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Battery for business: cutting the power term and the penalties

SolarBox Team ·

At home, a battery mostly saves energy: you use at night what you generated by day. In a business the game is different —and often more profitable—, because an SME's bill isn't like a home's: a huge share of what you pay isn't the energy, it's the power. And that's exactly where a battery attacks what home-only self-consumption can't reach. That's why, in many businesses, a battery pays back faster than in a house.

A business bill isn't like a home bill

A normal home is on the 2.0TD tariff: two power terms and three energy periods. An SME, by contrast, is usually on 3.0TD (low voltage, contracted power above 15 kW) or 6.1TD (high voltage), and here everything multiplies: six power periods and six energy periods (P1 to P6), with very different prices by hour and month.

Two practical consequences you barely notice at home and that weigh a lot in a business:

  • The power term is expensive and fixed. You pay every day for the power you have contracted in each period, whether you use it or not. In many SMEs, the power term is a very large slice of the annual bill.
  • Exceeding your power is penalised. If at a given moment you exceed the contracted power of a period, excess power is billed (the heir of the old maxímetro). A single badly-placed peak —starting machinery, a compressor, an oven— can cost you all month.

What a battery does in an SME

A well-managed battery acts on the two things that weigh most —power and peaks—, not just energy. The levers:

  1. Shaving the peak to lower contracted power (peak shaving). If the battery covers the demand peaks, you can contract less power without falling short. Since the power term is fixed and expensive, lowering it by a few kW saves every day of the year.
  2. Avoiding excess penalties. The battery cuts the peaks before they exceed contracted power, sparing you the excess billing.
  3. Arbitraging across periods. Charge in the cheap hours (P6/valley) and discharge in the expensive ones (P1/peak): each cycle earns the price difference.
  4. Making better use of solar production. It shifts the PV surplus to the hours when the business actually consumes.
  5. Business continuity. With backup, a grid outage doesn't stop production or ruin a process mid-way —the lesson of 28 April is worth double when every hour of downtime has a cost.
  6. Participating in flexibility. As the demand-response market opens up (interruptibility, aggregators), an industrial battery can go from cutting costs to turning them into revenue (see self-sufficiency and the grid).

A business's peak: less contracted power, no penalties0 h6 h12 h18 h24 hPower demand (kW)Contracted powerpenalised excessWithout batteryWith battery (peak shaving)Illustrative working day. The battery shaves the peak: you can contract less power and avoid excess penalties.

The chart sums it up: the same activity, but with a battery the curve stays below the contracted power. That means two things at once —you can lower your contracted power (less fixed term every day) and you avoid the excesses of the peaks.

Why the return is usually better than at home

In an SME three things line up in your favour:

  • The power term and the excesses are large, and that's exactly what the battery attacks. In a home, the main saving is on energy; in a business, the power saving is added on top, and it's often bigger.
  • Daytime consumption matches the sun. Many businesses work by day, when PV produces: direct self-consumption is very high and the battery finishes off the peaks.
  • The tax treatment. Unlike a home (personal income-tax deduction), a company depreciates the investment on its books and can deduct it against corporate tax. We won't give specific figures because it depends on each case —your accountant will pin it down—, but it's a lever that doesn't exist at home.

We don't promise "3-year paybacks" blindly: it depends on your tariff, your consumption profile and whether you have sharp peaks. But when there are strong peaks, oversized contracted power or recurring excesses, the case for an industrial battery tends to be more solid than for a home.

How to tell if it's worth it

Three signs your business is a good candidate:

  • On the bill, the power term weighs as much as or more than the energy.
  • Excess power shows up some months.
  • You have short, sharp peaks (machinery, compressors, vehicle charging) on top of a flatter baseline.

If that sounds like you, it's worth looking at with your numbers. Ask us for a business analysis: we start from your real bills (power by period, excesses, load curve) and tell you which battery shaves the peaks, how much power you can drop and how long it takes to pay for itself.

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