Solar Heater Size Formula:
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Definition: This calculator estimates the required size (area) of a solar water heating system based on daily hot water needs, solar insolation, and system efficiency.
Purpose: It helps homeowners and installers determine the appropriate solar collector area needed to meet hot water demands.
The calculator uses the formula:
Where:
Explanation: The daily hot water requirement is divided by the product of insolation and efficiency to determine the necessary collector area.
Details: Correct sizing ensures adequate hot water supply while avoiding excessive costs from oversized systems or insufficient hot water from undersized systems.
Tips: Enter your daily hot water use in liters, local solar insolation (default 4.5 kWh/m²), and system efficiency (default 0.5). Efficiency must be between 0 and 1.
Q1: How do I determine my daily hot water use?
A: Estimate based on household size (50-80L per person) or measure actual usage from your water heater.
Q2: Where can I find local insolation values?
A: Check solar maps from government agencies or use 4.5 kWh/m² as a general average.
Q3: What affects system efficiency?
A: Collector type (flat plate vs evacuated tube), installation angle, shading, and heat loss factors.
Q4: Should I round up the calculated size?
A: Yes, it's recommended to round up to the nearest standard collector size available.
Q5: Does this account for seasonal variations?
A: No, size for your highest demand or lowest insolation period if you need year-round performance.