We’ve seen different weather conditions in Dublin in the past 2 weeks – its rained a bit, some days were cloudy, and some have been amazingly sunny and pleasant like last weekend. And the Irish who are known for their humor and wit do not shy away from cracking a joke or two about their weather over a pint of beer. But taking a look at the data, you notice that Ireland actually receives a fair amount of harvestable solar energy, measured as solar irradiance. Dublin actually receives approximately the same annual irradiance as Waldpolenz (east of Leipzig in Germany) which has a very large solar farm!
The map above shows the annual solar irradiance across europe in kWh/Sq. meter (total solar energy received on 1 Sq. meter of earth in 1 full year). While plants harvest a tiny fraction of this energy, commercially available photovoltaic (PV) panels are able to harvest about 15% of this. To put things in context, 1 kWh is the amount of electricity needed to power a 50 Watt bulb for 20 hours. A one-bedroom house in Ireland might consume about 3100 kWh of electricity in 1 year.
But is solar power expensive? Well, it depends on the price of solar panels and the electricity they generate during their lifetime. Here is a sample calculation: A 1kW peak PV system (which might require 7 Sq. meter of roof-area to install) can produce approximately 850-900 kWh in 1 year in Dublin (orientation/tilt/technology play a role, check this). If these panels last for say 20 years (good ones last for more), they could produce 900 x 20 = 18000 kWh. If this PV system costs you 1800 Euros (maintenance/system size play a role, check the photovoltaic electric cost map), then you are effectively producing electricity at 10c/kWh for the next 20 years but investing in advance.
Electricity prices in Ireland have increased over the last couple of years (currently higher than EU average). I’d probably feel less guilty using these fancy cube-lit sidetables in my hotel room if they had been powered by solar 🙂