My Solar PV Output For 2024
A couple of years ago, I had 5.8kW of solar panels and a 5kW battery installed on my (fairly typical) Dublin house.
The tricky part with solar PV is that, while you may have a set of solar panels, these may not be generating electricity at the time you want to use it. Even with a battery, your available stored power may wind up fully discharged by 7pm, leaving you running from expensive, non-renewable grid power for the rest of the evening. And up here in the high latitudes of northern Europe, you just don’t get a whole lot of solar energy in December and January.
2024 was the first year in which (a) my panels and battery were fully up and running, (b) we were using a day/peak/night rate for grid electricity, and (c) for much of the year I had load-shifting in place; in other words, charging the battery from cheap night-rate electricity, then discharging it gradually over the course of the day, topping up with solar power once the sun gets high enough. As such, it’s worth doing the sums for the entire year to see how effective it’s been in real-world usage terms.
The total solar power generated across the year was reported from my Solis inverter as 4119 kWh.
Over the course of 2024, the entire household consumption comes to 8628 kWh. This was comprised of a fairly constant 800ish kWh per month, across the year; we still have gas-fired heating, so the winter months generally use gas energy instead of scaling up our electricity consumption.
Of that, the power consumed from solar PV was 2653 kWh (reported from the Solis web app as “annual PV to consumption”), and that from the grid was 5975 kWh (reported by the ESB Networks data feed).
So the correct figure is that 30% of our household consumption was driven from solar. This is a big difference from the naive figure of 4119/8628 = 47%; you can see that a big chunk of that power is being “lost”, due to happening at the wrong time to provide household power.
Of course, that power isn’t really “lost” — it was exported to the grid instead. This export comprised 1403 kWh; this occurred when the battery was full, the household power usage was low, but there was still plenty of solar power being generated. (Arguably a bigger battery would be worthwhile to capture this, but at least we get paid for this export.)
There was a 2%-4% discrepancy between the Solis data and that from ESB Networks; Solis reported higher consumption (6102 kWh vs 5975) and higher export (1465 kWh vs 1403). I’m liable to believe ESB Networks more though.
In monetary terms:
The household consumption was 8628 kWh. Had we consumed this with the normal 24-hour rate tariff, we’d have paid (€236.62 standing charge per year) + (8628 at 23.61 cents per kWh) = (236.62 + 8628 * 0.2361) = €2273.69.
Checking the bills received over the year, taking into account load-shifting to take advantage of day/night variable rates and the power generated by the panels, and discounting the one-off government bill credits — we spent €1325.97 — 58.2% of the non-solar price.
Here! Have some graphs:
