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Solar Equipment Guide All the parts of a domestic solar panel system explained

What are all the parts? What do they do? How does the electricity flow?

Here we'll spin over all the main components, what they do, and how the whole system works both when the panels are generating in the daytime and when they are off at night.

Section 1: Main components of a domestic PV solar system

There are 5 main components to a home electric solar panel system:

  • Solar panels
  • Roof mounting system
  • Inverter
  • Storage battery (optional)
  • Hot water immersion diverter (optional)

Let's go through each one.

The Solar Panels

The main part! The solar panels produce DC (direct current) electricity at varying voltage (depending on the conditions and how they are connected together). They work both in direct sunshine and on cloudy days too.

More about Solar Panels

Roof Mounting System

The first part of the installation is fitting the roof mounting system. It's effectively a big frame that's attached to your roof, for the solar panels to be attached to. It can be attached to almost any type of roof, though some are easier than others. We'll always come and check out your roof in person before giving you a final system design, just to check the plan for the mounting system.

More about Solar Roof Mounting


The DC electricity produced by the panels needs to be changed to AC (alternating current) for your house to use. That's the main role of the inverter. Your solar panels also produce a varying voltage depending on the sun's strength, and it's the inverter's job to convert that to a nice consistent 240V which your house runs at.

The inverter is also the brains of the system. It controls where the power flows to and from, and also logs all the data and sends that out to the various apps that you can monitor your system on.

More about Solar Inverters

Storage battery (optional)

An optional part of the system is a storage battery. South-facing panels will produce the largest amount of electricity during the middle of the day, whereas most households tend to use more electricity in the mornings and evenings. The idea of the storage battery is to store the excess power from the middle of the day to use during those peak consumption times later on.

You might hear the term "hybrid inverter". That's an inverter that can also connect to storage batteries, so you'll need a hybrid inverter if you have storage batteries. Again, the inverter is the brains of the operation, controlling when the battery is charged and discharged.

However, there are other options for the excess electricity, such as a hot water diverter, or selling the power back to the grid.

More about Solar Storage Batteries

Hot water immersion diverter (optional)

Another use of excess electricity is to heat your hot water tank through an immersion heater. This is known as a hot water diverter, and it tends to be set up to kick in when you have spare power and your storage battery is already full.

Don't worry if you do not have an immersion element in your hot water tank, you can add a Willis Heater externally that does the same job.

More about Hot Water Immersion Diverters

Section 2: Where the electricity from your panels goes

Domestic PV solar systems are very clever and divert electricity to make the best use of the power you are generating.

Domestic solar panel installation showing all components such as the solar panels, inverter, diverter and battery
Priority #1: running your home

Electricity from your solar panels is first used to run your home. The electricity always goes here before anything else like charging a storage battery or hot water diverters.

Priority #2: charging the battery (if installed)

If your solar panels are producing more electricity than your home currently needs, then any spare power will go to charge your storage battery if you have one.

Priority #3: hot water diverter (if installed)

If you still have spare power coming from your panels after all the above, then the hot water diverter will kick in (an optional part of a solar PV installation). If there is spare electricity that your house doesn't need, and your battery is already full, then the electricity will be diverted to an immersion heater in your hot water tank to create hot water for later.

Priority #4: responsive electric car charger (if installed)

Certain models of electric car charger (for example, the Zappi EV car charger) can be connected to your solar PV system, and set so that they take any overflow excess power. This is a great way to use any spare electricity, as the car charger will turn on and off automatically to soak up any unused electricity.

Priority #5: give / sell power back to the grid

The final use of unused electricity generated by your panels is to give it to the grid for other people to use.

Before 2022, excess electricity was given to the grid for free. A feed-in tariff has now been introduced in Ireland, which means you will get paid for any excess electricity you give back to the grid. The rates depend on your electricity supplier.

More about solar feed-in tariffs in Ireland

Section 3: What if my house needs more electricity than the solar panels are generating?

If your home needs more power than your panels are generating, then the system will top it up firstly by drawing from the battery, and then from the grid as well. The system can use all three sources of electricity at the same time.

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