Professional Tool 2026

BESS Simulator: Battery Viability

Calculate the payback and profitability of storage systems for your solar plant. Analyze revenue from arbitrage, grid services (aFRR) and curtailment capture. Compare LFP vs Flow Batteries technologies.

LFP (Lithium Iron Phosphate)

Efficiency

90%

Life Cycles

6,000

Lifespan

15 years

Degradation

2%/year

System Parameters

Configure your plant and BESS system

PV Plant Power (MW)

Current Curtailment (%)

Energy lost due to grid restrictions (~5,950 MWh/year)

BESS Sizing

Capacity (MWh)

Power (MW)

E/P Ratio: 4.0h discharge

REVIEW PARAMETERS

Estimated Payback

No recovery

Net CAPEX: €4,000,000

Year 1 Revenue€597,140

Arbitrage

€296K

aFRR

€223K

Curtailment

€79K

Total Cash Flow (15y)

-€218K

Captured Curtailment

2,190 MWh/year

BESS Financial Projection

What is a BESS System?

BESS (Battery Energy Storage System) is a battery energy storage system that allows you to store electricity generated by your photovoltaic plant for use when it is most convenient: during price peaks, when there are grid restrictions, or to provide regulation services to the electrical system.

In 2026, more than 15% of new solar plants in Spain include BESS from initial design. The price drop (from 600 €/kWh in 2018 to 180-220 €/kWh in 2026) and increasing curtailment in saturated areas have made storage increasingly attractive.

Technology Comparison: LFP vs Flow Batteries

Characteristic	LFP (Lithium Iron Phosphate)	Flow Battery (Vanadium)
CAPEX (€/kWh)	180 - 220 €	300 - 450 €
Round-Trip Efficiency	88 - 92%	70 - 80%
Life Cycles	6,000 - 8,000	15,000 - 20,000
Annual Degradation	1.5 - 2.5%	< 0.5%
Lifespan	12 - 15 years	20 - 25 years
Optimal Discharge Duration	1 - 4 hours	4 - 10 hours
Best Use	Arbitrage, aFRR, curtailment	Seasonal storage, long duration

Recommendation: For most solar plants in Spain (1-4h discharge), LFP batteries are currently the best option. Flow Batteries will gain market post-2028 for long-duration applications (>6h).

Revenue Sources for a BESS System

Price Arbitrage

Buy/store energy when it's cheap (night, solar surplus) and sell it when it's expensive (late afternoon-evening).

Potential: 5,000 - 15,000 €/year per MWh

Grid Services (aFRR)

Availability for automatic frequency regulation. Requires <1s response and REE certification.

Potential: 50 - 150 €/MW/day

Curtailment Capture

Store energy that REE orders to be reduced due to grid restrictions. Critical in saturated areas.

Recovery: up to 80% of curtailment

💡 Optimal strategy: Combine all three revenue sources ("revenue stacking"). A 50 MW plant with 10 MW/20 MWh BESS can generate ~250,000 €/year combining arbitrage, aFRR and curtailment capture.

When is BESS Installation Worth It?

BESS IS viable if...

✓ Curtailment > 8%/year (lost energy capture justifies investment)
✓ You receive subsidy (30-40% CAPEX from hybridization programs)
✓ Industrial self-consumption with high demand peaks
✓ You can participate in aFRR (REE certification available)

BESS is NOT viable if...

✗ Plant without curtailment (<2%/year) and without subsidy
✗ Only planning price arbitrage (insufficient volatility in 2026)
✗ Small project (<5 MW) without economies of scale
✗ Expensive financing (>6% interest, payback extends >15 years)

Need to calculate your plant's total revenue?

Photovoltaic Investment Calculator →

Want to learn more about BESS technologies?

Complete Guide: BESS vs Flow Batteries →

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