PV DESIGN 101

Solar PV System 101

How solar works: The Basics

Solar energy

• Solar energy is, simply, energy provided by the sun.

This energy is in the form of solar radiation, which
makes the production of solar electricity possible.
Electricity can be produced directly from
photovoltaic, PV, cells. (Photovoltaic literally means
“light” and “electric.”)

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Solar ng Pilipino / Solar Power Philippines

Basic Terms

• Power

• Power is an AMOUNT of energy. It’s the

measurement of energy, measured in kilowatts
(kW). Power is measured in an instant. Most of the
sizing done in solar PV design (conductors,
inverters, fuses, etc.)

• Power (watts) = current (Amps) X voltage (volts)

• Energy

• Energy is the is the actual work done by power. It is

measure in kilowatt-hours (kWh). Consumers pay
for kWh. It’s a measure of power over time.

• Power (kW) X Time (hours) = Energy (kWh)

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Solar ng Pilipino / Solar Power Philippines

• Current

• Electricity is the flow of negatively charged

electrons. The current is the amount of negatively
charged electrons in a specific part of a circuit. It’s
measured in amps/amperes.

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Solar ng Pilipino / Solar Power Philippines

• Voltage

• Voltage is a measure of the force or pressure of the

electric current in a circuit. It’s measured in volts.

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• Resistance

• Electrical resistance is the resistance of the flow of

electricity through a conductor. It does not reduce
the current flow of electrons (how many electrons
there are in the circuit), but it does reduce the
voltage (how fast they’re going). It is measured in
ohms.

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Solar ng Pilipino / Solar Power Philippines

• Series Circuit

• A series circuit is when one negative and positive of

each power source or appliance are connected
together.

• Remember, CURRENT is constant and Voltage ADDS

in series circuits.

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Solar ng Pilipino / Solar Power Philippines

• Parallel Circuit

• In a parallel circuit, all of the positives are

connected together and the negative are
connected together, each separately.

• In parallel circuits, CURRENT ADDS and voltage

stays constant.

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Solar ng Pilipino / Solar Power Philippines

• AC Current

• AC refers to alternating current. It refers to

electrical systems where the voltage and current
are constantly changing between positive and
negative. A complete “cycle” is completed when
when the current reaches returns to either the
peak or trough of the wave. Frequency is measured
in hertz (Hz) and is measured in number of cycles
per second.

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Solar ng Pilipino / Solar Power Philippines

• DC Current

• DC stands for direct current. DC is the type of

electricity where the voltage and current stay
constant over time. Typical DC applications are
batteries, solar modules, and wind turbines.

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Solar ng Pilipino / Solar Power Philippines

• Voc: Volts open circuit is the maximum voltage a

solar module can ever make when it has no load on
it.

• Vmp: Volts maximum power is the reading of the

maximum volts a module can produce when under
load under standing testing condition, STC,
irradiance levels (1000 W / M2) .

• Isc: Amps short circuits it the maximum amount of

amps that a solar module could produce.

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Solar ng Pilipino / Solar Power Philippines

• Imp: Amps max power, like volts max power, is the

current point on the power curve when the module
is producing maximum power.

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Solar ng Pilipino / Solar Power Philippines

Why we need Solar Energy Setup?

• Saves you money
• After the initial investment has been recovered, the energy from the sun is
practically FREE.
• Financial incentives are available form the government that will reduce your
cost.
• Environment friendly
• It's not affected by the supply and demand of fuel and is therefore not
subjected to the ever-increasing price of gasoline.
• Solar Energy is clean, renewable (unlike gas, oil and coal), sustainable and
helping to protect our environment.
• It does no pollute air.
• • Therefore Solar Energy does not contribute to global warming, acid rain or
• smog. It actively contributes to the decrease of harmful green house gas
• emissions. By not using any fuel, Solar Energy does not contribute to the cost
• and problems of the recovery and transportation of fuel or the storage of
• radioactive waste. Con

Building Solar Setup is not

Cheap

Prioritize what you NEED

How much is your budget?

Save energy first before shifting to
Solar Energy

• Replace your existing old lighting devices into LEDs

• Clean your aircon / electric fan regularly

• Turn off unwanted electric appliances

• Set the refrigerator to minimum acceptable settings

• When buying new appliances of your approved

budget (my own opinion)

• Buy LED TV instead of LCD TV or CRT TV
• Buy Inverter type appliances like Ref, Aircon or Washing

Machine

• Buy Laptop instead of Desktop computers
• Buy Induction type cooker instead of Conventional cooker

Save energy first before shifting to

Solar Energy

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Solar ng Pilipino / Solar Power Philippines

Using Switch to cut the circuit

Basic Electricity and Electronics

Using Circuit Breaker to cut the circuit automatically

when the flow of current is more than what is required

Basic Electricity and Electronics

Positive (+)

Negative (-)

Circuit Breaker

Basic Electricity and Electronics

Conductor

is an object or type of material that
permits the flow of electrical current
in one or more directions. (Example,
wires, metal objects

Insulator is a material whose internal electric

charges do not flow freely, and
therefore make it very hard to
conduct an electric current.
(Example: rubber, plastic, glass

Basic Electricity and Electronics

Electrical Wire – conductor with insulator

Basic Electricity and Electronics

Choosing the right wire for Solar Setup

-Thickness of wire depends maximum
amount of current that will flow in a circuit.
It also depends on the total length of the
wire will run from end to end.
-Thickness is measure in mm2 or AWG

-Insulator of wire depends on the operating
voltage, working condition (i.e. inside or
outside use, exposed to extreme weather,
UV protection)

Wires

Royal Cords – commonly used for connecting Solar Panel to Solar Charge Controller

Speaker Wires– commonly used for
connecting Batteries to Solar
Charge Controllers and DC Loads
Minimum wire gauge should be
AWF #16

Use locally manufactured wires

Basic Electricity and Electronics
Amps – Length – Size

Basic Electricity and Electronics

Series Circuit

A series circuit is a circuit where there is
only one path from the source through all
of the loads and back to the source

The current is the same on all the
components

The voltage on each load may be different
with each other.

Basic Solar Setup
Grid Tie

Grid Tie Inverter

is a power inverter that converts direct current (DC) electricity into alternating current (AC) with an
ability to synchronize to interface with a utility line. Its applications are converting DC sources such
as solar panels or small wind turbines into AC for tying with the grid.

Panel Requirements

- Max Power
- Max Voltage

Grid Tie Inverter

- Max Power
- Max Voltage
- AC Output
- Frequency

Caution:
AC Utility Meter might rotate
in reverse direction if you
harness more energy than what
you consume. Energy Export

Electric Meter

Adding more Grid Tie Inverter on your household

Caution:
AC Utility Meter might
rotate
in reverse direction if you
harness more energy
than what
you consume. Energy
Export

PV Power = GTI Power

Basic Solar Setup
Off-Grid

Basic Diagram of Solar Off-Grid Setup

Solar Panel

Charge Controller

Positive

Negative

Battery

DC Loads

DC-AC
Power
Inverter

220Volts AC

Fuse or Circuit
Breaker

Basic Solar Energy components
Components

Solar Panel Specifications

Solar Charge Controllers (rated in Amps and Voltage)

PWM – Pulse Width Modulation Solar Charge Controller

Solar Charge Controllers

MPPT – Maximum Power Point Tracker Solar Charge Controller

Battery for Solar Setup

Deep Cycle Battery is the recommended type of battery
for Solar Setup

A deep-cycle battery is a lead-acid battery designed to be regularly deeply
discharged using most of its capacity

Common Types:

FLA – Flooded Lead Acid Battery

VRLA – Valve Regulated Lead Acid Battery

- AGM
- Gel Cells

Battery for Solar Setup

Flooded Lead Acid Battery

Battery for Solar Setup

Valve Regulated Lead Acid Battery

Battery Capacity and Rating

Battery is rated by its voltage and Ampere Hour at a discharge rate in hours

i.e. XYZ Flooded Lead Acid Type battery
-12 volts

-120 Ampere-hour

-20 hour discharge rate

-If the discharge rate is not specified, it is assumed to be 20 hour rate

How to calculate for the battery requirements?

-Know the average amount of current usage in Amperes

-Know the average period of usage of a load in hours

Battery Capacity = Ampere x Hours = Ampere-Hour = AH

Deep Cycle Battery Specifications

Battery Capacity and Rating

State of Charge SOA - measures energy left in a battery
Depth of Discharge DOD- is an alternate method to indicate a battery's SOA
*** In practice, batteries should be maintained above of 50% DOD

For Most common Deep Cycle Batteries

Battery Charging using Solar Energy

12.X Volts
Battery was used
14.2 - 15 Volts

13.3 – 13.8Volts
Sun Goes down
12.7 Volts
No Load

Power Inverter

It is a device that converts DC to AC

i.e. Power Inverter that converts 12V DC to 220V AC

Power Inverter is rated:

Input voltage (i.e 12V DC)
Output Voltage (220V AC)
Output Frequency (60Hz)
Max Power Output (i.e 1000Watts)
Surge Power Output (i.e 2000Watts)
Waveform: (Pure Sine / Modified Sine/ Square)

Sine Wave

Modified Sine Wave

Square Wave

Power Inverters

Sizing Up your Solar “Off-Grid “setup

Sizing Up your solar setup

What are the loads you want to be powered by your Solar setup?

- Lights
- Electric Fan
- TV
- Refrigerator
- Aircon?????

What are the power requirements of each appliance and how long you want
use them in a day?
-Lights 30 watts / 10 hours

-Electric Fan

50 watts / 8 hours

-TV

70 watts / 4 hours

Decide which Solar System voltage you want to operate
-12 volts (Most common setup, cheaper charge controller and inverter)

-24 volts (Expensive inverter)

-48 volts (Expensive charge controller and inverter)

Sample Sizing and Computations

• 30 watts light / 10 hours
• 50 watts electric fan / 8 hours
• 70 watts TV / 4 hours

What are the required Solar Components?
(Panel / Charge Controller / Inverter / Battery)

Assumptions

5 hours full sunlight in a day
PWM Charge Controller (0.7 efficiency)
Use 50% Depth of Discharge of the

battery

12 volts System Setup

Sample Computations

Always remember: Energy In = Energy Out

Energy Consumption = Energy Required

Energy that you are about to consume is equal to the required solar energy
you need to harness

Energy about to consume in a day:

30 watts light @ 10 hours usage

50 watts Electric fan @ 8 hours usage

70 watts TV @ 4 hours usage

Formula:

Energy Consumption = Power input x No of hours usage

Sample Computations

Total Energy consumption = 300 + 400 + 280 = 980 Watt-hour

Energy consumption of light = 30 watts x 10 hours = 300 Watt-hour

Energy consumption of Efan = 50 watts x 8 hour = 400 Watt-hour

Energy consumption of TV = 70 watts x 4 hours = 280 Watt-hour

Sample Computations

Total Energy that is about to consume is 980 Watt-hr

Battery Requirements:

- For this example, we decide to use 12 Volts System

Battery Capacity = Energy to be consumed divided by System Voltage

Battery Capacity = 980 Watt-hour divided by 12 Volts = 81.67 Ampere-hour

consider adding margin so battery will stay up to 50% Depth of Discharge

Total Battery Capacity = Battery capacity x 2 = 81.67AH x 2 = 163.33AH or higher

Sample Computations

Solar Panels Requirements

- Assumption: 5 hours full sun exposure

Solar Power requirements = Total Energy Consumption divided by hours of Sun

Exposure

Solar Power requirements = 980 Watt-hr divided by 5hr = 196 Watts

Assuming PWM SCC will be used. Add a 0.7 efficiency factor

Total Power Panel requirements = Solar Power divided by 0.7

Total Solar Power requirements = 196 divided by 0.7 = 280 Watts or higher available

Panel (i.e 3x100watts Solar Panel)

Sample Computations

Solar Charge Controller requirements

Required Solar Charge controller:

12 volts

20Amps

Solar panel specs:

Pmax = 3x100 Watts

Vmax of 12 volts panel is usually around 18Volts

Maximum current from Panel = Pmax divided by Vmax

Maximum Current from Panel = 300 divided by 18Volts = 16.66Amps

Sample Computations

Power inverter requirements

Assumptions: All appliances will be operated at the same time

Total power = 30 Watts + 50Watts + 70 Watts = 150Watts

Maximum battery current consumption

Current = 150Wattss / 12Volts = 12.5Amps

Inverter specs:

300 Watts / 12 Volts

For safety margins, double the power requirements

Inverter specs = 150 Watts x 2 = 300Watts

(Note for large motorized appliances such as aricon and ref, multiply the

power by 3 for surge power during starting)

Wire Size to be used
PV to SCC and Battery to Inverter

Consider the length and current to get the right size
of wire

PV to SCC = 16.67 Amp
What is the Length?

Batt to Inverter = 12.5 Amp
What is the Length?

Summary

• Save electricity costs

• Backup power

• Both

• Green Energy