Solar PV Advice Please

Chris_Wiseman

Hi all
Looking for a bit of solar advice. I’ve been investigating systems for a while but only got into our own house nine months ago and aware of the diminishing FIT incentives.

I own a large 3 bedroom house, relatively new build so good efficiency. I own a Nissan Leaf and home charge most days between 5-15kwh.

I’ve spoken to a few providers and have options from a local installer.
We have a main roof facing SE and a secondary garage roof facing SWW. We can fit 15 panels on the main roof and 6 on the garage roof.

I have approx. prices for systems as follows:
Just house - 4.5kw @ £5.4k (JA Solar) or 5.1kW @ £6.3k (LG 340)
Including garage – 5.46kw @ £5.5k (Perlight), 6.3kw @ £6.2k (JA Solar) or 7.14kW @ £7.6k (LG 340)

Wondering what is likely to work for us in terms of ROI. I have an expectation we will get a second EV within the next three years and I am also looking to add battery storage in the near to medium future when reasonable capacities become viable.

Any initial advice would be greatly appreciated.

Thanks

Chris

Martyn1981

Hiya and welcome.

First off, I think all those prices look good, so you're straight off to a nice start, not one of the folk coming on who've been quoted £12k for 4kWp .... or so.

Also, in my head, my fantasy PV system would be SE and SW, giving the best combination of good annual gen, good daily gen (throughout) and a good winter gen, so I'd certainly keep those WSW panels in the plan, especially as late afternoon demand is hard to avoid, such as cooking tea etc.

I think with a big system, and EV's, a big battery (10kWh+) is a great idea, but they are so expensive at the moment, quite frustrating.

Are you aware about DNO (distribution network operator) rules limiting output from the inverter(s) to 3.68kW without prior permission? As you are considering big systems, and they will overlap a lot with their generation profiles, you will really want to get permission for something in the 4-6kW region, depending on which package you finally go for.

So, initial advice/thoughts, you are on the right path, and look good.

Chris_Wiseman

Thanks for that Martyn, I'll have a chat with the installer re: DNO rules, but my initial thinking is to try and go as big as possible whilst keeping it economical.

Do you have any thoughts on the panels? The option with garage and JA Solar 300w panels seems to be the best option based on cost per KW and the potential to get ROI. The LG option taking it above 7kw would be nice but looks to me to be too much of a premium?

Thanks
Chris

Martyn1981

I think I'm with you on the economics, that the extra kWp is costing a bit too much. But, and this gets tricky to explain, but if you need, or can make use of that extra capacity and the generation it will provide, then you need to remember that revising it later won't be possible, or will cost a hell of a lot more.

But (again) with the small(!) system coming in at 6.3kWp and probably around 6,000kWh's pa, I'm not sure it matters so much whether you go super size. It would be far more important if you were considering 3kWp or 4kWp, not 6.3kWp or 7.14kWp ..... IYSWIM.

I think you are safe with all those options, but I'd massively favour the twin aspect solutions for that late afternoon generation, I added some a year later, which proportionately was much more expensive.

Zarch

Any shading to consider? Are these quotes for a Solar Edge based solution with power optimisers? Or are they putting the different aspects on separate strings?

Heedtheadvice

Just a small addition....


Given that you wish to charge cars then (unless it is in periods of low generation) you benefit a lot from having a system that generates much of that charge rather than buying off the grid i.e. at time you will charge your cars for free.


I understand the economic statement about the larger power installation but it might be worth considering those economics in light of what you would pay to charge your cars as well as home use and generation FIT and including that in your rate of return calculation.

butako

Hello,
Those are good prices, may I ask which company quoted them please? And where abouts in the country approximately? Thanks

Chris_Wiseman

Zarch wrote: »

Any shading to consider? Are these quotes for a Solar Edge based solution with power optimisers? Or are they putting the different aspects on separate strings?

No shading to consider - the SE facing roof is shade free until mid/late afternoon, the WSW facing roof remains shade free.

The quote is not based on Solar Edge, though I'm not sure it would add much based on this setup - thoughts?

The different aspects are remote from each other so they will be on seperate inverters. The garage is around 30m externally detached from house on a shared courtyard.

Thanks

Chris_Wiseman

butako wrote: »

Hello,
Those are good prices, may I ask which company quoted them please? And where abouts in the country approximately? Thanks

Bespoke Renewable Solutions - I'm based in Leicestershire

Chris_Wiseman

Heedtheadvice wrote: »

Just a small addition....


Given that you wish to charge cars then (unless it is in periods of low generation) you benefit a lot from having a system that generates much of that charge rather than buying off the grid i.e. at time you will charge your cars for free.


I understand the economic statement about the larger power installation but it might be worth considering those economics in light of what you would pay to charge your cars as well as home use and generation FIT and including that in your rate of return calculation.

Thanks for this. At the moment, we'll benefit mostly at weekends and a contribution late afternoon with the EV, due to working hours. When we move to being a two EV household, this will change in favour of more charging taking place earlier in the day.

For this reason I've been focusing on worst case for returns - FIT income. Then factoring in current use without future electricity price increases. Any usage saved above this, increases in energy prices saved and potential savings from battery storage slightly further down the line are all bonuses in my view.

In the short-term, have people seen good returns from solar diverters?

Thanks
Chris

Coastalwatch

Chris_Wiseman wrote: »

Thanks for this. At the moment, we'll benefit mostly at weekends and a contribution late afternoon with the EV, due to working hours. When we move to being a two EV household, this will change in favour of more charging taking place earlier in the day.

For this reason I've been focusing on worst case for returns - FIT income. Then factoring in current use without future electricity price increases. Any usage saved above this, increases in energy prices saved and potential savings from battery storage slightly further down the line are all bonuses in my view.

In the short-term, have people seen good returns from solar diverters?

Thanks
Chris

Hi Chris, I've followed your thread with interest but, being a newby to Solar panel installation haven't been able to offer any sound advice above that already posted.

I'm not sure what you mean by "Solar diverters" but if it is the system in general then we seem to have a lot in common!

Like you when trying to work out an ROI, I ignored any future potentional price increases focusing solely on what is known today. With thanks to the advice received on here we had installed the largest array our property would take which worked out to be 8.85 kWp and haven't regretted for one minute doing so. As for ROI, the forecast was 14.3 years when giving the go ahead in April.

We purchased a Nissan Leaf in July and had a Zappi installed to charge it from. As you say getting "free" lecky for this and adding battery storage at a later date for further savings are all bonuses. We've not regretted for one minute taking the plunge as, for us it was the only sensible way forward into the future. Without fit and export payments we couldn't have made a case for it, similarly if you have to borrow in order to allow it to happen then you will possibly have additional calculations to make! Putting it into perspective, if you invested £6 or £7k pounds in a bank or building society today you'd be lucky to see it doubled(ROI) in thirty years!
By coincidence our system just passed the 6 MWh's since installation. As we all know it's been something of an amazing summer and not typical of what to expect in future but the fit & export payments will total something very close to 4% of our initial investment.