Outline

• Typical Applications

• System Design Basics– Sizing battery pack

– Sizing solar panels

– Other considerations

• Refrigeration/Air-Conditioning system– Compressor selection

– Designing to reduce loads/power consumption• Fans

• Coils

Outline con’t.

• System Design Considerations

– Compressor type

– Wide voltage range

– Load shedding

– Soft start

– Power management

Solar Powered Vending Machines

Solar Powered Refrigerator

• Pharmaceuticals

• Food

• Marine

• Off-grid applications

Telecom Applications

Battery Bank Cooler

Full Cabinet Air-Conditioner

Typical System Schematic

Solar Array

Fuse

Solar Charge Controller

DC Batteries

Refrigeration orAir Conditioning Equipment

Battery Charger

AC Power or AC/DC Generator

System Design Basics

• Sizing the Battery Pack

– Step 1: Calculate the daily watthour usage

• Ex. 350W x 8 hours = 2,800 watthours

– Step 2: Determine run time between battery recharge

• Ex. 2,800 watthours x 2 days = 5,600 watthours

– Step 3: Determine total battery capacity

• Size for maximum 50% battery usage

• Size for maximum 80% cycle life

• Ex. 5,600 watthours ÷ .5 ÷ .8 = 14,000 watthours

System Design Basics

• Sizing the Battery Pack

– Step 4: Calculate the size of the battery bank in Amp Hours

• Ex. 14,000 watthours ÷ 12 volts = 1,167 amp hours

– Step 5: Determine the quantity of batteries required

• Typical 12V batteries are 105 amp hours

• Ex. 1,167 amp hours ÷ 105 amp hours = 12 batteries

General Considerations

• Must account for battery cycle life

– Typically 80% maximum

• Must consider rate of discharge

– Typically not to exceed 50%

• Masterflux provides a simple

calculator

Current (A): 29

Voltage: 12

Daily Run Time (hr): 8

Days of Runtime between charge: 2

Rate of Discharge Factor (%): 50%

Cycle Life (%): 80%

Total Battery Capacity (watt-Hour): 14000

Battery Bank (Amp-Hour): 1167

Battery Amp-Hour: 105

Total Batteries Required: 12

Battery Calculator

System Design Basics

• Sizing the Solar Array– Divide your daily watthours from Step #1 by solar panel

wattage times the hours of available sun

• Ex. 2,800 watthours ÷ (90 watts • 5 hours) = 7 panels– Assumes a 90 watt panel

– 5 hours average daily sun for mid. latitudes in the U.S.

General Considerations

• Size and output of panels vary

• Average daily sun varies depending on region

• Efficiency of panels vary by type and manufacturer

Other Considerations

• Solar Charge Controller

– Required if using battery backup

– Needs to be sized for the application and voltage

• Generator or Line Connected Power

– Required if there is a limitation on battery bank

– Used for backup power in low sun conditions

• Battery Charger

– Needed for charging batteries in conjunction with line connected power or a generator

Refrigeration or Air-Conditioning

System Design Considerations

• Fan Selection

– ECM fans

– Variable speed and high efficiency

• Coil Size

– Reduce the discharge pressure as much as possible

– Power consumption is directly related to compressor load

• Air flow

– Proper airflow to manage discharge pressures

Variable Speed Compressor Selection

• Since all of our compressors are variable speed, we need to be sure that we pick the correct compressor to fit the application.

• The lowest capacity on the larger compressors will overlap the higher capacity on the smaller compressor.

• However, the efficiency of both will vary throughout the RPM range.

Variable Speed Compressor Selection

• Efficiency• Efficiency drops at lower RPM

• Efficiency drops at higher RPM

• Need to select compressor with the maximum efficiency for the

required RPM range

1800 2300 2800 3700 4500 5300 6500

Efficiency vs. RPM

Example SIERRA Compressor Selection

• Voltage: 24V

• Capacity: 1600 W

• Evap: 7.2°C

•

Compressor SIERRA02-0434Y3 @ 24V SIERRA03-0982Y3 @ 24V

Speed 5300 RPM 2800 RPM

Capacity 1586 W 1668 W

COP 2.05 3.01

Power Input 773 W 554 W

Variable Speed

• Reduces the spikes in

cooling requirements

• Reduces the overall

power consumption

– Internal testing has seen

reductions of up to 30% in

kWh

• Match compressor RPM

to available power

Vo

ltag

e

Current

Panel Voltage vs. Current

Compressor Soft Start

• Reduces the voltage

drop on PV array

• Improved battery life

• Available with:

– CASCADE

– ECLIPSE

– SIERRA

0

5

10

15

20

25

30

35

40

45

0.0 0.4 0.8 1.2 1.6 2.0 2.4 2.8 3.2 3.6 4.0

Cu

rrn

et

Time

Soft Start

Standard Start

Solar Application Voltage Range

• Varies depending on time of day

• Varies depending on cloud cover

• Typical Masterflux Ranges

– 12/24V : 9.6V to 31.5V

– 24V: 19V to 30V

– 48V: 39V to 60V

Wat

ts

Time of Day → solar noon

Load Management

• Vary the maximum compressor RPM to match voltage

• Reduces the risk of a low voltage system shut down

• Critical when operating on solar array only

• Available in CASCADE controllers 1500

2000

2500

3000

3500

4000

4500

12 13 14 15 16 17

Max

imu

m R

PM

Voltage

Load Shedding / Voltage Rise

• Occurs when batteries are fully charged and

switching from generator or line connected power to

the solar array

• No load on the array or batteries

• Voltage on system can spike

• Will cause damage to compressor controller

Voltage Monitoring / Protection

• Monitors input voltage

• Discontinues output if voltage is not within specified range

• Masterflux provides voltage protection for solar, battery, and generator applications

• Protects up to 150V DC spikes

0

10

20

30

40

50

60

70

80

0 10 20 30 40 50 60 70 80

Ou

tpu

t V

olt

age

Input Voltage

Low VoltageCondition

Over VoltageCondition

Operating Envelope

Complete System Controls

• Evaporator and Condenser Fan Controls

• Compressor Control

– Fixed or variable speed operation

• Voltage Monitoring/Protection

– Up to 150V DC spikes

• 24V or 48V operation

Variable Speed DC Compressors and

Condensing Units

• Masterflux offers a wide range of DC powered

variable speed compressors and condensing

units for a variety of applications.