The future of photovoltaics relies on self-consumption and to develop it, especially at residential level, new materials are needed for panels and batteries. As for self-consumption based on batteries, I’d rather call them hybrid installations, these are isolated solar installations that do not necessarily need a power network to operate, but instead they use this network as a support or they can work either in parallel to the network or isolated thereof.
The operation scheme of these systems is varied, although there is a trend towards facilities that operate in parallel with the network so that when production exceeds consumption, instead of feeding the electricity into an external grid or disconnecting part of the system, the surplus power is stored in batteries for its use at moments when there is no sun.
Such systems have been long operating with manufacturers like IPAR Electronika, Enerconv, Power Router and recently other top brands as Fronius, Zigor or Victron, but it is only now that they are taking a real boost.
These systems concentrate all the electronics needed to control the hybrid installation on a single device, preventing configuration problems. There are, however, other fully isolated hybrid network facilities when operating on the solar or battery mode, where inverter-chargers are used to achieve similar functions. With the former, however, the charge controller is avoided and the batteries can be managed better, increasing efficiency and regulating their charge and discharge cycles.
The advance of the new batteries will help these systems have a greater presence, because until now the largest bottleneck for price and performance of such facilities are storage systems.
The most widely used batteries to date have been the lead-acid, whether in liquid or gel version, gel and AGM gel batteries. These devices have the problem of a short life cycle and little depth of discharge (ie, do not allow much of the stored energy to be used), thus increasing the costs of facilities and decreasing performance.
For some years no, new storage systems have been developing of which the most- often used are the lithium ion batteries. These batteries have already reduced their cost by one third in the past three years, I still remember the first time I used them their price was five times above the lead-acid ones, and they have improved their performance for use with solar energy.
For some time now, such batteries are being talked about by almost everyone thanks to Tesla’s ambitious development plan but it is not the sole manufacturer that focuses on such batteries, Fronius’ project of inverter with batteries use lithium ion batteries, and other manufacturers like Panasonic or Saft.
These batteries are noted for their small space compared to previous batteries and especially their high performance, allowing to almost unload them up to 100% (the former could not exceed 60% without avoiding damages) and their high lifetime, which is 3 to 4 times higher than that of the lead-acid batteries.
Despite rumors, these systems are neither penalized nor prohibited nor will they be penalized, and they can be used in any installation that requires them in compliance with the necessary security elements.
There are new studies of batteries using organic materials such as grapheme or zinc-air flow based systems that promise lower costs and improved yields in the coming years, but now we must focus on promoting the use of the most effective today which are lithium-ion batteries to promote self-consumption and, why not ?, allowing the user to disconnect from the network.