How much does a power outage really cost your business?
Deferred sales, margin, stock and restart: estimate an outage's cost to compare backup solutions for your business in Tunisia.
The cost of an outage depends on the margin actually lost, affected products and additional expenses. Simply multiplying outage hours by usual revenue gives an initial figure for sales at risk; it does not yet calculate the economic loss.
A backup system is therefore planned around two questions: which services can it maintain, and what is their value to your business? The aim is to compare solutions using data that supports your decision.
Key points: a postponed sale is not necessarily lost; revenue and margin are different; backup equipment has its own purchase and operating costs.
1. Reconstruct the consequences of an incident
Record the date, time slot, outage duration and time needed to resume operations. Identify abandoned and postponed orders, spoiled products and expenses triggered by the incident.
A quiet-period outage does not have the same impact as an interruption during evening service. A refrigeration failure after closing can also cause a loss without interrupting sales at that moment. Your business history helps build several scenarios instead of an unrepresentative average.
2. Move from sales at risk to lost margin
Variable costs are expenses that change with sales, unlike fixed costs already incurred. This distinction is used in break-even and contribution-margin methods. Methodological source: Small Business Administration.
Here is a wholly fictional case, not a benchmark for Tunisian businesses:
| Step | Assumption and calculation |
|---|---|
| Normally expected sales | 400 DT/h for 2 h = 800 DT. |
| Share of sales eventually postponed | 25 %, or 200 DT. |
| Permanently lost revenue | 800 − 200 = 600 DT. |
| Variable costs avoided on those sales | 45 % × 600 = 270 DT. |
| Lost contribution margin | 600 − 270 = 330 DT. |
| Spoiled stock, valued at cost | 80 DT. |
| Additional restart costs | 60 DT. |
| Estimated economic loss from the incident | 330 + 80 + 60 = 470 DT. |
The 80 DT represents the cost of products separate from orders already included in lost margin. The 60 DT represents actual additional expenses in this scenario. A fixed cost already included in operations must not be added again without justification.
3. Estimate what backup can protect
Assume a solution preserves 80 % of the margin at risk, avoids 60 DT of stock loss and 40 DT of restart costs. The protected value would then be 264 + 60 + 40 = 364 DT for this incident. With 20 DT of variable backup costs, the operating benefit for the event would be 344 DT.
This estimate depends on the services actually maintained. Power that protects refrigeration and the till does not automatically preserve sales requiring an oven or an unprotected machine. Available duration and any transfer delays also affect the result.
Specify “power continuity assessment”, your critical equipment and a few observed outages. The team contacts you using your name, phone number and email; the assessment is free and without obligation.
4. Test several frequencies without inventing a forecast
The future number of incidents remains uncertain. In the previous example, several assumptions can be tested:
| Hypothetical annual scenario | Benefit from events at 344 DT each |
|---|---|
| 2 events | 688 DT/year. |
| 6 events | 2 064 DT/year. |
| 12 events | 4 128 DT/year. |
These frequencies support sensitivity analysis; they do not describe national conditions or your business. The solution’s fixed costs must then be deducted: maintenance, any insurance, monitoring and component replacement. Initial investment and financing are assessed separately.
5. Separate solar benefits from backup benefits
An installation can reduce electricity purchases during normal operation and maintain part of the business during an outage. Both benefits can be included in an assessment if they use distinct periods and cash flows.
During an outage, the same energy must not be counted both as avoided grid purchases and as an additional saving already included in backup costs. The battery also needs recharging; that energy and conversion losses have a cost.
The twenty-year business example presents the cash flows of a solar PV investment. For backup storage, continuity and the value of preserved services are added according to project characteristics.
6. Build a decision-making file
The quotation must describe powered equipment, target durations, recharging conditions, power limits and maintenance services. Financing adds the deposit, instalments, fees and guarantees. The assessment then compares the full budget across several operating scenarios.
For a Tunisian business, connection conditions and equipment selection are checked against the applicable technical framework, including the STEG reference of July 2026. Provisions announced for residential storage do not automatically apply to business premises.
Explore the café or tea room case, refrigeration priorities and backup technology comparison. Our business page also covers daytime consumption assessment.
— Your bills and outage history will replace this example with your business data. All topics are available in our solar PV advice.