Going Solar Part 5 – Our PV Systems Actual Generation Figures After First Full Year

Our Solar Array was installed on the 12th September 2016 so last week saw it reach its first anniversary.

In Part 2 of our Going Solar series, I wrote that our system “has a predicted annual generation figure of 3,400 kWh“. So how has it performed compared to that expectation?

Facts & Figures

Well I’m happy to report that despite what was, in part, another fairly grey and miserable Northern Irish summer, our solar array has out-performed predictions.

Sunny Portal - Solar PV 1 Year Output

With 3,497 kWh’s generated in the last year we can calculate that the ROCs payments will be around £420, slightly above our prediction (£408).

We’ve had an export meter installed since 14th December 2016 and have only sent 385 units back to the grid since then (and 185 of that was when we were away on holiday). So our predicted export income of £51 will probably end up more like just £14.

But of course this is good news, it means we really are using the vast majority of what we generate.  It’s much better to use the electricity yourself (rather than have to buy it in at £0.13), than to give it away for only £0.03 per unit. I estimate our self-consumption rate at around 87% which is even better than the 70% I had predicted.

SMA InverterPredicted

1. EXPORT: 3,400 kWh x 50% x £0.03 = £51
2. ROC: 3,400 kWh x £0.12 = £408
3. SAVINGS: 3,400 kWh x 70% x £0.1343 = £319

TOTAL: £778
Payback ~ 6.4 years


1. EXPORT: 3,497 kWh x 13% x £0.03 = £14
2. ROC: 3,497 kWh x £0.12 = £420
3. SAVINGS: 3,497 kWh x 87% x £0.1343 = £409

TOTAL: £843
Payback ~ 5.9 years

While the government incentives are now gone (check out Part 2 for an explanation of ROCSs ) prices have continued to fall. I recently noticed a local company advertising a 4kW system for £3,499 + 5% VAT installed.

We’ve hit 87% self-consumption with the help of the Solar iBoost , but with an EV in the garage, the dream is to install a battery and reduce our reliance on the grid as much as possible. Check out Robert Llewellyn’s Fully Charged Show video which shows what can be done. Yes, the economics aren’t there yet, but it’s getting closer and closer.

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Read the full Going Solar Series…

Going Solar Part 1 – Installing a 4kW PV Array at the Automated Home

Going Solar Part 2 – Costs, Incentives & Payback Time

Going Solar Part 3 – I Traded in my Range Rover for a Nissan Leaf

Going Solar Part 4 – I Measure Every 24/7 Electrical Device in the Automated Home

Going Solar Part 5 – Our PV Systems Actual Generation Figures After First Full Year

Going Solar Part 6 – Entire First Years ‘Fuel’ Costs for Nissan Leaf EV – £235

Solar Panel Co NI

Last update on 2024-04-08 / Affiliate links / Images from Amazon Product Advertising API

5 Comments on "Going Solar Part 5 – Our PV Systems Actual Generation Figures After First Full Year"

  1. that’s good … thanks for posting, too …

    was reading about PVT – hybrid PV & thermal … idea being that PV need to run cool, so sunniest parts of the day can be less productive than they might be …

    with PVT, the thermal part produces around three times as much as PV, and the PV output is increased by 25%+ thanks to the heat being taken away by the thermal …

    anyway, interesting, but wondered if you’d noticed the effect of heat on output – of course the gain goes up with solar intensity so the effect might not be so noticeable when looking at the output over a day, even when plotted against time … plus, having them mounted with plenty of airspace / wind-space probably helps a lot …

  2. the PowerWall video was good, too … looking forward to the prospective upgrade, to allow it’s use to cover mains power-cuts – we’re out in the sticks, so perhaps more prone to cuts than most, especially when storms go by …

  3. PS: would be good if they included a connection for an emergency generator, too, to allow topping-up when power-cut is extended …

    with both the generator & the Powerwall needing mains isolation during the powercut, it could be a convenient & cost-effective way of doing it …

  4. How beneficial have you found the iBoost to be?

    I’m debating thermal or PV solar at the moment, and have lots of south facing roof space for both systems if need be. It’s just a 100l tank for 2 people, but the decision making process is interminable.

    I need convincing that the winter efficiency of PV into the immersion coil is enough to offset LPG heating costs!

  5. @Kyle – In a lot of days in December / Jan you can basically forget about having any kind solar PV generation.

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