The combination of solar panels + smart charging + battery is often presented as the holy trinity of sustainable mobility. In practice, it is not always profitable. Here is when it is, and when it is not.

The energy flow

Solar panels produce energy during the day, especially when cars are not plugged into the charging station. A battery buffers that energy and releases it in the evening when cars return. Dynamic load balancing ensures that the charging capacity follows solar production and grid load.

When is it profitable?

  1. Business sites with an existing PV installation — the added value here is primarily the battery addition, with a payback period of 5–8 years.
  2. Fleets with predominantly overnight charging — the battery buffers daytime production for evening hours.
  3. Sites with capacity tariffs and high peak power demands — peak shaving via battery reduces annual grid costs by €2,000–€8,000.
  4. Companies with dynamic energy price contracts — charging during negative hourly rates, discharging the battery during peak prices.

When is it not profitable?

  • Business sites without PV — the battery investment is too high without a free energy source.
  • Fleets with predominantly daytime charging — cars are not present during the day, so PV energy is not used directly.
  • Small fleets (<5 EVs) — the scale effect is missing, and the payback period exceeds 10 years.

Concrete calculation example: SME with 12 EVs and 50 kWp PV

  • Investment in 100 kWh battery + dynamic load balancing: €70,000
  • Annual savings: €4,500 (peak shaving) + €3,500 (PV self-consumption) = €8,000
  • Payback period: 8.5 years with stable energy prices, faster if prices rise.

Conclusion

Calculate it based on your actual consumption profile. An installer who sells you this without knowing that profile is selling you a gamble.

Read also

Would you like to have your own scenario calculated? Schedule a consultation — we combine your grid connection, PV production, and charging profile into one concrete calculation model.