Charge Controller

(1)

Figure 3

General c

onfigura

tion of the

MPPT solar charge

controller

(2)

Trusted by over 1 million members

Try Scribd FREE for 30 days to access over 125 million titles without ads or interruptions!

Start Free Trial

Cancel Anytime.

(3)

Why do I need one?

A charge controller, or charge regulator is basically a voltage

and/or current regulator to

and/or current regulator to keep batteries from overcharging.

keep batteries from overcharging.

It regulates the voltage and current coming from the

It regulates the voltage and current coming from the solar panels

solar panels

going to the battery.

Most "12 volt" panels put out about 16 to 20 volts, so if there is no

regulation the batteries will be

regulation the batteries will be damaged from overcharging.

damaged from overcharging.

Most batteries need around 14 to

(4)

Cancel Anytime.

(5)

Do I always need a charge controller?

•

Not always, but usually. Generally, there is no need

for a charge controller with the small maintenance, or

trickle charge panels, such as the 1 to 5 watt panels.

•

A

A rough rule is that if the panel puts

rough rule is that if the panel puts out about 2

out about 2

watts or less for each 50 battery amp-hours, then you

don't need one.

(6)

Cancel Anytime.

(7)

Why 12 Volt Panels are 17 Volts

•

The obvious question then comes up - "why aren't panels just

made to put out 12 volts".

•

The reason is that if you do

The reason is that if you do that, the panels will provide power

that, the panels will provide power

only when cool, under perfect conditions, and full sun.

•

This is not something you can count on in most places. The

panels need to provide some extra voltage so that when the sun

is low in the sky, or you have heavy haze, cloud cover, or high

temperatures*, yo

temperatures*, you still get

u still get some output from the panel.

some output from the panel.

•

A fully charged "12 volt" battery is around 12.7 volts at rest

(around 13.6 to 14.4 under charge), so the panel has to put out

(8)

Cancel Anytime.

(9)

Charge controls come in 3

Charge controls come in 3 general types

general types

•

Simple 1 or 2 stage controls:

•

which rely on relays or shunt transistors to control the voltage in one

or two steps.

•

These essentially just short or disconnect the solar panel when a

certain voltage is reached

•

3-stage and/or PWM :

Morningstar, Xantrex, Blue Sky, Steca, and

many others.

•

PWM stands for Pulse Width Modulation. PWM is often used as

one method of float charging. Instead of a steady output from the

controller, it sends out a series of short charging pulses to the battery

(10)

Cancel Anytime.

(11)

3-stage and/or PWM :

The

The SC30

SC30

uses Pulse Width Modulation (PWM) charge voltage

control. When battery voltage is below the present charge voltage

setpoint the PV module is continuously connected to the battery to

deliver maximum charge current.

Once the battery recovers sufficient charge for voltage to rise to

the charge voltage set point, charge current must be reduced to

regulate battery voltage or voltage would continue to increase.

When a reduction in charge current is necessary the PWM control

system reduces average current delivery by rapidly connecting and

disconnecting the PV module at a fixed frequency of 50Hz.

(12)

Cancel Anytime.

(13)

Cancel Anytime.

3-stage and/or PWM :

If only 80% of the available PV current is required to hold battery

voltage at set point the PV is connected (or turned on) for 80% of the

time and remains off for 20% of the time.

The control system varies or

The control system varies or “modulates”

“modulates” the ON time

the ON time “pulse

“pulse width”

width”

percentage as necessary to control battery voltage, hence the term

(14)

Cancel Anytime.

(15)

Cancel Anytime.

Maximum power point tracking

Maximum power point tracking (MPPT)

(MPPT)

•

Maximum power point tracking

(MPPT), such as those made by Midnite

Solar

Solar, Xantrex,

, Xantrex, Outback Power, Morningstar and others.

Outback Power, Morningstar and others.

•

Maximum Power Point Tracking is electronic tracking - usually digital. The

charge controller looks at the output of the panels, and compares it to the

battery voltage.

•

(16)

Cancel Anytime.

(17)

Cancel Anytime.

Maximum power point tracking

Maximum power point tracking (MPPT)

(MPPT)

•

MPPT

MPPT or

or Maximum Power Point Tracking

Maximum Power Point Tracking is algorithm that included in

is algorithm that included in

charge controllers used for extracting maximum available power from PV

module under certain conditions.

•

It then figures out what is the best power that the panel can put out to charge

the battery. It takes this and converts it to best voltage to get maximum AMPS

into the battery.

In a discharged battery, the pulses would be very long and almost continuous,

(18)

Cancel Anytime.

(19)

(20)

Cancel Anytime.

(21)

Cancel Anytime.

•

inverter changes DC voltage to

inverter changes DC voltage to standard

standard AC voltage. Battery

AC voltage. Battery

powered inverters are available for 12,

powered inverters are available for 12, 24, and 48 volts DC. A

24, and 48 volts DC. A

few inverters are also available for 32 and 36 volts on special

(22)

Cancel Anytime.

(23)

Cancel Anytime.

(24)

(25)

Cancel Anytime.

(26)

(27)

Cancel Anytime.

(28)

(29)

Cancel Anytime.

(30)

(31)

Cancel Anytime.

(32)

(33)

Cancel Anytime.

(34)

(35)

Cancel Anytime.

(36)

(37)

Cancel Anytime.

(38)