Over recent years, the term “auto-consumption” in the energy sector has become more common in colloquial language, not always in a positive sense and sometimes with scepticism. Successive changes in legislation have led to confusion on the part of businesses and residential users that, either by conviction or by economic interests, were potentially interested. However, today we can say that we have reached the point where an energy production installation is equal to or less expensive than the same energy contracted to the public network. Photovoltaics, as it says Vozpopuli in its post written by Antonio Muñoz Velez,

“has ceased to be a teenager, much less a spoilt child.”

The auto-consumption in Spain is finally a reality in sight.

However, some people are sceptical about real energy savings of a photovoltaic installation, or even if the return on investment makes it interesting to consider this technology. It is shown that a facility today can run completely autonomously through the different systems that exist, but it is true that pretending to supply 100% of the energy demand of any facility can still be somewhat expensive and lead to periods of more distended amortisation so users would be willing to assume. So the question must be asked: do we really need to supply 100% of our energy demand? To see a specific case, if your house is in an area of difficult access to public electricity supply you will need to produce the energy it consumes fully your own way, so it will end up producing 100% of what you need to consume. On the contrary, if you do have access to the public network, it would be possible to establish a project of photovoltaic energy consumption by only provides a part of the energy demand. That way you can save a significant amount in the initial project cost and even significantly reduce the return period. The same would happen in an industry or a services facility. If further installation requires more energy during the day, ie its consumption occurs primarily during daylight hours, it is much easier to get this cheaper because it does not need to store energy using batteries that considerably increase the project cost as a whole. In fact, as national legislation is today, according to RD900/2015 based on an earlier draft, the known Net balance which in theory allows pouring into the public network surplus energy produced is not allowed in Spain. This is an additional argument when considering how to maximise the energy produced, if we decided on photovoltaics instead of producing surplus and stored in batteries.