Last week I attended Intersolar & EES Europe, a huge three day trade exhibition on all things related to solar power and electrical energy storage. Many of the latest solar and storage products were on show at the fair as well as a preview of what is coming in the next few years. I have selected some of my highlights that I think will be of most interest to Carbon Coop members.
Batteries, batteries, batteries!
All the talk this year was about a coming ‘battery revolution’ with large manufacturers like LG and SMA and start-ups like Sonnen showing their latest consumer battery and battery system prototypes and products. Whether or not this revolution is actually here, many solar manufacturers and others are seeing storage as a way to maintain sales in a stagnant European renewables market. Many of the latest developments are also around lithium based battery systems which have many advantages over the older lead acid batteries in a European residential context (smaller size, lower weight, lower maintenance, and longer service lives).
Battery storage systems are much more complex than solar PV on its own and present a bewildering range of options and specifications to consumers. There are broadly two ways of categorising the systems approaches that are emerging in the residential area. One is ‘integrated’ versus ‘modular’ systems. Modular systems involve separating the battery and the charger and inverter (which can also be from different manufacturers). Show winners like LG Chem’s new RESU high-voltage batteries and SMA’s compatible Sunny Boy Charger (also compatible with the vaunted Tesla Powerwall) fall into this category and can be combined to form a complete system which can be added onto an existing solar PV system. For those looking for a completely new solar and storage system it makes more sense to use a single hybrid inverter for the solar PV and batteries such as those from SolarEdge and Fronius which can be combined with either the Tesla or LG batteries.
Whilst such systems are more flexible they may involve higher installation and integration costs due to the use of disparate components. There are also upcoming ‘integrated’ systems like the Enphase Storage System in the US, Sonnen eco and SolarWatt MyReserve in Germany, or Powervault in the UK, which contain both the batteries and charger/inverter in a single unit. These are mainly aimed at retrofit onto existing solar PV systems and usually are coupled into the house’s AC distribution. Compared to modular systems, these benefit from potentially lower installation/no integration costs (they are AC only and dont require any DC coupling which most electricians dont have experience with) and more compact sizes at the expense of being less flexible.
It is notable that many of the new generation of battery systems come from start-ups with small install bases which has an impact on the bankability of such systems. Customers looking to purchase a battery system should carefully weigh the risks involved in using such new technologies and look carefully at the conditions of the warranties offered. Carbon Coop members are welcome to seek advice from us if they are considering purchasing a battery system and we will soon be producing some guidance on this as well.
On the purely solar PV side there was a lot of buzz around new bifacial solar modules from SolarWorld, LG, and Panasonic. Bifacial modules can generate power from radiation falling on both sides of the module giving a boost of up to 30% of the power output of a module.
As an example application, a bifacial module standing vertically facing west/east will generate more power earlier/later in the day but less overall than a more conventional siting. But this is when power is actually needed in UK homes, so despite costing more than a conventional module they can make more sense in a world of low feed in tariffs and increased self-consumption and maybe more cost effective than installing a battery to store energy generated in the middle of the day. They also offer more possibilities for creatively integrating PV in buildings where light can be received from both sides of a surface.
Smart Renewable Energy Forum
Running in parallel with the exhibition was a series of talks and discussions on the theme of ‘Smart Renewable Energy’ of great relevance to Carbon Coop’s Green Shift project and other work. One of the most positive messages (from the Director of the Fraunhofer ISE no less) was that electricity grids can be easily upgraded now to accomodate 80% or more renewables which is something Germany has achieved in only 10 years by adding intelligence into their grid infrastructure. Other interesting projects presented were:
Tiko is an aggregator in Switzerland involving 20000 homes which creates demand flexibility by remotely controlling heat sources such as electric heaters and heat pumps. As well as enrolling customers in demand side response programmes they are also granted full remote control of the devices themselves through an app and website. This requires a remote switch to be installed in series with the heating appliances and a base station for communication with the aggregator. Customers benefit financially through bill savings as well as being proactively involved in the companies contribution to achieving renewable energy targets.
This is a similar project to Tiko conceived as a ‘virtual power plant’ with large trials involving heat pumps, chp, and solar plus storage in Germany. It is facilitated by a low-cost control system.
IRENE and IREN2
Siemens has been involved in two projects where a micro-grid is built into the existing electricity infrastructure, maintaining its connection to the existing grid, but with the ability to ‘island’ itself and supply all its own energy using a variety of generators and storage facilities. This comes with all the requirements associated with the larger grid including the ability to stabilise and balance the grid and be able to restart it in the event of a black out. One thing that was emphasised was that battery storage is key in this context for active network management. Another interesting observation was that smart meters on their own were not sufficient to manage such a grid but additional sensors on the customer side as well as across the distribution network were needed to gain a complete picture of what is going on.
This is a French ‘digital aggregator’ which uses M2M communication to manage a network of generation and storage assets across 2800 nodes.
I would like to acknowledge the support of Dalarna University, Vela Solaris, and the International Solar Energy Society (ISES) who helped to organise and pay for my attendance.