Renewable Energy World - magazine

Подождите немного. Документ загружается.

LARGE SCALE SOLAR SUPPLEMENT - MAY 2011

silicon could reach 370,000 tonnes

next year, up from about 350,000

tonnes in 2010. Huge expansions

have taken place since the 2005

and 2008 shortages, and many

only came on-line last year. Various

small Chinese players are being

forced to shut down production

while the largest established

companies are announcing

capacity increases of as much as

40,000 to 60,000 tonnes by 2012.

For wafers, global production

capacity totalled 30–35 GW in

2010, of which more than 55% was

in China. Germany accounts for

more than 10% of global capacity,

followed by Japan, Taiwan,

Norway and the US.

Crystalline-silicon (c-Si) cell and

module capacity is now mainly

based in Asia. EPIA estimated

global c-Si cell production at 27–

28 GW in 2010. Almost half this

capacity was in China, while Taiwan

produced more than 15%, the EU

more than 10%, Japan slightly less

than 10%, and the US less than 5%.

Module production capacities for

c-Si were estimated slightly higher

at 30–32 GW.

Global production of thin-lm

modules reached 3.5 GW in 2010.

This is likely to increase to more

than 5 GW in 2011 and might

reach 6–8.5 GW in 2012.

Scaled down incentives

Three main factors have driven PV’s

spectacular recent growth. Firstly,

renewable energy is no longer a

curiosity; PV has proven itself to

be a viable energy source in all

regions of the world. Secondly,

price falls have brought PV close

to grid parity in several countries,

encouraging new investors. Finally,

policymakers in key countries

have introduced FiTs and other

incentives that have helped

develop markets, cut prices and

raise investors’ awareness.

Over the last decade, global

installed capacity has multiplied

by 27, from 1.5 GW in 2000 to

39.5 GW in 2010 – an annual

growth rate of 40%. Furthermore,

that growth has proved to be

sustainable, allowing the industry

to develop at a stable rate.

The EU, having overtaken

Japan, is now the clear leader

in both market and installed

capacity, thanks largely to German

initiatives, which have also fed

global expansion. In the rest of

the world, the leading countries

continue to be those that started

installing PV even before the EU.

The market is expanding every

year. In sunbelt countries, falling

prices are bringing PV closer to

grid parity and helping spread

awareness of its potential. But the

nancial crisis and competition

from other energy sources put

pressure on policymakers to

streamline incentives.

‘The currently installed

global PV capacity produces

power equivalent to the entire

electricity consumption of

countries like Greece, Romania

or Switzerland,’ said Ingmar

Wilhelm, EPIA’s president.

‘The evolution of the PV

market in recent years has been

heavily linked to the condence

and vision of... policymakers in

supporting the development of

the technology. Adequate support

policies that have been driving the

markets so far, such as the feed-in

tariffs, must continue and be ever

[continuously] brought in tune with

the declining cost curve of PV.’

For more info, enter 60 at rew.hotims.com

RENEWABLE

ENERGY

WORLD

RENEWABLE

ENERGY

WORLD

__________

LARGE SCALE SOLAR SUPPLEMENT - MAY 2011

The Middle East and North

Africa region (MENA) could be

ripe for developing its massive

potential in concentrating solar

power (CSP), nds a recent

study for the World Bank by the

Fraunhofer Institute for Systems

and Innovation Research (ISI) and

the Fraunhofer Institute for Solar

Energy Systems (ISE).

Solar thermal electricity

generation is on a clearly positive

trend, with new CSP installations

having doubled since 2007,

nds ‘MENA Assessment of

Local Manufacturing Potential for

Concentrated Solar Power (CSP)

Projects,’ a study conducted in co-

operation with Ernst & Young.

By mid-2010, over 800 MW

of CSP plants were in operation.

Although the market is dominated

by the US and Spain, a boom

fuelled by national incentives is

now seeing projects appear in

Australia and in Asia and MENA.

The latter offers the greatest

global application potential,

found the study. In addition,

European plant manufacturers

and technology providers are

keen and ready to get involved in

the region. But the report found

that success and acceptance of

solar power plant construction in

the ve countries it examined –

Egypt, Algeria, Jordan, Morocco

and Tunisia – depend heavily on

the integration and participation

of local industry.

The background to the

study is the World Bank’s Clean

Technology Fund (CTF), which

is supporting the development

of solar thermal power plants in

MENA countries. An investment

programme is intended to help

nance new power plants in

the region and develop a local

CSP industry as well as attract

additional investment.

The study results indicate that

the local value added for CSP

plants in the MENA region could

average 60%. Christoph Kost,

head of the study at Fraunhofer

ISE, estimates that the effect from

local value added in the region

could total US$14.3 billion if

sustainable, long-term demand is

created, and that 60,000 to 80,000

jobs could be created in the MENA

region by 2025.

CSP’s potential for the region

Countries stand to prot from

developing production and

infrastructure if they exploit

regional advantages and dismantle

market barriers. But in the short

and medium term CSP projects

in MENA will require a portfolio

of support schemes, including

climate nance and concessional

loans, revenues from solar

electricity exports to Europe, and

national incentives such as long-

term power purchase agreements,

feed-in tariffs, or tax rebates.

In the longer term, generation

costs need to fall dramatically.

Investment costs, and therefore

manufacturing costs for main

components and systems, need

to be reduced through technical

innovation, economies of scale,

and the experience curve effect.

But MENA has technical and

industrial capabilities that are likely

to form a good basis for CSP-

related activities, found the study.

Local manufacturing of CSP

in MENA countries could also

benet from a massive scale-up

of concessional climate nancing

envisaged under the United

Nations Framework Convention

on Climate Change (UNFCCC).

In addition, CSP is central to the

high-level political agreement

between MENA and the EU

to make solar energy trade a

fundamental pillar of economic

integration between the regions.

CSP located in the MENA region

could be key to realising the EU’s

GHG emissions reduction and

energy security objectives.

A strategy for growth

National strategies for industrial

development and energy policy

should involve: clear targets for the

market diffusion of CSP; substantial

R&D efforts; the creation of strategy

funds for industrial development of

CSP industry sectors; and stronger

regional integration of policies.

More technology parks/clusters

and regional innovation platforms

are also needed, especially to

help small and medium-sized

rms overcome barriers and gain

access to the latest technological

advances, the report says.

Business models should build

on the comparative advantages

of some industrial sectors in

MENA countries and also involve

international co-operation

agreements, such as joint ventures

and licensing. A crucial rst step

will be investment in new highly

automated production of mounting

structures and white glass as well

as in adapting techniques for

coating and bending mirrors.

Market actors will need both

access to information and certainty

about the market’s development.

Feasibility studies on production

line upgrades could be key to

this. A regional trade association

might be essential. Starting local

manufacturing will also involve

comprehensive education and

training programmes. Finally,

universities should be encouraged

to teach CSP-technology courses,

particularly for engineers and other

technical graduates, the document

concludes.

MENA TIPPED

FOR CSP BOOM

MENA OFFERS THE

GREATEST GLOBAL

APPLICATION POTENTIAL

REGIONAL MARKETS

RENEWABLE

ENERGY

WORLD

RENEWABLE

ENERGY

WORLD

INTEGRATOR RANKINGS

By Ash Sharma

CHALLENGING

GERMAN RULE

New research on the global PV system integrator industry reveals that German companies continue to dominate the

market, but the number of US-based integrators is surging and the industry structure could change rapidly in the next

18 months, especially as major European markets falter amid government cuts.

US PLAYERS CHANGING STATUS QUO

Thirteen of the top 30 system integrators last year were German and,

although Germany’s dominance in newly added PV capacity is set to fall

in coming years, it appears clear that German system integrators will still

be highly prominent. They have become increasingly active abroad while

maintaining a stranglehold on their domestic market. German rms made

up 19 of the top 20 integrators in their domestic market last year and also

gained a strong foothold in other strong European solar markets such as

France, Italy and the Czech Republic.

Belectric (Formerly Beck Energy) developed more than 300 MW of

PV systems in 2010, propelling it to the top of IMS Research’s rankings

for PV system integrators. Belectric was narrowly ahead of Juwi, the

second-largest developer, and ve places ahead of 2009’s leader, Q-Cells

International, which saw close to zero MW-growth in systems developed.

Yet, despite its three-fold increase in PV systems developed and its

No.1 position in 2010, Belectric still only managed to capture a 2.4%

share of the non-residential PV market, estimated at 13.2 GW, highlighting

the highly fragmented nature of the PV Engineering Procurement

Construction (EPC) industry. IMS Research’s quarterly survey of system

integrators and EPCs revealed that the market is even more fragmented

than the PV component market, with the top 30 suppliers holding only a

22.1% share of the market, down 2% from the previous year.

US PV system integrators have risen in the rankings in 2010, IMS

Research analysis reveals. For the rst time, three large-scale system

providers from the US appeared among the 10 largest integrators. The

number of integrators in the US is also surging. Of the 400 most active

identied, nearly 30% are headquartered there, despite the country

accounting for less than 10% of 2010 global installations.

In Italy, US-based system integrators are also rapidly gaining share.

Two of these US players, SunPower and SunEdison, were the two largest

integrators in what was the world’s second-largest market in 2010.

Surprisingly, only three Italian rms appear in the top 10 for Italy in

2010, as many large US, German and Spanish suppliers rushed into this

exploding market.

In the US, the non-residential market was one of the least fragmented

last year, with the top 20 integrators holding a 66% share, albeit slightly

down on the year before. IMS Research expects this market to become

ooded by EPCs, due to massive growth predicted in 2011 and 2012, and

has already identied close to 150 active US-based system integrators,

plus many more European and Asian rms entering this promising market.

While the commercial PV integration market is very diverse, the utility-

scale market (>5 MW) is much more consolidated due to the level of

expertise required for installations of this size and the relatively fewer

plants of this size already in place or planned. Germany-based Juwi

moved to the top of IMS Research’s rankings in 2010, with a 12.1% share

of global utility-scale systems. Indeed, 2010 saw high demand for utility-

scale systems, which grew the fastest of all system types, by over 150%

from 2009. Sunpower, First Solar and SunEdison, all US providers, were

able to capitalise on this surging demand.

Certainly 2010 was an incredible year for utility-scale PV and a record

capacity from such systems was installed worldwide. Several very large

plants were completed, such as First Solar’s Sarnia project in Canada and

SunEdison’s Rovigo plant in Italy. These plants have set new standards for

the size of PV systems. They have also enabled these suppliers to become

some of the largest integrators in the world.

Author Details

Ash Sharma is Research Director of the photovoltaics group for IMS

Research.

e-mail: Ash.Sharma@imsresearch.com

This article is available on-line. To comment on it or forward it to a

colleague, visit: www.RenewableEnergyWorld.com

LARGE SCALE SOLAR SUPPLEMENT - MAY 2011

RENEWABLE

ENERGY

WORLD

RENEWABLE

ENERGY

WORLD

LARGE SCALE SOLAR SUPPLEMENT - MAY 2011

SYSTEM MONITORING

By Richard Pitkin

MODULE LEVEL

MANAGEMENT

A major market development of module optimisation technologies in recent years has brought down the cost of electronic

technologies for providing real-time monitoring data at the module level. Some products also offer additional functionality

such as theft deterrent, and module switching and isolation for re safety. What is their value to the market and what is their

justication?

EMERGING FROM THE SHADOWS

In the wake of a massive PV market expansion and a corresponding

growth in opportunity, technology entrepreneurs have been inventing

innovative value-added technologies all around the PV infrastructure

sector, from large engineering solutions to software.

It’s in the nature of the 21st century technologist to nd a technical

solution to a known problem; equally, it’s in the nature of the same

innovator to nd a problem to t a neat technology. The issue for the

customer is nding value solutions.

In the past two years, in particular, balance of systems (BoS)

technologies have emerged to add value by providing better

information and better performance for photovoltaic installations. In

an industry where billions of investment dollars are being spent on

improving conversion performance by 1%–2%, the BoS technologies

are focusing on 20%–50% improvements by ensuring PV systems are

producing close to 100% of their designed capability.

So where a balance of systems developer is selling an extra 10%,

20%, or even a 50% improvement in performance, what they are

actually saying is that the customer is not yet getting the full capability

of the investment, and this new product will help him get there.

Balance of system challenges

The challenge for all of these technologies has been to nd a

technology that adds value but that does not add signicant cost, in

a market driven by cost reduction. Furthermore, any such technology

must not erode the healthy margins of the major players that support

a 20-year-old architecture which works OK.

While feed-in tariffs stand at as much as 55 euro cents to encourage

the development of a new industry base, the project attitude has been

quite complacent. Business plan return on investment (ROI) targets

will be achieved even if some of the technology is not working. But as

governments start to rein in and reduce tariffs – as recently witnessed

in several European countries for example – achieving maximum

performance becomes far more critical and any technology that can

(at worst) guarantee and maintain target levels of performance, is

worth considering.

In the 1970s and 1980s when Europe was under severe oil price

pressure from OPEC, European automotive manufacturers were

forced to increase efciency, which led to the development of engine

efciency technologies. Core engine architecture did not change, but

the use of measurement and information at the lowest component

level by engine control units (ECUs) provided small percentage

improvements to aspects such as timing and ignition, which over time

has provided massive returns in fuel efciency.

Similarly, as PV feed-in tariffs fall and pressure is put on project

margins, it is essential that PV arrays achieve optimal performance

– and the lowest practical technology level to obtain the necessary

performance management information is the module.

An Enphase micro inverter system on tracking module Enphase

RENEWABLE

ENERGY

WORLD

RENEWABLE

ENERGY

WORLD

LARGE SCALE SOLAR SUPPLEMENT - MAY 2011

Module level Technology Development

For many years performance tuning technology has been limited to a

core function of the centralised inverter (MPPT). The only monitoring

has been either from the inverter or other centralised data loggers, so

the lowest level of management was at the string level.

So, for instance, in 2009 module optimisers such as SolarMagic,

Tigo and Solaredge appeared that use module level MPPT optimisation

dynamically to counter shading and other material inconsistencies.

The same year also heralded the ‘second coming’ of the module level

inverter/AC module – from players such as Enphase and Enecsys –

to overcome the limitations of the centralised inverter and series/

paralleled PV arrays (see box panel, right).

Last year then saw the cost of module level monitoring

and control technologies come down. Technologies such as

TwentyNinety Active Array work on the premise that performance

degradation can be random and can be caused by many external

factors that would never be detected and could even be masked by

a string monitor/inverter. If a module suffers 10%–15% degradation

from dirt or faulty materials, a string monitor would not detect

that degradation; the lower performance would be blended and

invisible to the user.

These module level technologies also provide a simple solution

to a major concern of many of the world’s reghters: the fact that

during daylight hours, anywhere downstream of a classic dumb

module – between the module and the DC isolator – is live and

therefore capable of carrying very high DC current.

By designing in sensors at the module level, some new systems

such as Tigo, TwentyNinety Active Array and Solaredge can also

provide a degree of re safety control. These systems can shut off/

isolate the individual module, either through wireless or wired

switching systems.

Performance benets quantiable?

All the new BoS technologies advertise anything up to 50%

improvement on current performance. But the higher claims come

from optimisation technologies that achieve their claims in a shaded

environment by normalising output and optimising MPPT.

But what about systems unaffected by shade, which form the

vast majority of installations? As with any electronics technology, a

solar module will experience a standard bell curve of component

and material failure. When that device is placed in harsh external

conditions, additional factors such as heat and dirt increase the

likelihood of performance degradation.

Long term studies of PV installations show that some modules

will perform optimally for long periods while others will lose as

much as 25%–30% of their capacity through environmental factors

such as heat, dirt, and snow or external factors like wiring. With

dumb modules, a 10% degraded module will then produce a

disproportionate degradation to the overall performance of the string

and could remain undetected for a long time.

While automatic module optimisation will improve the string

performance without xing the root problem, module level monitoring

solutions are designed for this classic fault scenario. Simple software

alerts identify symptoms such as a lower output than an adjacent

module, increased temperature or increased string resistance,

allowing the customer to repair or replace immediately.

Are manufacturers ready?

Key to any technology acceptance by early adopters is the value

created by the product and its price. Many major manufacturers

are taking module level technology very seriously because of the

need to demonstrate condence in their product in the face of low-

cost competition. But at the same time they are also being driven

to reduce costs and consequently this market will develop. Initially

the manufacturers will market a premium product. But, as in the

automotive industry, simple low-cost key management data will

become an essential optimisation tool for plant operators.

Author Details

Richard Pitkin is Managing Director of TwentyNinety Ltd

e-mail: andy.barber@twentyninety.com

This article is available on-line. To comment on it or forward it to a

colleague, visit: www.RenewableEnergyWorld.com

MICROINVERTER MOVE ON MODULE MANAGEMENT

Unlike a central, or string inverter, a microinverter converts DC

power from a single module to AC. When connected to a central

inverter, modules are typically connected in series; when they have

micro-inverters, the modules are connected in parallel.

Advances in electronics made them commercially viable, enabling

manufacturers to address some of the challenges associated with

standard central inverters. Manufacturers are also offering smart

monitoring as part of their package to customers. The changes in

the size and sophistication of these devices, and consequently the

overall improvements in solar system performance, helped bring

about the convergence of energy and information technologies.

Previously, Raghu Belur, Enphase’s marketing VP, explained to REW

how the rm came to develop its micro-inverter. ‘All entrepreneurs

go looking for a problem; the harder the problem, the better it is.

Our CTO and co-founder, Martin Fornage, installed a solar system

on his property and during that time recognised the limitations

of a traditional inverter solution.’ Continuing, he said: ‘Other

people had worked on micros before but had been unable to

make the technology commercially viable. Our approach, with its

digital design and development of custom semiconductors made

the micro-inverter commercially viable and attractive,’ adding,

‘We were able to address the issues of efciency, reliability and

cost for the rst time. We didn’t think of it simply as a piece of

hardware, but instead as a system, which means embedding

computing technology and monitoring for operations and

maintenance purposes. And a lot of that comes from the founders’

backgrounds. I came from Cisco Systems, which has a very system

level approach to all its activities.’

RENEWABLE

ENERGY

WORLD

RENEWABLE

ENERGY

WORLD

LARGE SCALE SOLAR SUPPLEMENT - MAY 2011

MODULE RELIABILITY

By Eric Fitz

RELIABILITY OR

DURABILITY?

Even low rates of failure can result in signicant commericial losses for the owners and operators of solar power plants.

However, despite the signicance of the issue, there is little empirical data available and prediction tools remain immature.

ADDRESSING THE BOTTOM LINE IMPACT

The PV industry is increasingly focused on module reliability. However,

misuse of the terms ‘reliability’ and ‘durability’, immature long-term

reliability prediction tools, and a general lack of empirical data make

it difcult for the industry to characterise the nancial and operational

risks associated with photovoltaic power generation installations.

While PV module qualication tests have progressed tremendously

over recent years, they cannot by themselves fully predict lifetime

reliability. Failure rates, even small ones, can drive lost revenue

for investors, developers and plant operators. Given these issues,

investors, developers and manufacturers clearly need to actively

consider module reliability in their risk management portfolios and

there are a number of factors concerning PV reliability that shed light

on this situation.

Reliability versus durability

Reliability is a measure of a system’s or component’s probability of

failure over time where failure is dened as a discrete (and most often

sudden) event that has immediate and typically catastrophic impact

on performance. A highly reliable PV module therefore has a low

probability of such failure over its lifespan.

Durability, however, is a measure of how well a system or

component resists performance degradation over time. Unlike the

sudden decline associated with reliability, durability is characterised

by a continuous gradual loss of performance. In today’s market, PV

modules are considered to be durable if they maintain a typical

warranty offering of at least 80% of their original performance

specication after 25 years of operations.

In summary, reliability is a sudden total loss of performance;

durability is a gradual performance decline.

PV module reliability issues

At rst glance, a PV module seems like a pretty simple product:

a rectangular panel that produces electricity when exposed to

sunlight. However, a module is comprised of dozens of materials

and components, including the back contact sheet, semiconductor,

transparent conductors, encapsulates/sealants, cell-interconnects/

solder joints, glass, and bypass diodes.

Each module component, sub-component and/or underlying

material has various and sometimes independent failure mechanisms

that could ultimately lead to poor module reliability.

There are also a number of environmental stressors that can cause

problems or exacerbate manufacturing defects and thus accelerate

failures. These stressors include, for example, rapid thermal cycling

due to sun and passing clouds; extreme temperatures in winter and

summer; mechanical loading caused by wind and snow; and, moisture

inltration due to high humidity.

Exacerbated by environmental stresses, which can accelerate failures,

module reliability presents signicant performance risk Yongsun Solar

RENEWABLE

ENERGY

WORLD

RENEWABLE

ENERGY

WORLD

Co-Branded Marketing & Sales Tools

Sales Leads

Sales & Technical Training

Dealer Financing

And Much More

Superior Authorized

Dealer Program

Which Would You Rather Install?

Ordinary Solar

Power Systems

888.395.2248 | WestinghouseSolar.com

Become a Dealer Today

Grow your business with the

power of Westinghouse Solar

See Us

InterSolar Munich

June 2011

Booth

A3-220

LARGE SCALE SOLAR SUPPLEMENT - MAY 2011

These conditions can result in thermal expansion cracks, material

warping and discoloration, conductor corrosion and contamination.

The National Renewable Energy Laboratory (NREL) has pointed out

that reliability engineering is a deep and active eld. For example,

Advanced Product Quality Planning, Design Failure Modes Effects

and Analysis, Fault Tree Analysis, Design for Manufacturability, and

Design Review Based on Failure Mode are only a few of the methods

used by module manufactures to ensure reliable products. And,

Failure rate (%)

97-05 05-07 07-09

IEC test type (thin-film)

Initial dry highpot

Initial wet resistance

Thermal cycling (200 cycles)

Thermal cycling (50 cycles)

Humididty freeze (10 cycles)

Damp test

Outdoor exposure

Termination

Hail impact

Static load

Diode

Hotspot

UV test

Figure 1. Failure rate comparison of thin-lm modules for 1997–2005,

2005–2007, and 2007–2009 from IEC 61646 TÜV Rheinland

97-05 05-07 07-09

Failure rate (%)

IEC test type (c-Si)

Initial dry highpot

Initial wet resistance

Thermal cycling (200 cycles)

Thermal cycling (50 cycles)

Humididty freeze (10 cycles)

Damp test

Outdoor exposure

Termination

Hail impact

Static load

Diode

Hotspot

UV test

Figure 2. Failure rate comparison of crystalline silicon modules for 1997–

2005, 2005–2007 and 2007–2009 from IEC 61215 TÜV Rheinland

For more info, enter 61 at rew.hotims.com

RENEWABLE

ENERGY

WORLD

RENEWABLE

ENERGY

WORLD

LARGE SCALE SOLAR SUPPLEMENT - MAY 2011

while these are useful tools for designing and manufacturing robust

PV modules, they do not accurately predict the long term module

reliability performance.

Predicting module reliability

Lifetime reliability prediction leverages expertise from multiple elds

and requires complex experimental setups. Accelerated life testing

(ALT), PV module qualication testing, and historical eld data all play

an important role in developing accurate predictions.

ALT describes a broad group of qualitative and quantitative

methods used to predict the probability of failure and/or the potential

failure mechanisms of a given product. Since it is too costly and

impractical to collect eld data for 25 years, accelerated test methods

are often used to predict module performance. These tests rapidly

cycle temperatures, humidity, mechanical loads, light intensity, and

so forth, in order to simulate environmental stress experienced by a

module over its operational lifetime.

TAKING ALL THESE PIECES OF

INFORMATION AND BUILDING AN

ACCURATE MODEL IS A PROBLEM

PV module qualication tests such as International Electrochemical

Commission’s (IEC) 61215 for crystalline-silicon (c-Si) modules or IEC

61646 for thin-lm modules are two standards that rely heavily on

ALT, for example. Figures 1 and 2, on page 11, show failure rate

data against IEC tests from several generations of thin-lm and c-Si

photovoltaic modules.

While it is clear what conditions were present when a failure

occurred, it is often difcult to discern the root-cause component,

sub-component and/or material that ultimately led to the module

failure. Many industry experts are also quick to point out that the

qualication tests (and ALT in general) are not accurate predictors of

long-term reliability on their own. They argue that such tests are in

effect only useful for identifying defects that are likely to arise in the

rst few years of eld operation.

In addition to ALT and required qualication tests, the industry

also relies on historical eld data as a basis for prediction. However,

other than research completed at national labs, there is a limited

body of publicly available data on module reliability. For instance,

BP Solar is one of the few manufacturers which have willingly shared

performance data. From 1994–2002, BP had around 2 million of its

Solarex c-Si modules in the eld. Over this period a 0.13% module

failure rate was observed. More recently, using a combination of

historical data from Tucson Electric Power’s eet of some 5 MW of

Schott Solar c-Si modules and computer modelling, Sandia National

Labs has forecasted a module replacement rate of 0.05% per year.

Nonetheless, taking all of these pieces of information (ALT,

qualications test results and historical data) and building an accurate

prediction model for new products is a difcult problem. Due to

the complexity of lifetime prediction, the US DOE’s Solar Energy

Technologies Program has held industry workshops four out of the

last ve years to discuss this issue. Even with the recent effort and

progress, there is still a lot of work to be done.

The big picture

As shown in gure 3, above left, in a recent research paper the Electric

Power Research Institute (EPRI) claims that the lifecycle operations

and maintenance (O&M) cost due to poor inverter reliability dwarfs

that of PV modules, with a gure of 50% for the inverter against the

5% gure given for the module. That analysis suggests that only

US$2-3/kW-year is in fact spent on module O&M.

Analysis from EPRI further notes that overall module failure is

responsible for less than 1% of energy losses from PV systems, as

shown in Figure 4, above right. However, there are three items to

note about this particular EPRI data set. Firstly it comprises almost

all at-plate, c-Si modules, secondly SunPower is an established

company and an industry leader in quality, and SunEdison is also

a well established developer in the PV industry. Unfortunately, the

limited data for thin-lm systems is not as rosy. A Conergy developer

aparently has noted that, ‘First Solar accounts for 2% breakage,

though [Conergy is] seeing far less than 1% on most of [their] projects

over the rst year.’

If the best-in-class thin-lm manufacturer sees failure rates around

1%–2%, failure rates could exceed 2% for new market entrants. As

the industry expands and new technologies are introduced, the

expectation is that failure rates could climb even higher.

AC subsystems

Inverters

DC subsystems

External

Energy loss

# of events

Communications

Unknown

Support structures

Modules

No Failure (PM)

10 20 30 40 50 60 70

Relative share (%)

Figure 4. Relative frequency of PV system component failure and outage

impact, SunEdison, January 2008–September 2009 EPRI.

Inverters

Site work and miscellaneous

Communications/DAS/SCADA

Tracking related

Wiring

Module

Array structure (non-tracking related)

0 102030405060

Lifecycle maintenanace costs (% of total)

Figure 3. Total lifecycle PV plant maintenance costs for Sunpower’s

managed eet EPRI

MODULE RELIABILITY

RENEWABLE

ENERGY

WORLD

RENEWABLE

ENERGY

WORLD

Eliminate that cost with technology

For more information, visit www.raycapsurgeprotection.com

What does lightning & overvoltage damage cost you?

Raycap’s state-of-the-art Strikesorb based Surge Protective Devices

reduce repair and replacement expenses, eliminate downtime and

revenue losses resulting from lightning and overvoltage surge events.

Only maintenance-free Strikesorb modules can endure multiple

lightning strikes and transient overvoltages to efficiently protect

photovoltaic installations.

Generate Power Continuously

Generate Revenue Continuously

Superior Surge Protection Technology





standards

!!!"

!#!$"%"&'#""!

junction boxes

LARGE SCALE SOLAR SUPPLEMENT - MAY 2011

On the residential scale, module reliability is even more important.

For a small array of around 4 kW, a single module can represent 5%

of the total system output. And because these small-scale systems

miss out on the benets from economies of scale, capital costs are

high and they have longer payback periods. Without the benet of

full-time O&M staff (unless the homeowner has a third party service

agreement) an undetected module loss can have major impact on

nancial returns.

Module warranties

In the early 1990s, 10-year warranties were typical. Today, almost all

manufacturers offer 20–25 year warranties. But a 25-year warranty

doesn’t mean modules are necessarily protected. A number of issues

must then be considered.

Will module suppliers be around in 15 years if and when problems

arise? Do they fund an escrow account to ensure that, even if they

have disappeared from the market, customers still will be protected?

Do they rely only on IEC qualication tests to make claims about long-

term durability? If they have only been around for ve years, how can

they claim that their modules last for 25 years?

There are encouraging signs, for instance the increase in length

of warranties is promising, but an investor or developer must carefully

review the company providing such a guarantee to ensure that it

provides the long-term risk protection required.

Countering operational risks

Module reliability and durability are separate issues that a potential

investor must consider independently. PV modules can fail in many

ways, but the risk seems relatively low based upon module reliability

studies. However, that said, there is little public data available on

actual eld results with which to verify the studies.

Furthermore, a project with narrow margins could be impacted

by even very small losses in generation or increased O&M costs.

Even when backed by a warranty, failure rates drive lost revenue

for investors, developers and plant operators. As such, a potential

investor should carefully consider a module manufacturer’s track

record, qualication tests, reliability forecasts and warranty coverage

before investing in a project.

Author Details

Eric Fitz is a managing consultant in Navigant Consulting’s Energy

Practice.

e-mail: eric.tz@navigantconsulting.com

This article is available on-line. To comment on it or forward it to a

colleague, visit: www.RenewableEnergyWorld.com

For more info, enter 62 at rew.hotims.com

RENEWABLE

ENERGY

WORLD

RENEWABLE

ENERGY

WORLD

LARGE SCALE SOLAR SUPPLEMENT - MAY 2011

INVERTER COST STRATEGIES

By Andy Extance

INVERTERS IN

COST CONFLICT

Having matured to a level where PV inverter manufacturers are pitting clearly differentiated strategies against each other,

PV inverter manufacturers still want to lower their costs, whether it be by adopting industry-wide strategies or through

more individual efforts. However, Chinese government action could also open up divisions in the near future.

MANUFACTURERS DRAW BATTLE LINES

Starting from a gentle trickle in the 1980s, over the past 10 years the

amount of electricity generated by PV power plants and owing into

power grids around the world has multiplied to a comparative torrent.

Whether that grows to a full-spate ood depends in large part on

countries putting in sufcient effort to develop affordable, sustainable,

solar power. Today, programmes like the US government’s ‘Sunshot’

initiative to reduce installation costs below $1/W point the way forward.

Feed-in tariffs providing direct rewards for each watt generated across

the world have contributed substantial incentives rewarding installations

of PV power generation, and still do so. Consequently, the PV industry

has undertaken a signicant ramp-up of its manufacturing capacity.

For those making inverters that convert the direct current owing out

of PV panels into alternating current that can enter national power grids,

the resulting ramp up has been necessary, says Yole Développement

market analyst Brice Le Gouic. ‘Before you had companies from the

industrial or rail traction business,’ he told Renewable Energy World.

‘In between, sometimes they manufactured inverters for PV, but the

processes were not clearly dened.’ Now that the PV inverter market has

become a clear driver of growth, manufacturers want specic strategies

to ensure they can take full advantage of it. From this beginning, three

distinct classes of company have evolved to inhabit the inverter industry,

seeking the best chance of success given their particular strengths.

The 1 MW-range inverters used in industry were obvious candidates

for transferring to the highest-output segment of the PV industry. Today,

however, there are two other important segments to consider. The

residential segment with installations below 10 kW, and the commercial/

industrial segment of between 10 kW and 500 kW, with solar farms

typically above this range. Residential inverters can be compared to

consumer electronics products with their high volume/low margin, while

large inverters are low volume/high margin products.

Inverters deployed in these different segments can be separated

into two types used above and below 100 kW, Le Gouic explained.

‘In the industrial segment below 100 kW people will use inverters that

are somewhat like the small ones used in residential applications,’ he

said. These will only allow one or two ‘strings’ of PV modules connected

in series, meaning that several inverters must be used. A key advantage

of this approach is that as inverter technology progresses the power

rating of this class of inverters increases, meaning that fewer are needed.

‘Now the industry is working towards 15 kW inverters from around 8 kW

a few years ago so, for the same installation size, you can have less

inverters that are still single strings,’ said Le Gouic. Installations above

100 kW use larger, more custom-made, inverters, he added.

While two of the three inverter producer classes address all these

market segments, the third can be dened as those companies which

narrow their focus. One example is Spain-headquartered inverter

Low cost and clean: SMA Solar Technology’s fully automated inverter

production provides it with an economical manufacturing infrastructure, while

also being carbon neutral SMA Solar Technology AG

RENEWABLE

ENERGY

WORLD

RENEWABLE

ENERGY

WORLD

Renewable Energy World - magazine - 5/6-2011

Подождите немного. Документ загружается.