has anyone managed to offset their ESB bill with solar alone?

My setup is still evolving, but I started the home process exactly 2 years ago and the move to EVs (both cars) 9 years ago. If you have the patience, my summary is below. If not…the fast answer is my bills are reduced, not covered in full, but there's more to it than that.

Home is 3 bed semi-d with converted attic. BER 2024 is B2.

Single phase supply, effective 12kVa MIC.

Heating is Gas Boiler, also heats cylinder when fired. Also have 5kW solid fuel stove for luxury, no back boiler. €300/yr on coal.

3 EVs in the house. Combined weekly kms circa 1000.

5.2kWp Solar PV and 30kWh DIY battery added 2 years ago.

3.6kWp Solar PV and 15kWh DIY battery added 1 year ago. Total 8.8kWp PV and and 45kWh battery. We use around 40-50kWh daily, including for EVs.

Off the top of my head, I've probably spent about €12k on my solar and battery setup. I didn't count the pennies.

Before the solar and with 2 EVs, we had used 18,000kWh of electricity in 2023. Stopped counting when we got solar PV, but our electric bills were averaging weekly €100 before solar.

Gas is much better, spending only €500 - €600 per year, including gas hob for cooking.

My entire electricity bill for last year: Around €830

That's what I was seeing every 2 months…so my bill is about 16-17% of what it used to be, despite adding a third EV to the mix and another baby born a year ago.

How does my setup work?

Energia EV rate. I charge the batteries 2-6am with the 5kW inverter and a 3kW rectifier. We charge 1 EV on the main charger and another on a granny charger and switch each night. The house mostly uses the batteries energy except when the load is above 5kW which the inverter is limited to. I dump excess PV throughout the day and any extra from the batteries from midnight - 2am, except from November through February when I direct PV into battery and don't dump excess.

So, my energy costs are about €1,400 per year, but they would be well above €6,000 without the existing setup.

@graememk mentioned cost to heat water with gas being cheaper and he knows his stuff, but this might be interesting to note. I'm in the middle of a heatpump course and using my own house as an example, just finished the calculations yesterday.

Without discounts on either utility, I am charged 11c/kWh of gas. With a boiler efficiency of 90%, lets say it's 12c/kWh for every unit of heat. I used the higher EV night rate of 12c/kWh, so the same as the gas rate, but remember, the efficiency is not 90% for the heatpump, it's on average 300%, reducing the cost of heating to around 4c/kWh because the HP would be running off cheap electricity the whole time!

Now you may no longer need to have a gas connection, so cut out the standing charge too. Not bad.

My Gas boiler probably has 2 years of life left and runs below 80% efficiency. Doing the sums, with grant included, it will only cost me €2,300 more to install a heatpump and upgrade radiators. The heatpump will take 16 months to pay off the difference based on my calculations, which assumes like for like heat production per year. In reality, we will spend the same on running costs with the heatpump, but the home will be kept at comfortable temperature year round (instead of gas boiler boosts) and hot water will be cheaper.

What all this means is that I will have already recovered my investment this year and my energy costs are much, much lower than they would be without solar PV and batteries. I'm by no means well off….and struggled to put everything together, piece by piece. Crippling electric bills pushed me forward.

I hope that's helpful.