Technical topics:
Whilst the photovoltaic systems are technically standard already, the technial development on the field of electrical storage is still running full steam and surely is not finished by far. Therefore currently it is impossible to say for all potential users, which kind of technology will be the most reasonable one for the certain application. It is not without reason that e.g. the German governmental incentive scheme for storage units is open to every kind of technology.
In the media you often can hear several catchphrases which the consumer up to now canīt do anything with. Therefore we would like to explain shortly some of the most important terms. Please do not hesitate to contact us for more detailed questions to this matter.
Lead batteries or lithium accumulators:
This point causes the biggest controversy in storage unit business right now. Proven old school lead battery, which everybody knows from his car, opposes modern and stylish lithium technology, which has been used mainly in small applications as mobile phones and laptops up to now. From general point of view both system designs can be used according to each users preference. In my own opinion both technical and commercial development (mainly driven by E-Mobility research) will bring the breakthrough for the lithium systems in the oncoming years. One very important point for the consumer: Double check in the offers the nominal but especially also the usable storage capacity! Lead batteries are meant to be unloaded to 50 % of nominal capacity only. Lithium accumulators have got a better discharge limit of 90 % of the nominal capacity.
DC or AC System:
Over this question is argumented fiercly with details as marginal better efficiency factors back and forth. For the user in the end there is one important point to be respected, retrofitting of DC-systems to already existing PV installations is complicated or in a lot of cases even impossible!
Life time of batteries:
Concerning lifetime of batteries is differentiated between two terms: The calendarical lifespan and the cycle resistance. The batteries used in the currently available PV electricity storage units are dimensioned in a way, that the calendarical lifespan will not be reached in most of the cases. Due to the daily loading and unloading (cycle) the battery is losing capacity with the time, what will be the main factor for necessary replacement. E.g. therefore the German incentive scheme forces the suppliers of such units to provide respective performance warranties.
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