Virtual Battery: Buying Power at €0.08, Selling at €0.15

Virtual Battery: Buying Power at €0.08, Selling at €0.15

The virtual electric battery does not exist. There is no giant cloud bank storing the kilowatts you feed into the grid. What exists is a credit system: your supplier pays you for surplus energy and deducts it later when you consume. The issue is the price differential. According to calculations circulating in online debates, you are paid 8 cents while being charged 15. This margin, which varies by supplier, time, and location, constitutes the business model. It explains why the virtual battery, as marketed, remains an illusion.

The Differential Trap

The mechanism is simple. You export energy when your solar panels produce more than you use. The supplier credits this on your bill, but at a lower rate than what they charge you when you draw from the grid. "You get 8 cents back, but pay 15 cents when you take from the network," summarizes the initial argument. This gap is not a system error; it is its essence. Utility companies will never give you the kWh you exported; they provide less money than they charge you to cover non-generation periods.

The situation worsens in winter. In December and January, photovoltaic production plummets. A user with heat pumps and eighteen 550W panels reports producing around 400 kWh in December, of which about 100 are self-consumed and the rest goes to the grid. Their winter consumption ranges between 700-1000 kWh monthly. The summer credit balance runs out, and thereafter everything is paid at grid prices. The full calculation, accounting for deficit and surplus months, reveals a surprising difference.

The Illusion of Independence

Some argue that physical batteries are the solution. One user claims to have a 15 kW battery and suggests charging it during off-peak night hours to discharge during the day, leveraging EV tariffs. "We need to run the numbers because I am not entirely sure this is amortizable given battery costs," they admit. The idea is attractive but clashes with reality: batteries remain expensive and limited in their temporal utility.

Another user breaks down their case: an installation costing €8,200, subsidized up to €4,500, with €1,500 saved in property tax over five years and €1,200 in tax deductions. Total cost: €1,800. "So far, I have paid €0 for electricity since installing it," they say. But their case is exceptional: they have over €400 accumulated in the virtual battery and face winter deficits. Profitability depends on consumption, location, and generation.

The Role of Subsidies

Aid distorts the market. "The flood of subsidies injected across all sector layers completely skews the numbers," it is argued. Major suppliers also want their share. If something relies on aid and regulation, it is doomed. The criticism is clear: if the technology were truly profitable, subsidies should end, letting supply and demand regulate.

The problem is that without aid, the math doesn't work. Physical batteries are costly, and virtual ones depend on a differential that always favors the supplier. Furthermore, the trend is to pay less for surplus. "Installing panels for self-consumption makes sense; installing them solely to generate surplus is nonsense," one user concludes.

The Future: Penalizing Exports

Things could get worse. "They will eventually financially penalize feeding into the grid due to lack of storage capacity," predicts a user. More production during peak solar hours is no longer needed, but rather at other times. Solar energy is abundant and cheap during midday but scarce when there is no sun. This drives surplus prices down and increases nighttime consumption costs.

Technical solutions exist: large-scale storage like compressed air or solid-state batteries. However, this does not solve the individual's problem. If home batteries become widespread, the State loses tax revenue. "You will pay for private storage because they won't allow renouncing tens of thousands of euros in taxes," warns a user. The inevitable question arises: if technology advances to enable self-sufficiency, how will the system continue to collect fees?