Are you thinking of getting solar panels? Here's your checklist

Analysis: There are a few things to consider before you take the big step to stick solar panels on the roof of your house.

Solar energy is a renewable, sustainable energy source, whether it is solar panels to heat water or solar photovoltaic panels to make electricity. If you're thinking of switching, here's a checklist for the most important requirements for a solar photovoltaic panel installation.

Are you facing south or east-west?

Ireland is in the northern hemisphere, so the sunrise is in an easterly direction and sunset is in a westerly direction, meaning the two options for a photovoltaic panel installation are either south facing or east-west facing. Depending on the roof space available, south facing panels will yield a higher output for a shorter time period but east-west panels will yield a lower output for longer periods throughout the day.

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What's your roof access like?

This is a primary concern for the initial installation of the panel frames, individual panels, and interconnecting wiring. There will need to be a route to transfer the equipment from the delivery vehicle and there will need to access to roof for a day or, depending on weather conditions, two days at the most. This will require a combination of safe scaffold and ladder access to the roof.

There will also be a requirement to access the photovoltaic panels at least once a year for cleaning to remove dust, organic matter, bird droppings etc. Dirty panels can reduce output by up to 20% without annual cleaning.

How much space does the equipment take up?

The location where the solar photovoltaic equipment is installed must be safe for installation, replacement, maintenance and equipment observations. There must be a safe route identified from the external panels to the wall mounted Inverter and from the inverter to the the main household incoming power distribution board.

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The ideal location for the inverter would be at ground level, with a wall space of 2,000mm wide x 1,500mm high and located 1,200mm above ground level. There will be requirement of 1,200mm clear access in front of the inverter panel (clear all the time). This will comply with BS7671 wiring regulation sand allow the electrical installation to be certified. This will apply to the storage batteries or the Eddi or equivalent hot water diverter equipment, if theses options are selected.

It's recomended to have the new inverter panel installed in an easily acessible ground level location for intermittant display panel observations and assessment. There will be a requirement for a wifi signal adjacent to the inverter to allow for the mobile application to read and transmit the realtime electrical energy generation data, a signal booster may be needed here.

Think about cables and where they need to go

The following cable routes need to be considered and verified to minimise costs and unforeseen works. Cables from the solar panels will penetrate the roof with a waterproof grommet and are typically run at attic or roof thruss level and connect to the inverter panel. Cables from the inverter must be routed to the nearest distribution board, which can be in a garage or the distribution board in the house. If the garage distribution board and the main dietribution board are seperate, the interconnecting cable size must be verified as this may limit the capacity of your solar photovoltaic installation.

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If there is cable ducting in place a new cable can be pulled, but would need to be identified at the quotation stage. If an external car charging point is included in the installation, there will be a seperate cabling installation for that. Finally, if there will be a storage battery or an Eddi or equivalent hot water diverter equipment installation, there will be local cabling associated with these.

Your existing electrical installation

A new solar photovoltaic equipment installation will be tying into the existing domestic installation so it is important that the existing installation is both safe and meets the current regulations. Otherwise, the solar photovoltaic equipment installation cannot be completed.

To allow for any surplus electricity generated to be fed back to the ESB grid for payment, there must be an ESB Smart meter in place. In some cases, this could take up to three months depending on the roll out plan in the locality so the secret is to apply for this as soon as possible.

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Your new installation will be connected to your existing distribution board so there will need to be a minimum space requirement for three double isolator units, two of which will be used and 1 space for a future spare, depending on the equipment being installed.

For the Eddi or equivalent hot water diverter equipment installation there must be an electric immersion heater in the hot water cylinder. For larger hot water cylinders, there may be both top and bottom immersions controlled by a bath/sink switch, the control of these will be replaced by the Eddi or equivalent diverter. If you have or are planning to use an electric car, it may be worth investing in car charging port.

Getting your BER rating

There's a €2,100 grant available from the SEAI (down from €2,400 in 2023) if you use an approved solar installer and a revised BER assessment is completed afterwards. Some solar panel installers include a post BER assessment in their costs and some do not (the cost is typically €250), so it's important to clarify this.

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If you have completed a BER assessment on your dwelling recently, it is more cost effective to go back to the same BER assessor as they will give you the benefit of any recents upgrades in case you have no evidence of it. If the dwelling does not have an existing sustainable energy source, the solar photovoltaic installation will improve the BER rating.

How long will it take for the solar panels to pay for themselves?

This is always the crunch question and most solar providers will give an indicative payback evaluation with the equipment quotation. The most important criteria for payback for a solar photovoltaic panel installation is to use the generated electricity for household daytime consumption, hot water generation with an Eddi panel, charging your EV car with a Zappi unit or storing your electricity in a battery for use during darkness.

Currently in Ireland, most electricity suppliers will take back any surplus solar electricity at a rate of 50% of the associated day rate and this credit is deducted from the electricity bill. This may not always be the case as many of the electricity suppliers in Europe do not offer a payment for surplus household solar electricity. To avoid any hidden post installation costs, it is advisable to request a full survey at the time of the final cost proposal from the solar PV installation contractor.

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The views expressed here are those of the author and do not represent or reflect the views of RTÉ