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Worksheet for Designing a Solar System Based on Power Consumption Input fields in Grey
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Copy this sheet for your own use: File->Make A Copy
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Daily Power Consumption Analysis
Solar Power Requirement Analysis (Full Sun)
At AnchorOn Passage
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Average Hours of Sun per Day 5*3*
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ApplianceAmpsHoursHours
Daily AH *1*
Daily AHBattery Charge Inefficiency Factor 1.2*4*
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DCAt Anchor
On Passage
At Anchor
On Passage
Watts of Solar to Replenish Battery Bank Daily
 254.8 551.5
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Refrigeration510105050
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Radar44016
Solar System Design Analysis (MPPT Controller)
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Computer - Laptop4110440Capacity of Each Solar Panel (Watts)130
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Autopilot410040Number of Solar Panels Required2.24.7
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Cabin Lights (LED)1440Number of Solar Panels Installed3
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Nav/Anchor Lights0.2101022
Minimum Capacity of Solar Controller (Amps)
 30.0
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Stereo13333
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VHF Radio0.5101055
Daily Useable Solar Power in Full Sun (Watt Hrs)
 1,755.0
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Instruments1808
Daily Power Drawn from Battery Bank (Watt Hrs)
 1,061.5 2,297.8
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Pressure Water60.250.11.50.6Excess or (Deficit) of Power (Watt Hrs) 693.5 (542.8)
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Phone Charger12222
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Other00Factor for Cloudy Days
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Other00
Solar Efficiency on Cloudy Days (percentage)
30%*5*
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 Total Amp Hours71.5166.6Solar Power Generated on a Cloudy Day 526.5
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Power Drawn from Batteries on a Cloudy Day (Wh)
 535.0 1,771.3
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AC - Equipment powred by an Inverter (Watts)
Number of Continuous Cloudy Days2
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Microwave (Watts)11000.10.110.210.2
Sunny Days to Make Up Battery Draw Down
 1.5 -
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Other0.00.0
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Other0.00.0Battery Capacity AnalysisAmp HrsAmp Hrs
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Windlass *2*0.00.0at Anchoron Passage
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 Total Amp Hours10.210.2
Scenario 1 - Based on Cloudy Days - with Solar
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Ah Drawn from Batteries on Cloudy Days 82.3 272.5
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Total Amp Hours Consumed per Day
81.7176.8% of Battery Capacity Useable50% *6*
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Rated Battery Capacity Required (AH) 164.6 545.0
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Battery Charging Voltage
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Number of Batteries Required (in parallel) 1.4 4.5
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Total Watt Hours Consumed per Day
1,061.5 2,297.8
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*1* AH - Amp Hours - Amps of current consumed in one hour
Scenario 2 - Based on Days of Reserve Capacity (no solar)
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*2* Windlass is often not considered because the engine alternator is running when used
Number of Days of Reserve Battery Capacity
2
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*3* 5 hours avg. is a good estimate for horizontal panels, 7 for panels with tilt & rotate
% of Battery Capacity Useable50%
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See http://www.bigfrogmountain.com/SunHoursPerDay.html for hours in your area.
Rated Battery Capacity Required (AH)326.6707.0
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*4* Charge efficiency factor - Lead Acid ≈ 1.2, AGM ≈ 1.1 , LiFePO4 ≈ 1.04
Rated Battery Capacity (Ah)120
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*5* Solar efficiency - Partly cloudy ≈ 70%, Mostly cloudy ≈ 50%, Very cloudy ≈ 30%
Number of Batteries Required (in parallel) 2.7 5.9
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*6* Useable battery capacity - Lead Acid ≈ 50%, AGM ≈ 60%, LiFePO4 ≈ 95%
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Steps to use this worksheet
Note: This methodology does not take into
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1. Determine the average daily power consumption both at anchor and on passage.
consideration power generation from other sources
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2. Configure the solar system (battery and solar panel inefficiencies are considered).
such as engine alternator, generator, wind generator,
Custom Marine Products
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3. Modify the solar system configuration to accommodate anticipated cloudy days.
fuel cell or shore power.
custommarineproducts.com
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4. Analyze the capacity of the battery bank.
info@custommarineproducts.com 248 705-8337
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