Solar is about more than savings
What changes when a business generates part of its own electricity? Beyond the value of the kilowatt-hours produced, its exposure to future purchasing prices changes. Two illustrative calculations show how to assess that effect and when battery storage needs a separate analysis.
Lower grid purchases, lower price exposure
A business buying all its electricity from the grid is exposed to its supply contract and to price changes when renewing that contract. Under variable-price contracts, market movements can also affect costs during the contract term.
Solar reduces purchases during hours when generation covers demand. This reduces exposure for that quantity of electricity. Remaining demand still depends on grid purchases, and the project has its own investment and maintenance costs. Its value should also be tested against lower grid-electricity prices.
Annual business consumption: 500,000 kWh
Solar electricity directly consumed on site: 150,000 kWh
Remaining grid purchases: 350,000 kWh
On-site generation covers 30% of annual consumption in this simplified example. That does not mean the total bill falls by 30%. The financial effect depends on contracted prices, timing, network charges and other costs.
Why does the timing of demand matter?
Two businesses with identical annual demand may have different opportunities to use solar electricity. A facility operating during sunny hours may use more output directly; evening operation and non-working weekends can produce more surplus.
Assess generation and demand over sufficiently short intervals. Annual generation equalling annual consumption does not, by itself, establish energy independence.
Where can a battery add value?
A battery can store part of the surplus for later use. Depending on the project, it may also help manage peak demand. The European Commission identifies energy storage as an important source of flexibility for the energy system.
A battery requires its own business case: power, usable energy capacity, cycles, losses, ageing, cost and control strategy. The same capacity does not deliver the same result at every site. Backup during a grid outage requires an appropriate design and is not an automatic consequence of installing a battery.
What should you analyse before deciding?
First match the consumption profile with generation potential. Then compare the project with and without storage, using realistic assumptions for prices, financing and future operating changes.
This establishes how much demand the business can cover itself, how much it still needs to purchase and what value it receives for the total investment.
What does 30% on-site electricity mean in euros?
Using the example of 150,000 kWh of directly consumed solar electricity, assume the comparable grid-electricity price rises by €0.05/kWh across all hours under consideration.
| Scenario | Grid purchases | Additional energy cost |
|---|---|---|
| No on-site generation | 500,000 kWh | €25,000 |
| 150,000 kWh of directly consumed solar | 350,000 kWh | €17,500 |
| Difference | 150,000 kWh | €7,500 |
The €7,500 represents lower exposure in this scenario. It must not be counted again as an additional benefit on top of the value of the same solar electricity. Price changes are already part of that valuation. A fixed-price contract may not change immediately when the market moves; hourly pricing requires an hourly calculation.
On-site generation and continuity of supply are different objectives
Solar can reduce purchases while the grid is operating. This does not automatically keep production running during an outage. Backup requires identifying critical loads and designing suitable isolation, conversion and storage systems in line with the operator's conditions. Specify separately whether the goal is lower cost, peak-demand management or continuity during outages.
How can you avoid overvaluing a battery?
Storage shifts energy through time, with losses. The US Department of Energy explains how energy can be stored when available and used later. DOE: solar and storage basics.
Assume 100 kWh of surplus enters a battery. At an assumed 90% round-trip efficiency, 90 kWh is available later. If avoided purchases are worth €0.15/kWh and immediate export could earn €0.05/kWh, the difference is:
Battery costs, ageing and other relevant costs still have to be covered. Both prices and the efficiency are illustrative assumptions, not a quotation, market data or specifications for a particular battery.
Do not automatically assume 365 such cycles a year. The available cycles depend on actual surplus, demand and operating limits. If the battery also manages peaks, the model must verify sufficient energy and power at those times.
Three questions for your next energy plan
- How much electricity do we use while solar is generating, and what do we still need to buy at night and in winter?
- How does the outcome change with lower grid prices or different shifts?
- What additional value does storage deliver compared with the same project without a battery, after all costs?
Your first step: collect your supply contract and consumption profile alongside your bills. Identify electricity quantities, the pricing mechanism and backup requirements separately. They inform different parts of the solution.
Based on EMISSIO TRADE's LinkedIn post of 15 September 2026. Further references: European Commission: energy storage; HEP ODS: connecting solar and battery storage, including island-operation conditions (Croatian). Illustrative calculations do not forecast a specific project's results. Content reviewed on 15 September 2026.