiency (RTE)
The Round Trip Efficiency (RTE) indicates how much of the energy you put into the battery you can retrieve for use. For lithium iron phosphate (LiFePO4) batteries like the Marstek Venus E, the RTE typically ranges from 75% to 85%. For this calculation, we’ll use a realistic RTE of 76%, as often measured in practice with similar systems.
Available energy calculation
The Marstek Venus E has a rated capacity of 5.12 kWh, but the bottom 11% of the battery capacity is not used to protect the battery life. This means that 0.56 kWh is structurally unavailable:
Net usable capacity before losses:
5.12 kWh – 0.56 kWh = 4.56 kWh
If you then take into account the RTE of 76%, this is the energy that is actually usable if you fully charge and discharge the battery again. Since losses occur when charging and discharging, usable energy you can get from the battery will be half the losses or 88% will be available from the battery:
Effective energy available from the battery after RTE losses:
4.56 kWh × 0.88 = 4.01 kWh
What does this mean in practice?
So with a full charge cycle, you have 4.01 kWh of effective energy available to power your washing machine, dishwasher, lights or electric heater, for example. That’s enough to supply an average household with basic consumption for 8 to 10 hours, or to use your own solar power over the evening.
Financial benefit is just one side of the story. Self-consumption also contributes to a more stable grid. If everyone feeds back their surplus power at the same time—often midday during sunny weather—the grid becomes overloaded. If it’s also windy on that day, the surplus energy can be so high that it’s offered at negative prices under dynamic contracts. By storing this energy locally and using it later, you spread the load and contribute to the collective system. In the past, consumers with solar panels became energy producers. Now, these consumers are transitioning from energy producers to energy owners.
Behavior changes with insight; energy data acts as a mirror for consumers
A surprisingly powerful effect of a home battery is the behavioral change that follows from insight into your own energy consumption. Once you can see in real-time via an app or dashboard how much power you’re generating, consuming, or storing, the way you use appliances changes. Suddenly, you realize that when your washing machine runs during high energy availability, you don’t need to store that energy in your battery but can use it directly by doing the laundry.
We observe that households with access to their energy data consciously run the washing machine during solar peaks, charge their electric car when tariffs are low, and avoid unnecessary standby consumption. A small-scale study by an energy cooperative in Friesland showed that households with insight consumed on average 9% less grid power without sacrificing comfort. Additionally, our EnergyFlip users report behavioral changes leading to a quick 15% reduction in consumption over the entire period that energy monitoring took place.
This is because data literally opens your eyes. What was once an abstract energy contract becomes a dynamic game where you’re in control. You learn how your behavior affects costs, sustainability, and the energy network. Insight is therefore not a luxury but an essential link in the energy transition.
Energy trading with batteries: opportunities and pitfalls
One of the most discussed applications of home batteries is automatic trading on the energy market. In this scenario, an energy supplier or aggregator controls your battery at times when it’s beneficial for the grid—such as during imbalances between supply and demand—and shares (a portion of) the proceeds with you. Some home batteries, like the Marstek Venus E, even offer the option to select an AI mode. In AI mode, the charging and discharging of the home battery are autonomously determined based on available hourly energy market rates.
How does the AI mode of a home battery work?
The so-called AI mode of a smart home battery uses artificial intelligence to autonomously make decisions about charging and discharging the battery. It continuously monitors the hourly rates of the energy market. These data, for example, come from a dynamic energy contract, to determine when energy is cheap or expensive.
The AI mode combines dynamic electricity prices per hour for the next 24 hours. Based on this, the system creates a smart charging plan:
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Charging at low rates (e.g., at night or midday during an oversupply of wind or solar power).
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Discharging during peak hours when electricity is expensive, and grid demand is high.
This way, the battery can contribute to lower energy costs, optimize your self-consumption, and even, depending on the system, support the grid.
Example:
On Tuesday, electricity costs €0.12/kWh between 02:00 and 05:00 and €0.34/kWh between 18:00 and 21:00. The AI mode will then charge cheaply in the early morning and discharge in the evening to avoid expensive grid power. This way, you automatically save on your energy bill without manual intervention.
The reality is more unpredictable than it seems. In the summer of 2024, a household in Ede with a 20 kWh battery earned over €130 per month by trading on the imbalance market. In winter, this dropped to €45 due to lower market volatility and increasing competition from other batteries. In addition, Dutch grid operator TenneT recently tightened regulations to prevent overreaction from batteries, further reducing profit margins.
While some providers promise sky-high returns, energy trading with a home battery is much like investing: it comes with potential returns, but also risks. Especially when you purchase a battery yourself, you take on the majority of the risk. It can be lucrative, but only if you know what you’re doing and are prepared to accept the volatile nature of the market. If you’re considering participating in energy trading, factors such as feed-in tariffs and the end of net metering (after December 31, 2026) should weigh heavily in your decision.
A technical pitfall: phase imbalance
What many households don’t realize is that most Dutch homes have a three-phase power connection. Solar panels and batteries are often connected randomly to different phases. This may seem harmless, but it can have serious consequences.
For example, if you feed electricity back into the grid on phase 1, but your battery is charging on phase 2, you’re creating an imbalance in the grid. Instead of reducing the load, you’re shifting the problem elsewhere. Grid operators then face added complexity and sometimes even local outages.
That’s why it’s crucial that batteries — and inverters too — work in harmony with the phases. Smart controls, automatic phase detection, or neighborhood-wide coordination are essential and will become unavoidable in the future. Without these, we risk unintentionally worsening grid congestion — even if you think you’re helping with your home battery.
The collective answer to grid congestion is likely neighborhood energy storage
The real breakthrough won’t come from individual home batteries, but from a more collective approach. Imagine a neighborhood where each household has a 5 kWh battery. Instead of each device operating independently, an energy provider centrally controls all batteries based on grid load and energy tariffs.
A pilot in a suburb of Breda using a so-called “neighborhood battery” showed just how effective this can be: in a simulation with 80 households, solar power peaks were flattened by 55% and evening demand spikes were reduced by 90%. All without sacrificing comfort. Energy was generated and consumed locally.
This approach has a double benefit: households enjoy lower energy rates and a more stable grid connection, while the grid operator saves on costly infrastructure upgrades. Even households without solar panels benefit. A centrally controlled neighborhood battery — or smart, interconnected home batteries forming a “virtual power plant” — offers both economies of scale and systemic advantages.
Why the neighborhood battery isn’t a silver bullet (yet)
Though promising in theory, neighborhood batteries are currently not effective enough to solve grid congestion issues. Research from the Dutch province of Brabant points to several reasons:
1.Technical limitations
Standard neighborhood batteries (about the size of a shipping container) can’t store enough solar energy to handle summer overproduction. As a result, much of that power still floods the grid.
2. Lack of space in residential areas
These batteries take up a lot of physical space, making them hard to implement in most neighborhoods.
3. High costs
The investment required is too high. Without national government support, municipalities can’t afford them.
4. Unclear ownership
It’s often unclear who is responsible for managing these batteries. Grid operators aren’t required to do it, and if energy providers take it on, users may face double taxation or higher fees.
5. Better alternatives exist
In the long term, expanding and reinforcing the power grid is seen as a more effective and sustainable solution than neighborhood batteries.
What to consider when buying a home battery
Purchasing a home battery is more than an impulse buy — it’s a strategic decision. Depending on your goal (self-consumption, trading, or backup power), the required size, capacity, and features vary:
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For self-consumption, a good rule of thumb is 1 kWh of battery capacity per 1 kWp of solar panels. So, with 4 kWp of solar, a 4–5 kWh battery makes sense and will be effectively used.
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For trading, bigger is often better — but so is the risk.
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Smart software using real-time data is essential for optimal performance.
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Pay attention to which phase the battery is connected to and always register your battery via energieleveren.nl if you feed back more than 800W.
A dynamic energy contract is also essential to enable smart charging.
Conclusion: think strategically, not impulsively
A home battery is no silver bullet, but it can be a powerful tool. When used correctly, it brings benefits for both you and the power grid. For self-consumption, it’s a logical step — especially with the net metering scheme being phased out. For trading, it presents opportunities and uncertainties. And as a neighborhood-wide solution, it holds promise — though practical challenges remain.
Explanation of the impact matrix:
- Lower energy bill: High for self-consumption (5), medium for trading (3), low for backup power (1).
- Grid independence: Highest with backup (5) and self-consumption (4), lower with trading (2).
- Contribution to the energy transition: Highest with self-consumption (4), then trading (3), and backup (2).
- Protection against outages: Only truly relevant for backup systems (5).
- Potential financial return: Highest for trading (5), limited for self-consumption (2), almost none for backup (1).
- Peak load management: Best supported by self-consumption (3), followed by trading (2), and backup (1).
Don’t get carried away by flashy marketing. Know your goals. Do you want to use your own power, trade like a pro, or contribute to a local energy transition?