Solar Panel advice

[Deleted User]

The Flux tariff works best if there is a large amount of exported solar - why, because the overnight import cost is high. In my case with a 6.35kWp and a Powerwall2, I will stick with Flux until late September then revert to another tariff with a lower import price.

FWiW, I would not base a buying decision on a beta tariff that could be withdrawn at anytime by the supplier. Most homeowners without a battery can only use 25 to 50% of the solar energy generated. A battery might increase this to 70%. It follows that if the predicted output of your proposed array is 4000kWh year, you might be able to offset 2800kWh of your home usage. This would give you a saving today based on a standard tariff of 35p/kWh of £980 per year plus SEG payments of 1200 x £0.15p/kWh or £180/year.

A few things to think about. To get SEG payments from Octopus, you must have a smart meter in a 30 minute profile. Octopus insists that you have a MCS Certificate for the installation, and your installer must provide you with DNO approval for your installation after commissioning. Octopus will then apply to your DNO for an export MPAN (a process that can take a few months) before it can start paying you SEG.

FWiW, advice given to me 3 years ago was get a battery at least twice the size of your Winter daily consumption. That advice has worked well for me even with the odd anomaly that comes out of Tesla’s battery charging algorithm. The battery overnight charge is based on the following day’s solar prediction.

ian1246

Just thought I'd reply and say thanks again for the advice - I already have a Smart Metre (fitted by Octopus October 2022!) so hopefully that is one less barrier to getting Solar Panels.

I have spoke to my wife - we've decided to contact a few local suppliers to get quotes to see just how much we are talking about here.

With regards to whether to fit a Battery? On the face of it, its not financially viable - however this disregards likely inflationary fuel rises.

Below is a screenshot of the spread sheet I've set up to work out the financial viability of investing in Solar Panels & then whether to look at Batteries as well.

We use 3,400 Kwh of energy every 12 months - with our Daily Use I think we would need a Battery able to discharge at least 8Kwh of energy to meet daily Kwh requirements (factoring in there would be a period during the day, even in winter, where we would generate a small amount of Kwh & then also the 4-5hour period at night when we can draw from the Grid at Night-rates directly, so the battery would only need to cover around 18 or 19 hours worth of use. In Winter, around 2kwh of our energy use is between 12am and 5am - combination of background draw & a 600 watt heater we have in our young sons room to keep it warmer whilst the central heating is off).

I'm hoping we'd be looking at around £4000 extra for that from the research I've done - if that is the case, then a battery does become financially viable when you factor in inflationary rises.

Screwdriva

ian1246 said:

I'm hoping we'd be looking at around £4000 extra for that from the research I've done - if that is the case, then a battery does become financially viable when you factor in inflationary rises.

Thank you VERY much for sharing your analysis. At ~3500 kWh p.a., you're nearly at the cusp of battery viability. That said, a couple things to factor in:

1) GivEnergy's 10.4 kW battery storage costs approximately £5K installed these days. And that's the cheapest brand with any semblance of warranty & aftersales support.

2) As they age, batteries lose capacity & efficiency. This is why GivEnergy (& other quality battery brands) offer a sliding warranty. For a component failure in year 10, you will only receive compensation worth 10% of the value, as an example. This degradation has a sort of opposite effect of inflation. It is safe to say that a battery will be replaced atleast once if not twice during the ~30 year life of a modern PV system. 

3) If you plan on acquiring a heat pump/ EV in the future, you should ideally invest in a modular battery system. This will allow you to scale up capacity as you electrify the household. 

Waywardmike

Screwdriva said:

1) GivEnergy's 10.4 kW battery storage costs approximately £5K installed these days. And that's the cheapest brand with any semblance of warranty & aftersales support.

the biggest battery they do is 9.5kWh?  Although with the current SOC issue you won't even get that some days...

I'd love to see a recent quote from someone who's managed to get a GE 9.5kWh battery (plus inverter, A/C or hybrid, as it's a closed system and won't work with anything else) installed for £5k.  An actual quote, not just "my installer can do it"...  The lowest quote I could get over a year ago was ~£5500 for a 5.2kWh battery, and that's before everything went wild.

94JDH

Waywardmike said:

Screwdriva said:

1) GivEnergy's 10.4 kW battery storage costs approximately £5K installed these days. And that's the cheapest brand with any semblance of warranty & aftersales support.

the biggest battery they do is 9.5kWh?  Although with the current SOC issue you won't even get that some days...

I'd love to see a recent quote from someone who's managed to get a GE 9.5kWh battery (plus inverter, A/C or hybrid, as it's a closed system and won't work with anything else) installed for £5k.  An actual quote, not just "my installer can do it"...  The lowest quote I could get over a year ago was ~£5500 for a 5.2kWh battery, and that's before everything went wild.

He's probably quoting the rough figure of its capacity as 9.5kWh battery is 100% depth of discharge, so the higher value is the rough allowance for this to meet the usable capacity.

[Deleted User]

I struggle to understand when it comes to solar and batteries the universal chant is RoI.

If I buy a car, I accept that it depreciate by 50% over 3 years. Similarly, if I spend £20k on a new kitchen, I just enjoy it and hope that if I decide to sell it will add a few £s to the sale. Why should be PV be any different?

FWiW, I currently I have PV solar and a PW2, and I am presently thinking of adding more panels to my roof. At today’s export prices, I will recover my additional investment in 6 years but I am doing it more for the satisfaction of getting free energy. It’s addictive.

PS: Tesla has just reduced the cost of a PW2 to bring it inline with SolarEdge’s battery. There is also a PW3 on the horizon.

ian1246

[Deleted User] said:

I struggle to understand when it comes to solar and batteries the universal chant is RoI.

If I buy a car, I accept that it depreciate by 50% over 3 years. Similarly, if I spend £20k on a new kitchen, I just enjoy it and hope that if I decide to sell it will add a few £s to the sale. Why should be PV be any different?

FWiW, I currently I have PV solar and a PW2, and I am presently thinking of adding more panels to my roof. At today’s export prices, I will recover my additional investment in 6 years but I am doing it more for the satisfaction of getting free energy. It’s addictive.

PS: Tesla has just reduced the cost of a PW2 to bring it inline with SolarEdge’s battery. There is also a PW3 on the horizon.

From my point of view: A Kitchen is for cooking in and entertaining guests. That is its sole objective. A Car is for travel, the nicer the car the nicer the journey.

Solar Panels though? They are to produce free energy - but in terms of the value the owner places on that free energy? Some no doubt will do it for environmental reasons, at which point Return on Investment is less important., but for others (I dare say... most), that free energy simply boils down to the £££ saved on energy use and the £££ generated from exports. In such circumstances - investing in Solar Panels is a primarily financial purpose, which is where the Return on Investment comes into the equation.

Frankly, I wouldn't be looking at investing in Solar Panels if there wasn't a financial argument in favour of it - the reduced energy bills will make me and my family wealthier in the long run by buying Solar Panels.

Bonus points since it will be helping the environment. Extra bonus since it will also hopefully boost our houses value (4-12%), not that we plan to sell. Extra Extra bonus points that it will likely drag our EPC rating up into a C Band (Or even a B band, when coupled with our other home improvements we've done since buying our house in 2021), which in the context of Mortgage Companies starting to limit offers for poorly rated properties in terms of Energy Efficiency, means it is future proofing our property for our re-mortgage (Or if ever we decide to sell).

The final consideration with our decision to look at getting Solar Panels is environmental - that there is now a push, increasingly via the law (I.e. Gas Boilers due to be banned in the future. New Petrol/Diesel cars getting banned etc...), for homes and households to move towards Carbon Neutral.

A lot of articles I've read reckon it will cost most homeowners somewhere in the region of £30,000 to bring their houses up to this standard. Its prudent to start making the move now, rather than waiting to be forced.

Solar Panels are an enabler to this objective - they will supply energy to either a Heat Pump or a Electric Charging point for a future vehicle in the future. By getting Solar Panels, it improves the economic/financial argument for our household to make the other improvements. Its a good foundation to get at the start of our carbon-reduction journey.

ian1246

So I've received my first quote through - total cost £5,727.56 including labour:

11 x Trina Vertex S 415W All Black Mono solar panel
Growatt MIN 3600 TL-X Dual MPPT 1ph (inc DC isolator) inverter
Emlite ECA2 extended cover
Shine Lan - Growatt
AC isolator - Projoy 20A 4-pole
IMO DC isolator 16A 2p 1string

Plus other required bits.

Our House would have 6 Panels placed on one roof 90 degree's from the South (Facing West I think), orientated at 45 degree's from horizontal - generating an expected 1793 KWh (Installed Capacity of 2.490)

Then another 5 Panels placed on our other roof, -90 degree's from the South (Facing East I think), orientated at 45 degree's from horizontal - generating an expected 1494 Kwh (Installed Capacity of  2075).

Total System Capacity: 4.565Kwh with an estimated output of 3287 KWh - total cost £5,727.56 including labour.

They are part of the MCS, RECC & NAPIT (have doubled checked on each of these sites for their membership).

I am awaiting a quote for how much extra it would cost to install Bird Mesh (Solar Skirt).

What's everyone's thought's on the above?

By my Calculation, assuming at 33.41 pence per KWh for electricity and using 38% of that produced, whilst exporting the remaining 62% at 15pence per Kwh, it will take 7.92 years to pay back the initial capital costs - £728 benefit a year.

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Incidentally, the quote for the Battery I probably won't go for, but it came in at £8585.48 (£2856.92 more vs. just Solar)

11 x Trina Vertex S 415W All Black Mono solar panel
GivEnergy 3.6kW hybrid inverter
Emlite ECA2 extended cover
Shine Lan - Growatt
GivEnergy 100A DC breaker
GEM-CT-45/100
GivEnergy WiFi Dongle
AC isolator - Projoy 20A 4-pole
GivEnergy 5.2kWh LiFePO4 Battery
IMO DC isolator 16A 2p 1string

Plus other required bits.

Assuming I was able to use 70% of my energy produced and exporting the remaining 30% at 15pence per Kwh, I've worked out that having the battery would benefit £969.99 - £246.99 more per year vs. Solar with no Battery - so would take 11.5 years to pay itself back.

This doesn't include benefitting from reduced electricity costs at nigh though which could add some additional benefits and bring the repayment period down.

However, my gut feeling is having a Battery at that cost just wouldn't be beneficial vs. keeping that extra £2856 in a bank account - especially as at only 5.4KWh it would be working very hard and likely would have a shortened life-span.

Screwdriva

ian1246 said:

However, my gut feeling is having a Battery at that cost just wouldn't be beneficial vs. keeping that extra £2856 in a bank account - especially as at only 5.4KWh it would be working very hard and likely would have a shortened life-span.

This is accurate (although the GivEnergy components are good and the incremental price is attractive).

That said, the quality of brands offered in the 1st quote, despite the low price, are bottom end bargain basement and are best avoided. (Here's Growatt's Trustpilot as a reference point)

An 11 panel SHARP system + optimizers + SolarEdge inverter should cost you £6500 including bird netting with a 20+ year warranty on everything. I'd recommend pursuing more quotes from installers willing to offer quality at the right price, not just the the latter. 

ian1246

Thanks for the feedback - I'm reasonably happy with the Solar Panels themselves (they have quite good reviews from what I can see online - a reasonable balance of cost vs. performance. vs. warranty period), but you are right - the Inverter looks awful. I'm waiting for a few more companies to come and give quotes - but one of the things I may do with the existing quote is go back to them and find out how much extra it will cost to replace the Inverter with the GivEnergy Hybrid one (which will open up the possibility of fitting a battery in the future).

Any other area's of concern I need to be aware of?