Design and Operation of Solar Plus Storage Projects: What Operators Need To Be Aware Of

Key Takeaways

• Adding BESS to solar assets creates flexibility, but it also changes the operational playbook.  

• Solar experience is useful, but BESS requires additional knowledge around energy capacity, degradation, state of charge (SOC), state of health (SOH), cycling, and warranty risk.  

• Hybrid assets should be designed for future operating scenarios, not only day-one constraints.  

• EMS selection should be a strategic decision, because it plays a critical role in control, safety, and performance.  

• More data does not automatically mean better insight, especially when key values are estimates rather than sensor readings.  

• Hidden issues — imbalances, SOC errors, cooling faults, recoverable energy losses — can quietly reduce revenue; independent BESS analytics surfaces them, so operators can improve performance and reduce penalty risk.

‍

Why BESS Changes Solar Operations

Adding battery energy storage to solar assets can unlock new revenue opportunities and make renewable energy more flexible. But hybridization is not just a matter of adding a battery next to an existing PV plant.

Solar and BESS are fundamentally different assets to operate. Solar is relatively predictable. When the sun shines, the asset produces energy, subject to grid constraints, market prices, and technical availability. A battery, on the other hand, needs constant decisions: when to charge, when to discharge, how much energy to hold back, which markets to serve, and how to protect long-term asset health.

That shift changes the way asset owners, IPPs, and operators need to think about design, operations, data, and risk.

‍

Solar Experience Is Valuable, But Not Enough

Many teams entering BESS already know how to manage renewable assets. That experience is valuable, but BESS introduces new technical and operational variables that solar tools and workflows do not fully cover.

BESS adds a new technical layer.

With solar, power is often the central planning factor. With BESS, energy becomes just as important. Energy capacity influences cost, footprint, runtime, revenue potential, and long-term value. The relationship between power and energy also shapes how long the system can discharge and which revenue streams it can realistically serve.  

BESS operators also need to work with KPIs that do not play the same role in solar operations, including:

• State of charge  

• State of health  

• Depth of discharge  

• Equivalent full cycles  

• Imbalances  

• Auxiliary consumption  

These metrics directly affect performance, warranty compliance, safety, asset lifetime, and revenue.

‍

Hybrid Projects Need Future-Ready Design

A hybrid asset should not only be designed for the operating model it has on day one. It should also account for how markets, grid rules, permits, and revenue strategies may change over time.

This is especially important when consumption permits are limited or unavailable. A site may initially operate with a conservative cycling strategy because it cannot import from the grid. But if that restriction changes later, the asset may need to cycle more frequently. If the physical design cannot support that future operation, the asset owner may miss revenue opportunities or face costly upgrades.

That means design decisions should consider both current and expected future use cases. Cabling, interconnection limits, consumption rights, cycling assumptions, warranties, and long-term service agreements all need to fit together.

The key question is not only: “How will this asset operate today?”

It is also: “How might this asset need to operate in five years?”

‍

BESS Operation Is an Active Balancing Act

Solar operations are mostly about maximizing generation when conditions allow. BESS operation is more dynamic.

Every cycle creates value, but it also contributes to degradation. Every dispatch decision needs to be aligned with operational limits, such as SOC, equivalent full cycles or depth of discharge.

A battery can participate in more revenue streams than a solar asset, including energy arbitrage, capacity markets, frequency services, and other ancillary services. This flexibility is valuable. But it also means operators need to understand the real cost of cycling.

A cycling opportunity may look attractive on paper. But if the revenue does not exceed the cost of degradation, the asset may lose long-term value. This is why BESS operators need a clear view of equivalent full cycles, depth of discharge, state of charge behavior, and degradation trends.

‍

The EMS Is a Critical Control Layer

The energy management system plays a central role in hybrid asset operation. It receives inputs such as weather data, pricing, grid constraints, dispatch schedules, and asset parameters. It then decides how the plant should behave in real time.

That makes EMS selection a strategic decision, not a late-stage technical detail.

A hybrid asset often combines multiple brands, technologies, and control systems. The EMS needs to communicate effectively with the battery management system, power conversion system, and other plant components. If communication is poor or safety limits are not managed correctly, the consequences can be serious.

SOC management is one of the most important examples. The EMS typically acts on the SOC reported by the BMS. But reported SOC is not always the same as true available energy. If the estimate is inaccurate, the operator may dispatch based on energy that is not actually available, which can lead to penalties or underperformance.

‍

More Battery Data Does Not Mean More Insight

BESS generates far more data than a solar plant. A battery can produce 50 to 100 times more data than the solar asset beside it, including cell voltages, string currents, temperatures, alarms, and component-level signals.  

At first, this sounds like a good thing. More data should mean more visibility.

In practice, it is not that simple.

Many of the values that operators rely on are not direct sensor readings. SOC, SOH, and usable energy are outputs from estimation models. They may look like measured values in a data stream, but they are calculated. That means teams may be dispatching, trading, reporting, and making warranty decisions based on numbers without knowing how accurate they are.

This is where standard monitoring tools often fall short. SCADA, BMS, and EMS data can show what is happening at the surface. They do not always explain why it is happening, whether the issue is getting worse, or what action should be taken next.

‍

Hidden Issues Can Quietly Reduce Performance

Some of the most important BESS issues develop gradually. They may not trigger an alarm at first, but they can still reduce usable energy, increase operating costs, or create safety risks.

Common examples include:

• SOC estimation errors, where reported state of charge differs from true available energy  

• Imbalances, where one weak cell, module, or string limits the performance of a larger part of the system  

• Unexpected degradation, where real aging differs from warranty assumptions  

• Cooling faults, where auxiliary loads increase before temperatures rise or alarms appear  

• Recoverable energy losses, where fixable issues reduce the energy the system can actually deliver  

Imbalances are a good example. One weak cell can limit the usable energy of an entire string. The asset owner has paid for that energy, but cannot sell it until the root cause is found and fixed.

‍

Technical Visibility Supports Commercial Decisions

Every technical issue eventually becomes a commercial decision.

If a system is underperforming, asset owners need to know whether the root cause is degradation, imbalance, cooling, unavailable components, control behavior, or supplier-related issues. Without clear evidence, it becomes difficult to decide what to fix, when to dispatch maintenance teams, or how to hold suppliers accountable.

Independent BESS analytics helps create a shared evidence base. Asset managers, operators, OEMs, investors, lenders, and insurers can look at the same facts and make decisions with more confidence.

That matters because BESS performance is closely tied to financial outcomes. Low availability, unplanned downtime, deratings, inaccurate SOC, and hidden degradation can all reduce revenue or increase risk.  

In one example, a shared, independent evidence base let an operator and its OEM jointly recover around 6% of usable energy on a 300 MWh asset — roughly 20 MWh brought back online. That added about $600,000 in annual revenue from capacity the asset already had, and cell balance improved from 51% to 93% within six months.

‍

Analytics Turns Complex Data into Action

BESS analytics is not a replacement for the EMS, BMS, or SCADA. It serves a different purpose.

The EMS tells the asset what to do. The BMS protects the battery at the component level. SCADA collects and displays operational data. Analytics helps operators understand what is really happening inside the BESS and what to do about it.

For example, analytics can help teams:

• Identify underperforming components  

• Improve SOC accuracy  

• Track usable and recoverable energy  

• Detect imbalances  

• Monitor degradation trends  

• Spot potential safety risks earlier  

• Support warranty claims with independent data  

• Plan maintenance before issues become urgent  

This is especially important as portfolios grow. Manual analysis may be possible for one project, but it quickly becomes unmanageable across a fleet. Operators need scalable tools that turn billions of data points into clear, actionable insights.

‍

Want to see what is really happening inside your BESS? Book a 30-minute platform walkthrough with our team. We will show you how independent analytics surfaces hidden capacity, flags issues early, and gives you the evidence base to act on them.