Location

Árainn, Co Galway

Name

Dara

Useful Links

SEAI: A Homeowner’s Guide to Solar PV

Impact:

• Financial savings of up to €1430 per year (depending on the electricity charge per unit)
• Carbon emissions savings of 949.5 kg CO2, equivalent to planting 67 trees.

What inspired you to do this?

We eventually want to be almost 100% self-sufficient in energy. We’ll stay connected to the grid, but hopefully not dependent on it. For that, we will need to add a small domestic wind turbine. We’re looking out for one that offers 3 things: 1) won’t endanger our bird life; 2) will have a 10-year guarantee; 3) will offer a maintenance contract. We are a family that also likes to grow our own food, build our own buildings (we built our own home), and let our kids learn outside of schooling.

What were the personal and or sustainability benefits?

The monitoring equipment is improving all the time. We now have an app called Solis that tells us what’s happening at any particular time. The EDDI [3] device also monitors all energy coming into the house, and lets us know how much PV generated energy is being used to heat the water. Eventually, I hope, we will have a monitor on our kitchen wall telling us everything we need to know on a simple screen. We’re not there yet!

Looking through our electricity bills over the last year and a bit, two bits of information stand out… 1) In July and August of 2024 we didn’t need any electricity from the grid during daylight hours. Our PV and battery storage was enough. I’m delighted about that. 2) Once we got the EDDI etc., working properly from December 1st onwards (we didn’t know it wasn’t working for a few months) we stopped exporting virtually any surplus electricity from our PV. From September to November, we exported €92 worth (when the system wasn’t working), but for the following full year, the total export of surplus electricity from our PV was €56. That measured success for us… we were using all the electricity we were generating – which is the most efficient and cost-effective way

What advice would you have for others to do something similar?

If you are thinking of installing PV at your house, remember that the most efficient use of your generated electricity is using it yourself. Exporting energy to the grid is not going to give you much payback. Therefore, if and when you can afford it, put in an EDDI [or other PV energy diverter] to heat your water with the surplus you generate, and install battery storage, so that surplus generated during the day can be used in the evening. 2 kW of PV is a good start, but 4 kW is better, especially if you have a busy household.

Notes and Calculations

The total electricity generated by the 2kW PV between October 2013 and March 2021 was 12318 kWh [you get a read-out of this from the equipment]. This averaged at 1,661 kWh per year. Over this period energy charges were approximately 20c per unit. This equated to savings of €332 per year. 

In September of 2023, a further 2 kW of Photovoltaic panels were installed, making it a 4 kW system in total. These second 2kW were installed on a flat, slightly slanted south-facing roof. A further 5kWh of battery storage and an EDDI system were also added. The EDDI takes surplus electricity generated by our PV and uses it to heat water in the hot water cylinder.

The total electricity generated averages 2860kWh per year, with a potential saving to us of €1430 per year, and a CO2 emissions reduction of 949.5 kg CO2, equivalent to planting 67 trees [2].

[1] We don’t take into account the change in heating system in our inpacts assessment. Switching from an oil burner to a heat pump system has a significant benefit in terms of carbon reductions. This benefit is told in another home energy story.

[2] 1 Tree offsets 14kg CO2

[3] We do NOT endorse or encourage the purchase of particular products. The reference here is for information purposes only.

Search our Community Stories By Map