How Battery Storage Could Delay PV Development

A simple survey of the most used words in the PV sector these days could surprise anyone coming back from a two years’ trip in Amazonia: the growth is back (with two digits please), Perovskites PV is the new Graal (I will come back on this subject soon) and battery storage seems the ultimate step of PV development.

Batteries? Has PV reached such a competitiveness stage that we need urgently storage? Storage, well… the arguments for using storage are numerous and from a technical point of view rather sound. Let’s forget about disconnecting from the grid: in developing countries, this looks more like a phantasm against big-government and utilities-villains than a reliable business model for the future. So let’s check sound arguments one by one.

First, storage can increase the self-consumption ratio for a prosumer. This is true and while the business model for such use of batteries is limited to a few segments in a few countries for the time being, it could increase in the coming years. Will it really develop like this or will other ways be considered as less risky and/or more effective or cost-competitive to increase self-consumption? Heat-pumps, direct sanitary water heaters (a very convenient solution actually) or simply reducing PV system size could bring similar advantages as well.

Second, storage can ease the integration of PV into the distribution grid by limiting the injection of excess PV electricity and therefore reduce the costs of grid extension and reinforcements (and consequently ensure a faster deployment of PV). However, even if it is true, other technical solutions, including moderate curtailment appear in most cases less costly (www.pvgrid.eu), even from a prosumer’s point of view. Moreover, storage used inside the distribution grid could appear more effective from a system point of view, combined with other technical solutions.

Gaëtan Masson, Director

 

Third, storage appears necessary to mitigate the intermittency of PV production. This argument is right and wrong at the same time: PV can be considered as intermittent at the production point but not at country level (except in countries with 5 installations…) where the geographical smoothing transforms intermittency into predictable variability. EPIA’s Connecting the Sun report proved it based on real data while the German SMA’s aggregated curve is obvious: PV is not intermittent but variable and quite predictable.

Fourth, the question of generation adequacy remains vivid in the political debate. The popular wisdom understands that PV and Wind will not be able to cover every day the electricity demand and translates this into a need for storage. This is indeed the case, but not as it is traditionally understood. It would be too complex here to detail how systems with 100% renewables could cover electricity demand with storage and demand response. However the question is rather HOW storage could play a role. Through decentralized storage? Through mobile storage ? And which technology? It seems premature to answer such question before being simply able to define which electricity mix will be targeted. Therefore it is premature to opt for one or another storage technology.

Finally, the question of the ramp-up and ramp-down rates is more complex: by modifying the load curve into a residual load curve, PV, Wind (and other non-dispatchable renewables) can increase the speed at which the grid operator has to adjust production and consumption. EPIA (op.cit.) showed that 100 GW of storage capacity would be optimal to manage 15% PV and 30% Wind at European level. We are quite far from these levels (and the new 2030 targets in Europe are significantly lower than that) and 50 GW of pump-hydro storage is already operational in Europe. At country level, the case could be more complex with inflexible electricity mixes (France for instance) and limited interconnections with neighboring countries (several Asian countries, Korea for instance).

So do we need battery storage ? And do we need it now ?

The constraints associated to PV development in countries where PV used to develop until now can be mitigated using various technologies. The investment in battery storage could become rapidly counter productive while the PV industry still requires R&D&D support and the PV market some incentives. Let’s make the right budget choices with the available money, especially in Europe.

In developed countries again, an additional question lies in the location of the battery storage: the expected emergence of electric vehicles (EV) could provide access to storage for millions for prosumers, providing the fact that automotive manufacturers are giving access to their batteries within smart homes (or smart companies) systems.

In developing countries, the question can be different, and battery storage could be seen as an alternative option to reinforce weaker grids. For the 2 billion people on earth without access to electricity, battery storage will often be the only solution to electrification. In that respect Bangladesh has proven with pico-PV systems that such deployment is both feasible and financially sound.

Storage and storage

Storage is used every day in many countries, through pump-hydro stations. It is rather funny to consider that several pump-hydro stations in Belgium or France where built initially to mitigate the inflexibility of nuclear power plants, and the risk of intermittency (when stopping in emergency GW-scale nuclear plants). Such technology represents, under the right regulatory framework, a cheap, mature and centralized way to hedge against variability risks. Other promising technologies could become competitive in the coming years, such as super- and ultra-capacitors, that could challenge chemical batteries.

Playing with fire

Storage will be a necessary step towards a 100% RES electricity (and energy) system. There is little doubt about that. The question lies rather in the precise moment when PV will absolutely need storage to develop. Today, the hype towards batteries shouldn’t eclipse the other challenges that PV needs to fulfill in order to develop steadily on a global scale. Despite more than 40 GW installed this year, the PV market remains under the threat of inadequate regulations, policy orientations in a limited number of countries and the opposition from conventional utilities in many countries. In fact, the latter would be too happy to require from every PV installation a battery system…

PV is about to change the way the world is powered. At the consumer freedom to switch the light on and off, PV is adding a new degree of freedom. Decentralized batteries will add a second degree of freedom to the system, but is it the right moment?