Already more than one third of the energy produced worldwide is generated from renewable sources. As the cost of photovoltaic panels and batteries keeps decreasing, solar self-consumption is quickly becoming a popular goal in countries and areas blessed with plenty of sunshine such as Costa Blanca South.
But there are still many doubts when it comes to taking the step into solar energy in a home. Is it possible to cover all the energy demand of a home with solar panels? How do you know how many panels to install? What happens when the sun does not shine or during the night? Is it possible to somehow store surplus energy for use at another time?
Today, it is technically and economically possible to cover the energy needs of a home through solar panels and batteries. A prior study is always necessary to measure both elements and to be able to confirm that the solution is viable.
Necessary Elements for Solar Self-Consumption
The size and capacity of the installation of solar panels and batteries will vary depending on the needs of the home and the objectives sought. It is one thing to use photovoltaic energy to save and reduce environmental impact, and a completely different kettle of fish to be completely self-sufficient or to bring electricity to an isolated building. In any case, an installation of this type must always include the following elements:
Responsible for producing electricity from sunlight.
As the panels generate direct current, an inverter is needed to transform it into the alternating current used by household appliances.
Accumulators or batteries
These are not always necessary as the surplus production can be fed into the electrical network. But if we are seeking a real self-consumption that covers the energy needs of the home when the photovoltaic production decreases, then we need accumulators or batteries.
These systems control, in real time, the production of electricity and the state of the batteries.
Today, it is technically and economically possible to cover the energy needs of a home through solar panels and batteries.
Types of Storage: Lead, Lithium and Virtual
If there are no storage systems involved, electricity is always consumed at the time it is produced. Thus, in a solar self-consumption installation, we usually find imbalances between energy demand and energy generation. Consider, for example, that we have six solar panels in our house which, at noon on a sunny summer day, produce 4.5 kilowatt hours (kWh). If at that moment we have the oven, washing machine and air-conditioning running, the demand will be quite adjusted to the production – very good!
But if no one is home at that time, what happens to the energy? In this case, electricity can follow two paths:
- It can be fed into the electricity grid, where it will become part of the general energy mix.
- It can be stored in batteries for later use.
The two main storage technologies today are lead batteries and lithium batteries. Lead batteries are used in isolated installations due to their high capacity and low cost. Lithium batteries – whose prices have fallen 97% since 1991 – are gaining ground in the domestic sector because they do not have a memory effect, their charging cycles can be adapted to the best interests of the user, they are less heavy, and they do not require maintenance.
In addition, some electricity retailers have developed the concept of a virtual battery, also known as a piggy bank or solar coin purse. These systems monetize the excess electricity that is fed into the network from the home, based on the price in the wholesale energy market. This way, surpluses can be used to offset the cost of electricity consumption through the electricity grid when solar generation does not cover the household demand. It is a halfway solution in which the users charge for the energy they produce and do not use.
Factors That Influence a System of Solar Panels and Batteries
When deciding how many solar panels and batteries we need in our home photovoltaic installation, we need to consider the following factors:
What is our objective?
To lower the costs of our electricity bill or have emergency support in the event of a blackout, it may be enough to rely on a single lithium battery. But if we want to be completely independent of the network, we will need an installation with much more storage power.
What are our consumption habits?
Traditionally, we are used to choosing between many different electricity rates available in the market. Also with solar systems, it will be necessary to carry out a study of our energy consumption habits and basic energy needs. For example, if our demand is minimal at night, we will not need much storage.
What is our photovoltaic generation capacity?
Are you living in single-family home with a large roof facing south … or in a block of flats? There are some online tools to help you assess your needs, but it is still important to have a detailed study carried out by an expert.
How many solar batteries will we need?
Considering all the above elements – objective, consumption habits, generation capacity – it will be necessary to calculate the average energy produced and the real energy that will be necessary at different times of the day. The difference between the two will give us clues as to how much minimum storage capacity must be installed.
To find out the energy demand and the consumption profile of our home, we need to analyse how the home has behaved in the past year, and whether changes will take place in the coming months or years:
- Will we buy an electric car?
- Will we have an aerothermal system installed?
- Will we reduce our use of gas in favour of more electrical appliances?
We can basically review the electricity demand of each of our electrical appliances and systems and multiply it by the number of hours that we expect them to work while the photovoltaic panels are not producing at their maximum. For example, if we need our refrigerator, which consumes 50 Wh, to work for 12 hours regardless of solar production, we need a battery capable of supplying 600 Wh per day.
The calculation must be repeated for each of the household appliances. The final sum will provide data on the storage capacity that we must have, based on our objectives. It is estimated that the batteries needed in an average home with an average installation of solar panels can cost between €7,000 and €9,000. This cost can now be brought down with an EU subsidy of up to 70%.
A decade ago, having a home powered by photovoltaic panels with its own storage system was practically impossible due to costs. Today, solar self-consumption is really within our reach.
We at Casa Botnia Building are happy to provide our home buyers with the exclusive expert solutions discussed above!