A year ago, I made a deliberate decision. Not just to install solar panels or to add a home battery, but to fundamentally change how I interact with energy.

In earlier posts, I argued that energy is shifting from something static to something dynamic — something you don’t just consume, but actively manage. At the time, that was still largely a belief.

Now, one year in, I finally have something better than opinions:

real-world data.

And if I had to summarize that year in one sentence, it would be this:

The system works — but not in the way it’s often presented.

When It Works, It Really Works

Let’s start with what surprised me the most.

There are periods where my energy costs are not just lower, but actually negative. That’s not a theoretical scenario — it’s something that genuinely happens when dynamic pricing aligns with battery usage.

The system charges when prices are low or even negative, and discharges when prices increase. In those moments, your house effectively becomes a small energy trading node.

And when those market conditions line up, the results can be impressive. It’s one of the few situations where the promise of “smart energy” actually delivers in practice.

Scaling Up Changes the Game

Over the course of the year, I expanded my setup to roughly 20 kWh of storage capacity.

That shift turned out to be more significant than I initially expected. A smaller battery mainly helps you optimize your own consumption, smoothing peaks and reducing grid dependency. But once you reach a certain scale, the system starts behaving differently.

Instead of just shifting your own usage, you begin to interact with the market itself. The battery is no longer just a buffer — it becomes a tool that can capture price differences over time.

That’s where the real potential starts to emerge.

The Hidden Cost: Round-Trip Efficiency (RTE)

There is, however, an important technical detail that often gets overlooked: round-trip efficiency.

In my case, the system operates at roughly 88.33% RTE. That means that for every 1 kWh you store, you only get about 0.883 kWh back.

On paper, that sounds quite reasonable — and to be fair, it is. An efficiency of over 88% is actually a solid performance for a home battery system.

But the implication is important:

the missing ~11–12% isn’t absorbed by the system — it’s paid by you.

Every time energy is cycled through the battery, a portion is lost. And those losses accumulate over time, especially when the system actively charges and discharges based on market signals.

This doesn’t break the model, but it does mean that profitability depends heavily on having enough price spread to compensate for those losses. It’s not just about buying low and selling high — it’s about buying low, losing some along the way, and still selling high enough to come out ahead.

The Less Polished Reality

While the technical foundation is solid, the experience around it is not without friction.

Billing That Lacks Transparency

One of the biggest frustrations is the lack of clarity in the billing model. The invoice feels like a combination of multiple energy flows that are merged together without a clear separation.

It’s difficult to distinguish:

  • what your household actually consumed
  • what the battery did
  • what was traded with the grid

There are entries like “battery net earnings” that are counterbalanced elsewhere, making it hard to build an intuitive understanding of what is really happening.

For a system that is inherently data-driven, this lack of transparency is a missed opportunity.

Returns Are Lower Than Expected

Another important observation is that the financial returns are lower than often advertised.

Figures in the range of €1,200 to €1,700 per year for a 20 kWh battery sound attractive. In reality, the outcome is more modest.

That doesn’t mean the system underperforms — it means expectations are often set under ideal conditions. In practice, returns fluctuate based on market behavior, efficiency losses, and how the system is controlled.

Limited Control Over Your Own System

Perhaps the most fundamental limitation is control.

Despite owning the hardware, you don’t have full freedom over when the battery charges or discharges. The system operates within Zonneplan’s optimization logic, which may not always align with your own preferences or strategies.

If you’re someone who likes to experiment, optimize, or build your own logic, this can feel restrictive.

And Then There’s the Future: Life After Net Metering

Looking ahead, one thing is clear: the Dutch energy landscape is going to change significantly.

The gradual removal of the salderingsregeling (net metering) will fundamentally alter how solar energy is valued. Today, excess solar production can still be offset against your consumption, effectively allowing you to use the grid as a free battery.

That model is disappearing.

And when it does, two things will happen at the same time:

  • you will be compensated less (or not at all) for energy fed back into the grid
  • you will pay full price — including taxes — for the energy you consume

This shifts the economics in a very direct way.

What That Means in Practice

In my current setup, with solar panels and a home battery, I ended the year with roughly:

–€650 in net energy costs

That’s not a projection — that’s actual data.

When we model the same setup without net metering, the picture changes:

–€480

So yes — the result becomes less favorable.

And there are clear reasons for that:

  • exported energy is no longer offset 1:1 against consumption
  • taxes and grid fees apply more directly to consumed energy
  • inefficiencies (like RTE losses) become more visible in your total cost

But here’s the key point:

even without net metering, the system still performs strongly.

The Real Comparison People Miss

Most discussions focus on the drop from –€650 to –€480 and conclude:

“See, it’s getting worse.”

That’s technically true — but it’s also the wrong comparison.

Because the real baseline is not “with vs without saldering”.

The real baseline is:

with vs without solar and a battery

And that changes everything.

Without solar panels and without a home battery, a typical household would easily end up with:

€500 – €750 in annual energy costs

Depending on usage and market conditions.

So even in a future without net metering, the comparison becomes:

  • –€480 with solar + battery
  • +€500 to +€750 without

That’s a structural difference of roughly:

€1,000+ per year

Why This Matters

The removal of net metering doesn’t break the case for solar and batteries — it actually clarifies it.

It forces the system to behave more like it was always intended:

  • consume your own energy
  • store what you can’t use immediately
  • minimize reliance on the grid

And in that model, a home battery is no longer an optimization.

It becomes essential infrastructure.

The Catch

There is, however, a condition.

As net metering disappears, three things become more important:

  • efficiency (your RTE losses directly impact your costs)
  • control (when do you store vs. when do you use?)
  • transparency (what is actually happening in your system?)

And this is exactly where current solutions — including Zonneplan — still have room to improve.

What This Year Really Taught Me

After a full year, my perspective is both more positive and more realistic.

The system does deliver value. It reduces costs, increases flexibility, and makes better use of locally generated energy. In certain conditions, it even creates profit.

But it’s not a passive investment, and it’s certainly not a guaranteed return machine.

It’s a system that operates in a complex, dynamic environment — and your results will reflect that complexity.

Final Thought

Would I do it again?

Yes.

But not because it’s perfect.

I would do it because it represents a shift toward a more resilient and decentralized energy system — one where you are no longer just a consumer, but an active participant.

And if the first year was about understanding how the system behaves…

the second year will be about gaining more control over it.