Example of Electricity Savings for a Retail Store

An example of electricity savings for a retail store is not assessed by how many panels fit on the roof. It is determined by operating hours, the loads running simultaneously, seasonality and, above all, how much of the generated energy is consumed at the time it is produced. For a business owner, these factors determine whether the photovoltaic system will simply reduce the electricity bill or become an investment that delivers meaningful control over energy costs.

Let us examine a realistic scenario for a small retail store in Greece. The figures are indicative, but the study follows exactly the same logic applied before selecting the equipment, system capacity and any potential energy storage.

Example of electricity savings for a retail store

We examine a 110 sq. m. clothing store, operating Monday to Saturday from 09:00 to 21:00. It has air conditioning, professional LED lighting, computers and cash registers, a security system, a small stockroom and a window display with continuous lighting during the afternoon and evening.

Annual consumption reaches 24,000 kWh. The highest demand occurs from May to September, when the air-conditioning units operate for many hours, and in December because of extended opening hours and lighting. With an indicative total charge of €0.22 per kWh, annual energy expenditure approaches €5,280, before accounting for tariff fluctuations, regulated charges and fixed fees.

The critical observation is that the store consumes significant energy during daylight hours. This is highly favourable for a photovoltaic investment because it reduces the need to purchase expensive electricity from the grid precisely when the system is generating power.

The proposed photovoltaic solution

For this particular consumption profile, an initial technical approach could include a 10 kWp photovoltaic system with a three-phase inverter and high-efficiency panels. On a suitable roof without significant shading and with the correct orientation, such a system could indicatively generate approximately 14,000 to 15,500 kWh per year, depending on the location, tilt, orientation, cable losses and operating temperature.

This does not mean that the store will eliminate its electricity bill. Generation does not perfectly coincide with consumption. On Sundays, public holidays or during periods of low commercial activity, part of the production may not be consumed on site. Similarly, after sunset, lighting, air conditioning and other loads are supplied by the grid or, where technically and economically appropriate, by an energy-storage system.

Based on the operating hours in this example, direct self-consumption of approximately 70% of annual photovoltaic generation could be achieved. In other words, of the 15,000 kWh generated, around 10,500 kWh are used by the store at the time of production. This energy creates the greatest and most immediate economic value because it does not have to be purchased from the electricity supplier.

What this means in euros

If the 10,500 kWh covered directly had an average final value of €0.22 per kWh, the annual saving from self-consumption would be approximately €2,310. The remaining generation is not automatically lost, as its economic utilisation depends on the applicable energy-settlement framework, the tariff and the connection terms. However, its value is usually not identical to the value of a kWh that avoids an electricity purchase during the store's operating hours.

In this example, an annual energy bill of approximately €5,280 could fall to around €2,700–€3,100, depending on the final charges and how the surplus generation is utilised. The reduction approaches 40% to 50% without a battery.

This figure is significant, but it must not be presented as a guarantee for every business. A store that operates mainly in the evening—for example, a bar or a food-service venue that opens late—has a different consumption curve. In such a case, the same photovoltaic capacity may deliver lower direct self-consumption unless combined with storage or load shifting.

When a battery increases the benefit

Let us add a LiFePO4 battery with approximately 10 to 15 kWh of usable capacity to the same store. The objective is not to supply the entire store throughout the night. It is to store part of the midday generation so that it can power loads after 18:00: lighting, the point-of-sale system, computers, security systems and part of the air-conditioning demand.

A battery can increase the direct utilisation of photovoltaic generation from 70% to 82%–88%, provided that it is sized correctly and there is stable afternoon demand. In our example, this means that 12,300 to 13,200 kWh per year are supplied by the system's generation instead of being purchased from the grid.

Using the same indicative energy price, the annual benefit could reach approximately €2,700–€2,900 solely from avoided electricity purchases. The total bill reduction could range from 50% to 60%, provided that the battery is used daily and does not remain underutilised.

This is also where the main trade-off lies: storage increases energy autonomy, enables better use of generation and can support critical loads during an outage when the design includes backup operation. At the same time, it increases the initial investment cost. It is not always the fastest payback option, but for businesses with high afternoon consumption or a need for uninterrupted operation, it may be the right choice.

Which data changes the final result?

Consumption in kWh is only the starting point. A sound technical plan examines at least 12 months of electricity bills, contracted capacity, peak demand periods, the type of electrical supply and the actual load curve. A store with refrigeration units, commercial ovens, heat pumps or electric-vehicle chargers has very different requirements from a store with basic lighting and two air-conditioning units.

Shading is equally decisive. Chimneys, neighbouring buildings, trees, antennas and parapets can reduce generation or require a different system architecture. In some cases, optimisers or an appropriate inverter are necessary. In others, a straightforward, high-quality string solution is technically adequate and more cost-effective.

Even small consumption-side interventions improve the outcome. Moving energy-intensive equipment operation to generation hours, correctly setting air-conditioning systems and replacing old equipment can increase self-consumption without enlarging the photovoltaic system. There is no value in oversizing an installation for energy that the store cannot use efficiently.

From an estimate to the right investment

The payback of a photovoltaic system for a retail store should not be calculated using a general rule. It is determined by the installation cost, available area, annual generation, energy price, self-consumption rate and potential battery integration. In a properly designed commercial application, the investment generally gains greater value as the business's daytime operation becomes more consistent.

Hellenic Energy approaches every project with a free technical study, assessment of actual consumption and selection of reliable equipment, so that each proposal is based on measurable data rather than promises. The objective is not simply to install a photovoltaic system, but to design a solution that reduces operating costs and supports the business's needs for years.

The next electricity bill can become the most useful tool for starting the study. With the right measurements, a retail store does not simply purchase equipment—it gains more predictable energy costs and greater control over its operation.