Q0014
Solar plus BESS makes more sense when storing solar creates enough additional value to justify the battery’s lifecycle cost or when storage is required for compliance, connection or reliability. Solar alone is usually preferable when daytime electricity can be consumed directly or exported at an attractive value without causing grid or operational problems.
Adding a battery can improve solar utilisation and reliability, but it also adds cost, losses, degradation, safety obligations and operational complexity. Storage should solve a defined mismatch between when solar is produced and when electricity is valuable.
#### Solar alone is generally stronger when:
#### Solar plus BESS becomes stronger when:
1. Solar output exceeds daytime demand
A battery can capture surplus generation for later consumption rather than exporting it at a lower value.
2. Evening electricity is more valuable
Under Peninsular Malaysia’s time-of-use periods, the peak window extends from 2 p.m. to 10 p.m. on weekdays. Storage can move part of the solar output into the later portion of this window.
3. The facility has a material demand peak
Solar may not consistently reduce maximum demand if the peak occurs during cloudy conditions or after sunset. A dispatched battery can provide more reliable peak reduction.
4. Export is constrained or poorly compensated
Where export value is materially below the avoided import price, storage may increase the value retained by the customer.
5. Firm renewable delivery is commercially required
CRESS distinguishes firm and non-firm supply and provides a current Malaysian application for solar firming with BESS.
6. Regulations require storage
Current SELCO guidance introduces BESS requirements for certain non-domestic solar installations above 72 kWp. Regulatory requirements should be treated as design constraints and checked against the latest rules.
7. Resilience has measurable value
Solar normally shuts down during a grid outage unless the system has compatible islanding, controls and storage. Solar plus BESS can support selected loads, but only if the installation is designed for this purpose.
8. The shared connection is better utilised
A battery may charge during high solar output and discharge when the solar plant is below its connection limit, increasing use of expensive connection infrastructure.
#### The correct comparison
Compare at least three alternatives:
1. Solar alone. 2. BESS alone. 3. Solar plus BESS.
Where relevant, also compare:
The hybrid should be evaluated on incremental value:
> Incremental battery value = value of solar-plus-BESS − value of solar alone
The battery is justified only if this incremental value exceeds its full lifecycle cost and compensates for additional risk.
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