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Photovoltaic for homes.

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N° 20-10 
Sol-ion, Europe’s largest PV energy conversion and storage project, moves 
into field trial phase   
• Close collaboration between industrial partners Saft, Voltwerk and Tenesol has 
resulted in the successful development of a prototype integrated energy kit suitable 
for production on an industrial scale  
• EU-backed project is now moving into field trial phase with 75 Sol-ion energy kits 
being deployed in France and Germany from mid-2010 onwards 
Munich, June 10, 2010 – Saft, Voltwerk and Tenesol, industrial partners in the EU-backed Sol-ion 
project, have successfully completed the development phase by creating an integrated energy 
conversion and storage kit, capable of production on an industrial scale, for decentralized on-grid, 
residential solar photovoltaic (PV) systems. The project, which commenced in August 2008, is now 
moving into its test and evaluation phase. This involves the deployment of 75 Sol-ion energy kits for 
field trials across France and Germany. 
The Sol-ion trials will see Li-ion (lithium-ion) batteries used in PV systems on the largest scale ever 
tested in Europe. The trials will be used to assess the performance of the technology, its economic 
viability, the added value of energy storage in an on-grid system and the benefits to stakeholders. 
‘The key to the success of the Sol-ion project is the way that all the individual partners, both from 
industry and from the research institutes, have come together in close collaboration to function as a 
seamless team. So rather than each partner providing a separate element – batteries, energy 
conversion and system management – and then bringing them together, we have focused right from 
the very start on the delivery of a comprehensive, fully-integrated, optimized solution’ says Michael 
Lippert, Marketing Manager of Saft’s Energy Storage activities. ‘We are very excited to be moving into 
the field trial phase as this will provide invaluable practical experience and feedback that will help 
refine our approach as we move a step closer towards making PV energy storage kits commercially 
Currently, the majority of grid-connected PV systems do not include energy storage and the electricity 
produced is fed into the grid directly, in real time. The advantage of the Sol-ion energy conversion and 
storage concept is that solar energy can be ‘time-shifted’ to periods of peak demand or when there is 
no sun, allowing self-consumption or grid support. The field trials will demonstrate the benefits to the 
environment and to stakeholders of storing PV energy. One key benefit will be to reduce the impact of 
intermittent injection to power grids, thus allowing a higher penetration of PV energy in the electricity 
Sol-ion kit 
The Sol-ion kit has been developed to accommodate PV energy production of 5 kWp (peak) with a 
battery rated from 5 to 15 kWh and a nominal voltage of 170 V to 350 V. Li-ion is the only technology 
that meets the project’s need for 20-year battery life in demanding environmental conditions. 
The energy conversion and system management  systems are designed to handle four system 
functions: multidirectional energy flows; self-consumption; grid support; back-up. They are also 
intended to handle requirements for demand side management such as control over storage and 
loads using smart metering, and integration within future smart grids that will need to handle demand 
response and dynamic pricing. The Sol-ion battery is based on Saft’s high energy Li-ion modules, with a nominal voltage of 48 V and 
2.2 kWh capacity. These compact, maintenance-free modules feature an advanced and robust 
industrial design, and they can easily be connected in series or parallel to create the desired voltage 
and capacity for each installation. Saft’s Li-ion  technology has already proven an impressive 97% 
energy efficiency in a recent 2 years field demonstration in residential PV systems in Guadeloupe. 
Saft’s technology partners in the Sol-ion project  are leading PV systems providers and integrators: 
Germany’s Voltwerk has installed over 70,000 PV systems; France’s Tenesol supplies integrated PV 
systems and also manufactures solar panels. E-ON, the German utility, three German research 
institutes (ISEA, Fraunhofer IWES and ZSW) and INES-CEA, the French research institute, are also 
associated with this project. 
Sol-ion has been recognized by the EU/Eureka/Eurogia programme and has the support of the 
French Ministry of Economy, Finance and Employment and the German Ministry of Environment.  
About Saft 
Saft (Euronext: Saft) is a world specialist in the  design and manufacture of high-tech batteries for 
industry. Saft batteries are used in high performance  applications, such as industrial infrastructure 
and processes, transportation, space and defence. Saft is the world’s leading manufacturer of nickel 
batteries for industrial applications and of primary lithium batteries for a wide range of end markets. 
The group is also the European leader for specialised advanced technologies for the defence and 
space industries and world leader in lithium-ion satellite batteries. Saft is also delivering its lithium-ion 
technology to the emerging applications of clean vehicles and renewable energy storage. With 
approximately 4,000 employees worldwide, Saft is present in 18 countries. Its 15 manufacturing sites 
and extensive sales network enable the group to serve its customers worldwide. Saft is listed in the 
SBF 120 index on the Paris Stock Market. 
For more information, visit Saft at
About Voltwerk electronics GmbH 
Voltwerk electronics GmbH is an internationally successful manufacturer of string and central 
inverters, tracking systems and facility monitoring systems. All its products are developed and 
manufactured in Germany. Voltwerk‘s award-winning products have been installed worldwide in 
systems with a total of more than 500 MW of generating capacity. Voltwerk is a provider of innovative 
solutions and pioneering methods for highly efficient photovoltaic systems.  Voltwerk’s success is 
based on precise knowledge of the markets and intensive collaboration with customers and 
engineering teams across the world. Voltwerk is  represented in Bad Vilbel and Hamburg and has 
sales and service support in all the major European markets. Voltwerk electronics GmbH currently 
has nearly 100 employees. For more information visit Voltwerk at
About Tenesol 
A rapidly expanding global player in the field of solar energy (with a turnover of €249 million in 2009, 
+29%), Tenesol works on behalf of businesses, local authorities and private individuals. For more 
than 26 years, Tenesol has been engineering, designing, manufacturing, installing and managing 
solar energy systems including production  and consumption of supplied systems  (Off-grid sites, 
general grid supply via direct connection, solar water heating) for its customers around the globe. A 
benchmark player in its sector, Tenesol currently  has a staff of over 1,000 employees across 20 
subsidiaries including 2 production facilities. For more information visit Tenesol at
Press contacts 
Jill Ledger, Saft Communications Director, Tel: + 33 1 49 93 17 77  
Marie-Christine Guihéneuf, Saft IBG Communication Manager, Tel: + 33 1 49 93 17 16 
e-mail :
Andrew Bartlett, Six Degrees, Tel: + 44 (0) 1628 480280 
e-mail: andrew.bartlett@sixdegreespr.comBACKGROUND INFORMATION
The role of each partner
Saft is responsible for the design and manufacture of the energy storage system. The battery is based 
on Li-ion battery modules connected in series to obtain the energy and voltage required by the 
application. This concept provides a high level of modularity offering a wide energy window without 
additional development. Each module includes an  electronic board for data acquisition (voltage, 
temperature, ..) and cell balancing in order to optimise the battery life time and to allow 
charge/discharge control, state of charge measurement, etc. 
This electronic board is connected to the system management function that controls the battery. The 
interfaces have been developed in cooperation with Tenesol and Voltwerk. 
Saft is delivering the batteries both to Voltwerk and Tenesol. These two PV system integrators will 
produce the other components and will assembly the  Sol-ion kits (battery + inverter + system 
Voltwerk and Tenesol 
With their extensive knowledge in the production  of inverters, Voltwerk and Tenesol have specified 
and developed the inverter and the energy management system to meet the customers’ 
requirements. The system design allows the inverter to either feed the electrical power into the public 
grid or store it in the battery for later use. 
Voltwerk is producing and installing 25 systems  in Germany. Tenesol will  produce and  install 50 
systems in various demonstration sites in mainland France and overseas departments. Finally, field 
test demonstration supervision  and data acquisition will be carried out for system monitoring and 
future system improvements 
E-on is providing access to its network in Germany and is contributing to the development of the 
system’s interface with the network. 
Research institutes 
These organisations are responsible for modelling the system and its impact on the network, and for 
the analysis and utilisation of the test results. 
Organisations involved in the project 
Partner Core business 
Saft – Project coordinator Batteries 
Voltwerk Renewable energy products integrator 
Tenesol PV systems integrator 
E-ON Utility 
Fraunhofer IWES Research Institute 
ZSW Research Institute 
ISEA Research Institute 
INES-CEA Research Institute 
All the partners have confirmed their strong interest in the development of grid connected PV 
systems, associated with a storage function and recognize that this concept offers new business and 
market perspectives. The role of energy storage in renewable energy systems
Example of residential PV system with energy storage 
PV installations with a permanent connection to the electricity grid are categorised as ‘on-grid’ 
applications. This is the most popular type of  solar PV system for homes and businesses in the 
developed world. PV can be installed on top of a roof or integrated into the roofs and facades of 
houses, offices and public buildings. An inverter is used to convert the DC power produced to AC 
power for running normal electrical equipment. 
Private houses are a major growth area for roof systems as well as for Building Integrated PV (BIPV). 
A typical 5 kWp panel in southern Germany delivers approximately 5,000 kWh/year – sufficient to 
supply nearly all the annual electricity needs of an energy conscious household. 
Connection to the local electricity network allows  any excess power produced to be sold at peak 
hours to the utility. Electricity is then imported from the network outside daylight hours. 
The role of energy storage in an on-grid application is to store excess PV energy until it is needed. 
Effectively, energy storage will ‘time-shift’ PV energy produced during the day, peaking at noon, to 
make it available on demand. This will both maximise local consumption and enhance the efficiency 
of the PV system. Surplus energy can also be fed back into the grid, for which the owner of the PV 
system would be remunerated at a higher tariff. 
Energy storage will also increase security of supply while making individual consumers less 
dependant on the grid. It will also help to boost the development of energy self-sufficient houses and 
buildings and contribute to the continuous growth of PV as part of the global energy mix. 
The main benefit of on-grid energy storage for utilities is that it will reduce the peak load on their grid 
while at the same time making PV a source of predictable, dispatchable power that they can call on 
when needed. Reduced grid losses, i.e. the energy lost by transporting power from a centralised 
generator to the point of use, will result in some energy savings. Savings due to reduced consumption 
in PV powered households are anticipated to be 10 to 20 per cent. Rationale for on-grid energy storage
The change in emphasis for on-grid PV production has created an increasingly sound rationale for 
energy storage that maximises local consumption by time-shifting PV power from the peak production 
to the evening, when it is most needed. Furthermore, the more of its own-produced power that the 
household uses, then the more independent it becomes from the grid and the more secure its supply. 
Energy storage will also enhance the efficiency of PV production and will play a role in improving 
power quality and power ability. 
Any surplus energy can also be injected into the grid for which the household will be paid at a high 
The utility will also benefit from its consumers having energy storage since this will reduce peak loads 
on the grid. It will also enable it to make use of PV as a predictable, dispatchable, form of power. The 
utility will be able to call on this stored energy at  periods of high demand. Yet at periods of peak 
production and low demand, the utility will not have to accept the excess power, and this will avoid 
any potential overloads on the grid. 
Socio-economic impacts 
Energy storage could offer a number of socio-economic benefits. Mainly, it will help to stimulate the 
continuous growth of PV as part of the overall energy mix. It will also help to reduce grid losses and 
encourage reduced consumption in PV households.

About pfiddle

Fiddle teacher - mostly Irish trad. Fiddle, mandolin and concertina. Eco-warrior, won E.U. Green Flower Award for Eco Accommodation. Also Irish (Gold) GHA. Green Hospitality Award. Mad keen on self-build - especially straw-bale and cob. 55 with a full head of (slightly) graying hair. No tattoos or piercings. Fond of animals - but legally so. Fond of food - I eat nothing else. Vegetarian by choice, Irish by the grace of birth, Munster by force of (rugby) arms.

2 responses »


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