Physical battery or virtual storage: two different models.

The word “storage” describes two different arrangements here. A physical battery stores energy on site. A virtual-storage offer contractually accounts for electricity exported and electricity consumed later. ADEME explains this distinction for the French market; it should be the starting point for any comparison.

Compare the complete service

Do not compare only a battery purchase price with an advertised virtual-storage subscription. Build a full annual bill for each option: electricity purchases, fixed fees, variable charges, export value and equipment cost. Use the same generation and consumption baseline.

Separate confirmed information from unanswered questions. An advertising figure should not fill a missing contract term. If unused credit is not clearly addressed, request a written answer before treating it as a certain saving.

Terms to examine

• How are future consumption entitlements calculated?
• Are there caps, expiry dates or seasonal limits?
• Which charges remain payable when credit is used?
• What happens to accumulated credit if you cancel or move?
• Does joining require a different supplier or affect another agreement?

These are review questions, not a claim that every product has identical terms. The answers must come from the contract offered for your installation. Offers outside France may use similar names for different arrangements.

Make a personal comparison table

Create three columns: current arrangement, physical battery and virtual-storage offer. Record initial cost, expected annual expenditure and unpriced elements in each. Add rows for leaving the contract and for replacement or maintenance. This exposes differences that a single per-kWh headline can hide.

For hardware, obtain confirmation of usable capacity and functions. For the service, confirm credit rules and the full supply cost. Do not assign a backup-power function to an electricity-accounting arrangement.

Choose around your actual objective

Are you trying to reduce your bill, keep energy locally or prepare a backup system? Those goals do not automatically lead to the same answer. Our suggested approach is to define the need first, then compare options across a complete year.

Keep dated copies of the contract and calculation. They provide a baseline for checking the eventual outcome. If a supplier later changes its offer, record the new conditions separately instead of silently replacing the assumptions behind the original decision. That makes an annual review much more useful.