What battery type is best for solar storage in the Caribbean?

LiFePO4 (Lithium Iron Phosphate) batteries are ideal for Caribbean solar storage due to their 80% depth of discharge, 95% efficiency, 5000+ cycle life, and excellent heat tolerance. While more expensive upfront, they offer the lowest cost per cycle and longest lifespan. Lead-acid batteries remain a budget-friendly option for smaller systems.

How many batteries do I need for a solar system?

The number of batteries depends on your daily energy consumption, desired days of autonomy, battery type, and system voltage. For example, a home using 15 kWh/day wanting 2 days of autonomy with LiFePO4 batteries at 48V would need approximately 8-12 batteries depending on individual battery capacity. Use our calculator for an accurate configuration.

How does temperature affect battery capacity?

Battery capacity decreases as temperature drops below 25C (77F). At 10C, capacity drops by approximately 19%, and at 0C by 40%. In the Caribbean, high ambient temperatures (25-35C) mean minimal temperature derating, but batteries should be kept in ventilated, shaded locations to prevent overheating and premature degradation.

Battery Bank Calculator - Solar Storage & Backup Sizing

New to this? Plain-English guide

kWh (kilowatt-hour) — a unit of stored energy. One kWh runs a fridge for roughly a day or a fan overnight. Your battery bank's size is measured in kWh.

Days of Autonomy — how many days the batteries should power your home with no sun and no grid. 2 days is typical for solar; 1 for simple backup.

Depth of Discharge (DoD) — how much of the battery you actually use. Draining a battery completely shortens its life, so lead-acid is kept to ~50% and lithium to ~80-90%.

LiFePO4 vs Lead-Acid — the two common battery families. LiFePO4 (lithium) costs more up front but lasts years longer and uses more of its capacity; lead-acid is the budget option.

System Voltage (12/24/48V) — how the batteries are wired together. Bigger systems use 48V because it needs thinner cables and wastes less power. The calculator picks sensible defaults.

MPPT vs PWM — two types of solar charge controller. MPPT squeezes 20-30% more energy from the same panels and is worth it for anything but the smallest setups.

Energy Requirements

Daily Energy Consumption (kWh)

Days of Autonomy

Battery Configuration

Battery Type

DOD: 80% | Efficiency: 95% | Cycle Life: 5,000 | ~$500/kWh

Individual Battery Voltage

System Voltage

Battery Capacity (Ah)

Capacity (Ah)

Max Depth of Discharge (%)

Temperature (°C)

Charging Source

Charge Controller

Solar Panel Array Wattage (W)

Currency

Project Management

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Calculation Method: Bank sized for required energy storage with temperature derating and DOD limits. Batteries arranged in series to match system voltage, then paralleled for capacity. Charging time based on source power and 85% charging efficiency. Battery life estimated from cycle count and usage pattern.

WattWorks Design - Caribbean Solar & Battery Experts: Serving Jamaica and the Caribbean with professional battery bank design, solar storage systems, and off-grid solutions. Need a custom battery system design? Visit WattWorks Design

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Battery Bank Guide

Battery Type Comparison

Type

DOD

Eff.

Cycles

$/kWh

Lead-Acid FLA

50%

85%

800

$150

AGM

50%

87%

1,000

$250

Gel

50%

85%

1,200

$300

LiFePO4

80%

95%

5,000

$500

Depth of Discharge (DOD)
DOD is the percentage of battery capacity that is used before recharging. Deeper discharge cycles reduce battery life significantly. Lead-acid batteries should never be discharged below 50% for acceptable lifespan, while LiFePO4 can safely go to 80% or even 90% in emergencies. Running batteries to 100% DOD will dramatically shorten their life.

Temperature Effects on Battery Capacity

Temperature

Capacity Factor

25°C (77°F)

100% (baseline)

20°C (68°F)

96% (1.04x oversize)

15°C (59°F)

90% (1.11x oversize)

10°C (50°F)

84% (1.19x oversize)

5°C (41°F)

77% (1.30x oversize)

0°C (32°F)

71% (1.40x oversize)

Charge Controller Types

PWM (Pulse Width Modulation)
• Lower cost, simpler design
• Panel voltage must match battery voltage
• Best for small systems under 200W
• 75-80% effective charging efficiency

MPPT (Maximum Power Point Tracking)
• 20-30% more efficient than PWM
• Handles higher panel voltages (steps down to battery voltage)
• Best for systems over 200W
• Essential for 48V battery systems with higher-voltage panel strings

Caribbean Solar Storage Considerations
• High ambient temperatures (25-35°C) — batteries need ventilation and shade
• Tropical humidity can corrode lead-acid terminals — use dielectric grease
• Hurricane season (June-November) — battery enclosures should be waterproof and secured
• High solar irradiance (5-6 PSH) means faster charging and more daily cycles
• Salt air in coastal areas accelerates corrosion — sealed batteries (AGM/Gel/LiFePO4) preferred
• Power grid instability in some Caribbean islands makes battery backup essential

Series vs Parallel Wiring
• Series: Increases voltage, same capacity. E.g. 4 x 12V 200Ah = 48V 200Ah
• Parallel: Increases capacity, same voltage. E.g. 3 x 12V 200Ah = 12V 600Ah
• Series-Parallel: First wire series strings for voltage, then parallel strings for capacity
• Keep parallel strings to 4 or fewer for lead-acid; LiFePO4 can handle more with BMS

Disclaimer: This calculator provides estimates for preliminary battery bank sizing. Actual performance depends on specific battery models, charge/discharge rates, ambient conditions, and system configuration. Always consult a qualified electrical engineer or solar installer for detailed system design and installation.

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Total Battery Capacity Required

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Battery Bank Configuration

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Total Batteries Needed

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Battery Bank Voltage

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Battery Bank Capacity

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Usable Capacity

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Charge Controller Size

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Estimated Charging Time

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Estimated Battery Life

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Estimated Cost

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Total Bank Weight

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