Solar power is a free source of energy.
You can use this free and unlimited energy
source to run the load in your house and can
also charge batteries.
The electricity that you were using for both
these work, you can save money on that.
To use solar power, you need to install solar
power system in your house.
There are three types of solar power systems
- DC system, On grid and Off grid solar system.
In this video, we will understand how DC system
works.
DC system is an innovative and environmental-friendly
home lighting solar solution.
It is especially designed for areas where
there are frequent power cuts or areas where
electricity is not at all available.
Before understand DC solar system, it is very
important to understand what is DC or direct
current.
There are two types of electric current- Alternating
current or AC and direct current or DC.
An electric power house produces AC.
The supply coming from power station to your
house is AC.
The appliances at home like TV, fan, light
are normally AC.
The electricity created by sun and the power
stored in battery is DC.
You will be surprised to find out that if
you install DC power system rather than the
AC power used in your house, then you can
save around 70% on electricity as compared
to AC.
Not only this but if you run DC appliances
from the battery that you were using to run
the AC appliances in your house, then you
will get three times more backup from the
battery.
You don't believe it?
But this is true.
To know the benefits of using DC power and
disadvantages of using AC power, we will have
to understand the waveform.
As we saw, AC means alternating current which
means current and voltage keeps changing directions.
So the waveform of AC supply in one cycle
will alternate from positive to negative.
DC means direct current which means current
and voltage are flowing in the same direction.
The waveform of DC supply never flows in the
negative direction which means that DC supply
has minimum loses so that DC appliances consume
less power as compared to AC appliances.
For example.
let's assume that we want to compare a 54
inches DC fan and a 54 inch AC fan.
To calculate the power consumption of both
these appliances, there is a simple formula
P=VxI.
If we want to calculate the consumption of
DC fan, so we will put V as 12V in the formula
because we are getting 12V DC from the battery
and DC fan consumes around 2.08 A current.
So according to the formula, P=12X2.08 = 25
W. Now if we calculate the power consumption
of AC fan, we will put the value of V as 220V
because we are getting 220V from mains and
AC fan consumes around 0.36A current from
mains.
Then according to the formula, P=220X0.36
= 80W.
From this example, you can see that a 54 inch
DC fan consumes 25W power whereas a 54 inch
AC fan consumes 80W power which shows that
if we use DC appliances, we can save 70% more
on power and since power consumption is less,
then backup time will increase.
Due to 70% less power consumption, we get
three times more backup and helps in saving
on your monthly electricity bill.
Now we will understand another benefit that
comes out of running DC appliances on DC supply.
Let's assume that you have a normal inverter
at house which converts the AC supply coming
from mains to DC supply and charges batteries
and after that converts the DC supply stored
in the battery to AC to run load.
There is some energy loss in this AC to DC
and DC to AC conversion because whenever one
energy form is converted into another energy
form, there is energy loss in the form of
heat or switching loss.
Therefore the load connected to the inverter
consumes extra power.
But these loses are not present in a DC system
because in this system, there is no form of
energy conversion like AC to DC or DC to AC.
This system charges the batteries with DC
power only and runs the load also on DC power
so that a DC system is way more efficient
than a normal system.
You must have understood the benefits of using
DC power.
Now, we will see how a solar DC system works.
To install a DC system at home, you need solar
panels, batteries and DC load.
DC system uses the power coming from solar
panels and intelligently charges batteries
and runs DC load.
This DC system is available in 800VA/12V.
You can run three DC fans, one DC LED TV and
three or four DC LED lights with this.
As we told earlier, all these appliances are
DC.
Hence their power consumption is very less
as compared to AC appliances.
If ever the power received from solar is not
enough to charge the battery, then you can
easily charge the batteries connected to your
system via mains.
Apart from this, there are two charge controllers
in DC system that are inbuilt.
12V/10amp MPPT solar charge controller.
This one controls the uncontrolled power from
solar panel and efficiently charges the battery.
Second one is 12V/10amp grid charger which
charges the battery from mains supply.
But mains connectivity with the system happens
only then, when the battery connected with
the system and the current coming from solar
panel goes below a preset limit.
Due to this feature, mains supply is minimally
utilized and results in maximum savings.
Let us understand this concept in detail.
Let us assume that we have connected the 
DC system to 12V/120AH battery 
and 120 W solar panels as well.
This 12V battery's boost voltage will be 14.4V
which means that at 14.4V, battery will get
fully charged.
For 120 AH battery to charge, it requires
around 10 amp current.
DC system draws 10 amp from solar to completely
charge the battery but if the current coming
from solar is 4 amp or less and the battery
voltage goes below 12,5, then DC system will
get connected to mains and the batteries will
get charged from mains.
As the solar power becomes available again,
then DC system will charge batteries from
solar.
Now we will understand the front panel of
DC system.
There is an LCD display at the front panel
of DC system and there are three LED indication
lights provided below it.
You can check different parameters of the
system on LCD screen like Rupees Savings,
Battery Voltage, Solar Voltage and Current,
Solar Charge Controller On/Off, Grid Charger
On/Off, MPPT Equalization On.
Apart from this, the LED indications lights
provided below LCD display glow in various
conditions.
First indication is when the battery is getting
charged from mains, then mains charging on
LED will glow in green colour and after that
when the battery charges from solar, then
solar charging on LED will blink in green
and when battery will be fully charged from
solar, then solar on LED will continuously
glow.
When the battery connected to the system discharges
and goes in low condition, then the third
LED will continuously glow in red colour.
Apart from this, there is a mobile charging
port as well in the DC system through which
you can charge your mobile phone by solar
power with the help of a USB cable.
Now we will understand some important protection
features in DC system.
There are two fuses provided in DC system
for protection - AC fuse and DC fuse.
First we will understand AC fuse.
In DC system, there is an AC fuse of 6.5 amp
provided at the side panel of the system.
If the input current coming from mains is
more than 6.5 amp, then AC fuse will blow
and keeps the system protected.
On the other side panel of the system, a 30
amp DC fuse is provided.
If for some reason, there is a reverse connection
with the DC system, then DC fuse will blow
and will keep the system protected.
