Power inverters or home UPS have been in use in India since quite some time. Thanks to frequent power cuts, home UPS or power inverter industry has done well in India. But with increasing interest in solar
power and solar panels many people are thinking of using Solar Power to
charge the batteries to save electricity drawn from the grid. Having
heard of solar inverter, many people wonder if their existing inverter
system is useful or not. In past, we have got this question many times: what is the difference between solar
inverter and regular inverter?
What is an inverter?
A power inverter or invert is a device
that converts Direct Current (or DC) to Alternating Current (or AC)
using transformers, switching and control circuits. And this is the
basic function of any inverter: be it solar or regular inverter. A home
UPS or home inverter take the DC power from the batteries and convert it
to AC power used by appliances. A solar inverter also does the same if
it is an “Off Grid” solar power system. In case of “Grid Connected” the
DC power is from the solar panels and AC power is given to the grid. (To
know more about “Off Grid” and “Grid Connected” solar power system,
read our article: Solar electric, solar thermal, power generation, inverters, grid, off-grid: clearing the cobweb).
Working of a Home UPS/Inverter
A regular home UPS/inverter system has a
system of inverter and batteries that is connected to the home power
connection. When the power is coming from the grid, the UPS/inverter
system charges the batteries using the power coming from the grid. When
the power is off, the inverter takes the DC power from the batteries and
converts it into AC used by appliances. There is an automated switch in
the system that senses if the grid is not supplying power and switches
the UPS into battery mode.
Working of a Off Grid Solar Powered system
An off grid solar powered system has an
assembly of solar panels, charge controller, batteries and inverter as
shown in the image below. The batteries are charged using solar panels
and the inverter has the same function of converting DC to AC. It can
also have an automated switch to sense if grid is not supplying power
that can change the power source of the connected home from grid to
batteries. Depending on the need the system can be designed to: 1) To
completely rely on solar power 2) Charge the batteries from solar power
when sun is available and from the grid when it is not.
An existing home UPS or Inverter system
can be converted to be used with an off grid powered system by just
adding a switch which can control the change source: solar or grid
(based on availability).
Having said that, to answer the question
posed in the title of this article: there is not much difference
between a solar inverter used in off grid system and a regular inverter.
Working of a Grid Connected Solar Power System
A grid connected solar power system
additionally supplies excess electricity to the grid. People go for this
kind of system when they feel that they have enough space to install
solar powered system and they can sell the extra electricity generated
back to the electricity distribution company.The structure of a
grid-connected system is shown below:
The purpose of the inverter in this kind
of system is also to convert DC (generated from Solar Panel) to AC. But
it additionally needs a MPPT (Maximum Power Point Tracking) feature to
be built in it. Because the voltage generated by Solar Panel varies
depending on the temperature and availability of sun (more on this on
our article: Solar Glossary – photovoltaic, panels, modules, cells, voltage, watt and current),
MPPT enables solar inverters t draw maximum power from the solar
panels. The solar inverter used for grid-connected solution also
includes an anti-islanding functionality to prevent risks to grid in
case there is power failure in the grid.
Conclusion
The basic purpose of any inverter is to
convert DC power to AC power be it solar inverter or regular inverter.
Depending on the situation and setup one may need some additional
features, which can be implemented in existing home UPS/inverters
through simple modifications.
Source of Information
www.bijlibachao.com
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