Solar Panel advice

ian1246

Hi Guys.
             I'm in the early stages of looking into getting some Solar Panels.

We have a detached house with 2 South East Facing Roofs on the house itself and a detached extra-deep (roughly 2.5 car lengths) Garage with a South Facing Roof, albeit the South-facing side of the roof faces towards our neighbours and the garage wall represents the boundary itself so I don't think it would be suitable for mounting solar panels?

Our Energy use for 08th August 2022 to 08th August 2023 is projected to be 3,359 Kwh (using historic date from April 2022>August 2022 to supplement future energy use).

What size system would people recommend we look into getting and is Battery Storage worth it? (potentially looking at Octopus Flux, given we are already a Octopus Customer).

From my initial research using this calculator: Solar Energy Calculator | Energy Saving Trust

A 4kwh Solar System, with import costs of 34pence per Kwh and export of 15pence per Kwh (Octopus Tariff) would benefit us £755 vs. the same system with a Battery (13kwh), benefitting us £958. Then factoring in the 10% Energy loss from transferring to/from the Battery, this means we would have to import around 1,200 Kwh's of energy over the course of the 12months, which assuming we utilised the night-time Tariff for Octopus Flux to charge the battery, would save us another £159ish (1200 x13p tariff difference) - so a total benefit of £1117.

Am I missing something? Is my maths roughly where it should be?

If so, the issue then comes down to the cost of Solar - from what I can gather (again, using the above calculator), the rough cost is going to be £7000 vs. £14500 between the different systems, so a return of 10.78% vs. 7.703%.

 Are these figures roughly correct for what I should be expecting to pay for the 2 systems? If so... its seems a no-brainer for us to just go for just Solar-Panels, which leads me onto my next point:

Does anyone know much about Eon's Solar Panels Deal? They are advertising a 12 Solar Panel, 4.74Kwh system from £8262, paid back by 3 years of interest-free credit (£230 per month, which is comfortably affordable for us).

That seems expensive, except if I took the £7000 capital we would otherwise  be looking at paying outright with a different company and stuck it into a 4% Interest account if we went with Eon, that would earn £840 in the same- 36month period I would be paying off the Eon-Solar Panels, with the benefit of having that £7000 available for an emergency.

Whilst we can afford the £7000 outright now, it would leave our savings uncomfortably depleted, to the point we would probably have to look at getting Solar Panels next year instead to be on the safe side, at which point 1.) We wouldn't have benefitted from having the Solar Panels 12months earlier (savings of £755ish in that period) & 2.) Solar Panels may increase further in cost in the same time-frame.

Basically, the extra cost for Eon's panels (from £8262) may potentially be off-set by the interest-earnt on saved capital (£7000 at 4% interest - £840) & 12month's earlier-gain from Solar (£755), putting the overall cost of Eon's Panels at (£8262-£1595) at £6667.

Obviously, the quotes may come in differently - but at the moment I'm just after some thoughts/advice from those of you with more knowledge - does the above seem roughly right from your experiences?

ABrass

Your maths seems broadly right. Apart from your quotes for kit, they're rubbish.

A 4kWh system should not be above £6,000. Even that isn't a good price. A 5 or 6kWh battery shouldn't bump the price up more than 3-4,000. My kit was installed in Sept and cost £12,000.

Batteries might or might not make sense depending on the shape of the electricity market in the future and longevity. I went for one and am enjoying it.

llewdiskram

Hi Ian, I'm also looking at getting solar panels and battery.

E.On isn't available for me, so I don't know the details, but it is quite high as a battery is roughly 4k.

Make sure any companies you use are MCS certified or equivalent and have other accreditations and get a few quotes to compare.

I have 10 quotes and it has been whittled down to 3 companies as others don't have specific accreditations.

Good luck!

Screwdriva

Your initial research is broadly accurate (& impressive). For your relatively low consumption, a battery will only hurt your return on investment timeframe. I'd give the battery  and EON a skip. 

For your own benchmarking, a 12 SHARP 410W panel system + 12 SolarEdge optimizers + SolarEdge 5000 inverter will cost less than £6500 installed. That's with a 20+ year warranty on everything + G99 included. 

1961Nick

In your position I'd be looking at spending no more than £7500 on a 4kWp array, a hybrid inverter & a Pylontech US5000 battery.

Buying the battery at the same time as the panels saves the Vat - a hybrid inverter doesn't cost much more than a solar inverter. 

Screwdriva

1961Nick said:

Buying the battery at the same time as the panels saves the Vat - a hybrid inverter doesn't cost much more than a solar inverter. 

Not necessarily. You can always add an additional panel with the battery at a later stage and pay zero VAT. 

Alnat1

An extra panel might mean scaffolding again, better to get what you can on the roof in one go.

ian1246

Thank you for the feedback guys. What I am getting is that Eon are charging significant amounts more for their kit vs. other suppliers.

If I could find a supplier to fit a 4Kwh system for below £6000, that would be fantastic news.

How much extra would I be looking to pay with a Slate roof?

swal87

Screwdriva said:

Your initial research is broadly accurate (& impressive). For your relatively low consumption, a battery will only hurt your return on investment timeframe. I'd give the battery  and EON a skip. 

For your own benchmarking, a 12 SHARP 410W panel system + 12 SolarEdge optimizers + SolarEdge 5000 inverter will cost less than £6500 installed. That's with a 20+ year warranty on everything + G99 included. 

I would disagree on the battery statement. Lots of people are getting batteries without solar. on Octopus Flux you can discharge back to the grid at peak rate, and charge at super cheap rate in the AM and speed up ROI. I would not be without a battery even if it is to ride out cloud cover when you want the kettle on.

Screwdriva

swal87 said:

I would disagree on the battery statement. Lots of people are getting batteries without solar. on Octopus Flux you can discharge back to the grid at peak rate, and charge at super cheap rate in the AM and speed up ROI. I would not be without a battery even if it is to ride out cloud cover when you want the kettle on.

If you're able to back this statement up with an actual financial comparison, I'd be more than happy to concede that a battery makes sense. Do bear in mind the 12 year life of a top tier brand of battery and the current Agile import and export tariffs in your analysis.

This calculator should help. 

Alnat1

My average export rate over the last month on Flux was 26.39p (av. 9.1kWh/day), import 21.4p (av.3.36kWh/day)

Also pretty sure my battery will not suddenly cease to work on it's twelfth birthday. It may have a bit less capacity than a new one, but will still work.

What sort of rates can you get without a battery?