Storage on Your ATR: Why a Solar Project With Batteries Is Worth More

A few years ago, a solar project in Romania was valued almost entirely on how many megawatt-hours it could produce. Today that is no longer enough. The question investors ask me now is different: at what hours will those megawatt-hours be sold, and at what price?

The reason is simple. Romania, like most of Europe, has built a lot of solar capacity, and it all produces at the same time. Around midday, on sunny days, the market is flooded with energy and prices drop sharply, sometimes to zero or even below. In the evening, when the sun goes down and demand rises, prices climb again. A standalone solar plant sells most of its energy in the cheapest hours of the day. That is the problem storage solves.

A BESS (Battery Energy Storage System) placed next to a solar plant absorbs part of the midday production and releases it in the evening, when the same energy is worth much more. The plant does not produce a single extra kilowatt-hour, yet it earns more, because it sells at better hours. On top of that, a battery can take part in balancing services for Transelectrica (the Romanian transmission system operator), which pays for flexibility, and it reduces the energy lost when the grid limits the plant's output.

What makes hybridization especially interesting in Romania is the grid connection. Securing a new ATR (Aviz Tehnic de Racordare, the technical grid connection permit) has become one of the slowest and most uncertain steps in development. A project that already holds one owns something the market values highly. Adding storage behind the same connection point uses that capacity much better, instead of competing for a new one. In most cases the ATR has to be updated to include the battery, but that is a very different exercise from starting a connection from zero.

There is also a sizing question that investors often overlook. Many solar plants are built with more panel capacity than their grid connection allows, so on the sunniest hours part of the production is simply cut off. A well-sized battery captures exactly that energy, which would otherwise be lost, and moves it to the evening. In those projects, storage does not only shift value, it recovers it.

Of course, a battery is not a magic button. It adds CAPEX (capital expenditure), it needs a clear strategy for how it will be operated and traded, and its value depends on market rules that keep evolving. The duration matters too: a two-hour battery and a four-hour battery play different roles, and the right choice depends on the project and the investor's goals. These are exactly the points that should be in the financial model, not left for later.

At BRES ENERGY we look at every solar project on our platform with this question in mind: what would it be worth with storage? Where it makes sense, the BESS is already part of the project we present, sized and modelled, so the investor sees the full picture from the start. Several of our solar projects are offered today as hybrids for exactly this reason.

The next phase of the Romanian market will not reward the projects that produce the most. It will reward the ones that sell at the right time. A grid connection with storage behind it is no longer an upgrade. More and more, it is the standard.