1. Prepared By :-
Sagar paneliya (17MSE011)
Photovoltaic Power Plant Engineering
2. Junction Box
Top Company Manufacturing Inverter
Selection Criteria for Inverter used in Rooftop or Megawatt Scale Solar Plant
Deciding Inverter for Rooftop Solar Power Plant
Types of Inverters
Basic Working And Application
3. Basic Principle And Application
A power inverter, or inverter, is an electronic device or circuitry that changes
direct current (DC) to alternating current (AC).
The input voltage, output voltage and frequency, and overall power handling
capacity depends on the design of the specific device or circuitry.
In Solar Plant, It Is use for converting DC current which is produced from solar
panel to AC current which is used for Load current.
7. Solar panels are installed in rows and This row connected with one small inverter called
“string inverter ”
For example if you have 25 panels you may have 5 rows of 5 panels. So 5 strings are
connected to 5 string inverter.
Each string carries the DC power the solar panels produce to the string inverter where it’s
converted into usable AC power Depending on the size of the installation, you may have
several string inverters each receiving DC power from a few strings.
8. Lower balance of systems costs.
Lower ongoing maintenance costs (e.g., no fans or air filters).
Simpler design and modularity
string inverters is better for systems with different array angles
Fewer arrays are impacted with one inverter failure.
9. Higher DC watt unit cost.
Newer and less field-tested product
More inverter connections.
Maintainace Cost increases
Requires more distributed space to mount inverters.
11. Central inverters are similar to string inverters but they are much larger and can support
more strings of panels.
Instead of strings running directly to the inverter, as with string models, the strings are
connected together in a common combiner box that runs the DC power to the central
inverter where it is converted to AC power.
Central inverters require fewer component connections, but require a pad and combiner
box. They are best suited for large installations with consistent production across the
12. Lower DC watt unit cost.
Fewer component connections.
Proven field reliability.
Easy to monitor
Optimal for large systems where production is consistent across
13. Higher installation cost (e.g., inverter pad work).
Higher DC wiring and combiner costs.
More inverter connections.
Difficult to find Problem when highest producing strings within a range and block
the production of lower producing strings outside of that range.
Less optimal for systems with different array angles and/or
Microinverter systems are designed to allow for individual per-panel
Most high quality microinverters have undergone rigorous testing in
extreme weather conditions
Microinverters convert DC power to AC instantly, eliminating the exposure to
high voltage DC electricity.
Typically, microinverters have a 15-year warranty opposed to 5 years for
Suitable for Residential
Due to it’s modularity and it’s size, it’s very suitable for residential buildings
where each panel can be differently oriented or have different shading
pattern during the day.
16. Higher Initial Cost
Micro Inverter is been it’s higher initial cost. But it’s cost can be justified in
cases where there are technical challenges in installing a solar array (series
of solar panels) or shading issues that could cause the entire system
As each inverter is independently located below a solar panel, a
communication bus and a common monitoring system
Higher Cost of
As a inverter is below the solar panel, it might be very difficult to replace
the micro inverter due to existing site conditions and might require more
than 1 technician on site to replace.
19. Battery inverters can be installed into homes where no solar PV system exists for
purposes of energy arbitration. It use for when same time electricity cut out and also
in ruler area where no electricity and frequently cutout electricity from grid
Battery is charge by solar power as we know battery give output in DC power so by
inverter it converts to AC Power Just as other inverters. But Due to dual system it
become costly.it cost more than string and micro Inverter.
Due to dual system it become costly.it cost more than string and micro Inverter.
21. In the context of residential (solar + storage) systems, a hybrid inverter
(sometimes referred to as a multi-mode inverter) is an inverter which can
simultaneously manage inputs from both solar panels and a battery bank,
charging batteries with either solar panels or the electricity grid (depending on
which is more economical or preferred).
Because hybrid inverters perform two integral function, they can be less
efficient than standard string or battery inverters
23. Local utility and generator produces sine wave. Because The rotating AC machinery need sine wave
Majority equipment's works on sine wave.
If we supply sinewave input these devices work with full specifications. Motors, microwave ovens
produced full output only when it gets sine wave power.
It is more expensive than others.
24. It is like a square wave but is not exactly a square wave. All equipment's will work fine but will have
low efficiency. So these devices will use more power due to its low efficiency.
25. It is the cheapest inverter. But they are rarely in use. It is used to operate universal
motors without any problem.
27. Let’s Find By Example
Let’s Take Same load
1 tube light – 60 watts For 2 Hrs.
1 CFL - 25 watts For 2 Hrs.
1 fan- 70 watts For 2Hrs.
1 television- 120 watts For 1 Hrs.
Then the power requirement = 2* 60 +2*25+2*70 +1*120
28. So the total power requirement is 430 watts.
Then the power of the inverter is the ratio of power requirement in watts to the power factor (efficiency).
Power of inverter = power requirement / power factor
Most of the inverters have efficiency 60% or 70 % (Or We can Take 1.3 Time of Max load)
Assume power factor =0.7
Then power of inverter = 430/ .7 = 615 VA, the inverter of specific rating can be choose.
Now Select standard Inverter Which is Nearest Power Value Of 615 VA
29. Sine wave inverter is better, because it reduces heating and will increase the longevity of inverter.
The square wave inverter produces a humming sound. This humming sound can be reduced by
using sine wave inverter. The sine wave inverter supply is better than the supply from grid.
Choose the inverter with capacity according to the load.
Like In Summer Overall Voc Is decreases and In winter Overall Voc Is increases so consider
this types condition.
The idle power consumption of inverter must be low.
It must consume low electricity from grid.
30. Most inverters available in market are rated on kVA/VA or Kilo Volt Ampere/Volt
In ideal situations (power factor of 1) 1 VA = 1 Watt. But in real power factor varies
from 0.85 to 0.99
So one can assume 1.18 VA = 1 Watt. So if you have a setup where the total wattage
of the system is 1000 Watts, it means your inverter size required is more than 1180
VA or 1.18 kVA (add some extra to be on a safer side).
31. The Efficiency of an inverter is indicating how much DC power is converted to AC power.
Because Some of the power is lost as heat and some for keep inverter in turn on. The
general efficiency formula is
PAC is AC power output in watts
PDC is DC power input in watts
• High quality sine wave inverters are rated at 90-95% efficiency.
• Lower quality modified sine wave inverters are less efficient - 75-85%.
• High frequency inverters are usually more efficient than low-frequency
32. Efficiency may vary from something just over 50% when a trickle of power is being used, to
something over 90% when the output is approaching the inverters rated output.
A 3 KW inverter may typically draw around 20 watts from your batteries when no AC
current is being used. It would then follow that if you are using 20 watts of AC power, the
inverter will be drawing 40 watts from the batteries and the efficiency will only be 50%.
A small 200W inverter may on the other hand only draw 25 watts from the battery to give
an AC output of 20 watts, resulting in an efficiency of 80%.
35. The combiner box is a device that combines the output of multiple strings of PV modules for connection to the
It is typically used in the larger commercial and utility scale PV power plants (greater than 500kW).
The combiner box commonly houses the input overcurrent protection fuse assemblies for several strings
(from as few as three strings to as many as 52), as well as the combined bus of those inputs into a single main
Mounting on a north facing wall in the shade is recommended, as direct sunlight can significantly increase
internal combiner temperatures, reducing reliability and life of internal components
36. There are several key elements to pay close attention to when specifying or evaluating a string combiner box.
Enclosure = Most string combiners are available in outdoor-rated enclosures,
typically NEMA 3R, 4 or 4X, with NEMA 3R being the minimum requirement.
typical today is a NEMA 4 steel or NEMA 4X non-metallic enclosure.
In high humidity areas, or areas with a large swing in humidity, you might consider adding a condensation or breather
vent that will allow pressure equalization to the enclosure
The enclosure is often one of the more expensive components in the string combiner but it’s important because it
has a direct impact on the life of the combiner.
The enclosure’s mounting position, size and color directly affects the internal temperatures. Lighter colors typically
absorb less solar radiation than darker colors.
37. 1. GEESYS Technologies (India) Privat Limited
2. Yaskawa – Solectria Solar
3. Susten by Mahindra
5. Green Field Solar PVT Ltd.
combiner box manufacturers
38. A photovoltaic (PV) junction box is an important part of the solar panels. The junction box is an enclosure
on the module where the PV strings are electrically connected.
The PV junction box has a simple, but important role: housing all the electric bits on a solar panel and
protecting them from the environment. Wires connect to diodes inside, providing an easy way to link
A junction box has bypass diodes that keep power flowing in one direction and prevent it from feeding
back to the panels.