• Sophia Nortje

• Technical Sales Manager

• SolarEdge

• South Africa

Increasing System Efficiency Through

Module Level MPPT –

The Power Optimizer Revolution

Some questions to start with…

250 W 250 W 250 W 250 W = ?? + + +

How much energy is being produced?

= 1000 W

Some questions to start with…

250 W 50 W 250 W 250 W + + +

How much energy is now being produced?

= 800 W or 200 W ?

Some questions to start with…

250 W 50 W

50 W 250 W 50 W

250 W 50W

= = 200 W !

+ + +

How much energy is now being produced?

String Level MPPT

The speed is limited by the performance of the weakest rider…

With string inverters, the power is limited by the performance of the weakest panel…

MPPT on String Level

Now what if we had this picture…

250 W 50 W 250 W 250 W = 800 W + + +

How much energy is being produced?

Module Level MPPT

With personal transmission gear, each rider can maximize individual potential, so the bicycle travels faster!

With power optimizers, each panels performance is individually measured without affecting the others

MPPT on Module Level

Energy loss factors in traditional PV systems

Module Mismatch

10% module mismatch Screenshot shows power

curves of 10 adjacent modules in a string with 10%

mismatch between highest and lowest performing

modules

Mismatch Sources:

Partial Shading

Shading is virtually unavoidable in PV systems and can be caused by nearby obstructions, uneven dirt, cloud fronts, neighboring PV modules and more

Due to central MPPT function and bypass diodes functionality, the power loss due to partial shading is much greater than the actual reduction in illuminated area

Uneven soiling

Just like partial shading, soiling is a reduction in the illuminated area of modules

Soiling can be caused by anything from falling leaves to dust and bird droppings

3%-5% energy loss on mismatch between soiled modules with traditional inverter technology

Module mismatch due to soiling Module mismatch due to snow coverage

Temperature Variances

Temperature difference between modules creates mismatch

Traditional systems lose power on temperature differences

Source: C. Buerhop et al., ZAE Bayern, “The role of infrared emissivity of glass on IR-imaging of PV-plants”, 26th EUPVSEC, 5-9/9/11, Germany

IR-camera reveals: Temperature decreases by 13°C from top to bottom row of modules in this PV plant = 5.6% Pmpp mismatch (∆Pmpp=13°C * 0.43 [%/°C])

Example: Aerial image of PV field

Uneven Aging

Most modules age to an acceptable degree of >80% of the label output But the different rate at which they age introduces aging mismatch

Factory Mismatch

The warranted output power within a power class may vary greatly A standard deviation of +/-3% is sufficient to result in ~2% energy loss with traditional inverters .

Mismatch over time Detail of a 107,9 kWp site in Germany; 415 modules each 260Wp All modules have the same power and all modules are oriented in the same orientation and same angle….

Dec 12 – Apr 15

28 months

Low: 550,65 kWh

943 kWh/kWp

High: 650,66 kWh

1115 kWh/kWp

18,2% deviation

Average 9,1% avoided loss

= 85 kWh/module

35275 kWh avoided loss

FiT: 0,1648 €/kWh

Avoided loss: 5813 € in 28 months

Optimizer Solution and Overview

DC Optimized Inverter Solution

Inverter

Monitoring Portal

Power Optimizer

Smart Module with Power Optimizer

Power Optimizer 2:1 configuration

The solution for increased efficiency

The inverter is simpler and more reliable:

Responsible only for DC to AC conversion, as all other functions are handled separately for each panel by the power optimizers

Small and aesthetic

By displaying real-time performance data, the monitoring portal allows:

Full visibility of your system performance

Automatic alerts on system issues

Easy access from a computer, smartphone, or tablet

1. Power Optimizer 2. Inverter 3. Monitoring Portal

By connecting a DC power optimizer to a PV panel it becomes a smart panel. This allows:

Harvest of up to 25% more energy from each panel

Constant feedback on the performance of each panel

Automatic shutdown of each panel for maximum safety in case of emergency

1 2 3

DC Power Optimizers in Detail

600W-700W Power Optimizers P-5 Series Module Add-On for Commercial Installation

Per-module Maximum Power Point Tracking (MPPT)

99.5% maximum efficiency, 98.8% weighted efficiency

Advanced, real-time performance measurement

Automatic module shut-down for installer and firefighter safety

Embedded by module manufacturers, or connected by installers to c-Si and thin-film modules

Benefit: More Power by Design

Power optimizers enable installation of:

Modules in partially shaded areas

Strings of uneven lengths

Strings in multiple orientations and different roof facets

More modules on the roof

More power & Revenue Traditional inverter: 149.5 kW DC With Optimizers: 200 kW DC 34% added power

Benefit: Future Compatibility

During the lifetime of the system it might be necessary to replace modules (e.g. hail damage, delamination, …)

Flexible design allows to replace modules with different power classes and brands in the same string New power optimizers can be utilized in the same string with older models

Low-cost inverter replacement after warranty 40% less than traditional inverters

MLPE Market

“The evolution from market niche to market success” (GTM Research)

Module-level power electronics (MLPE) predicted to be 5GW by 2017

In 2013 >50% of US residential systems used micro-inverters or DC optimizers

Microinverters mostly limited to Americas

Global Market Share of Top MLPE Suppliers by Capacity Shipped (MW), 2013

Source: GTM Research ,Jan 2014

Comparative Case Studies

More Energy in Commercial Systems

Location: Newton Abbot Leisure Center, UK

Size: 68.8kW

Installation date: March 2013

Modules: 240xCanadian Solar CS6P-245M + 40xCanadian Solar CS6P-250M

Inverters:

Inverter w Optimizers: 3 x SE17K and 1 x SE10K with 280 x P300 power optimizers

String Inverter: 3 x STP 17000TL and 1 x STP 10000TL and 1 x STP8000TL

String Inverter

More Energy in Commercial Systems

Location: Covers Aldershot, UK Size: 39.01kW Installation date: November 2013 Modules: 166 x Azur Solar P235

Inverters: Inverter w Optimizers: 2 x SE17K with 83 x P600 power optimizers String Inverter: 2 x STP 17000TL

String Inverter

THANK YOU