Solar and battery solution ...or is there better?

Reed_Richards

bucksman said:

I really appreciate the input to this original post.  My plan, like so many, I believe, is to continue to charge the EV using cheaper electricity at night (with Eon, it's around 10p between midnight and 7 am) and at the same time to charge the battery and then use the stored power from the battery to run the house during the day.  We use around 8-10kwh on average daily (excluding EV charging) to run the house. Any solar will be used for the battery or to sell back to the grid. My research had indicated that the battery capacity should be increased, hence the x2 batteries.  Maybe some maths is required! Eon is offering at the moment around 15p for export. 

This is exactly what I have been doing since last October; access to a cheap overnight tariff is something of a game-changer when it comes to making the case for a battery.  I only have about 5.9 kWh of usable capacity and I am a heavy electricity user as I have an ASHP.  But when the sun comes out it tops up the battery so on a good day I use very little day-rate electricity.  At the moment my challenge is to work out in advance when it is going to be really sunning so I don't have to fully charge my battery overnight.    

bucksman

Reed_Richards said:

bucksman said:

I really appreciate the input to this original post.  My plan, like so many, I believe, is to continue to charge the EV using cheaper electricity at night (with Eon, it's around 10p between midnight and 7 am) and at the same time to charge the battery and then use the stored power from the battery to run the house during the day.  We use around 8-10kwh on average daily (excluding EV charging) to run the house. Any solar will be used for the battery or to sell back to the grid. My research had indicated that the battery capacity should be increased, hence the x2 batteries.  Maybe some maths is required! Eon is offering at the moment around 15p for export. 

This is exactly what I have been doing since last October; access to a cheap overnight tariff is something of a game-changer when it comes to making the case for a battery.  I only have about 5.9 kWh of usable capacity and I am a heavy electricity user as I have an ASHP.  But when the sun comes out it tops up the battery so on a good day I use very little day-rate electricity.  At the moment my challenge is to work out in advance when it is going to be really sunning so I don't have to fully charge my battery overnight.    

I am pleased it is working for you. Weather forecasting is an interesting issue to have! In hindsight would you have increased your battery storage?

Reed_Richards

bucksman said:
  

I am pleased it is working for you. Weather forecasting is an interesting issue to have! In hindsight would you have increased your battery storage?

Yes and no.  I got my battery + solar system in early 2019, just in time to get in before the demise of the Feed-in Tariff.  Batteries were a lot more expensive then and a dubious proposition as a pure investment but I wasn't paid anything for the electricity I actually exported so it seemed desirable to use as much as I possibly could.  And at that time my inverter software did not support timed charging from the mains.

Move on 5 years, I now can charge my battery from the mains, I have an EV and an EV-charging tariff (also Eon, as it happens).  I would certainly like to have more battery storage capacity but my inverter will only support another battery identical to the one I have.  So I could get another battery system with a dedicated inverter or I could wait until I can use my car battery to power my home (which isn't happening nearly as fast as I would like).  So far i have just waited but I really ought to cost what another battery plus inverter would be and whether I could make it pay.    

Solarchaser

I would say that it very much depends on your own circumstances. 

With your current usage I'd say you are right on the line of where battery storage would be beneficial. 
Unsurprisingly alot of the roi depends on your outlay.

If you were to use the example quoted earlier of a system costing £4k with under 4kwh of storage, I'm sure the roi would be a long journey.
These days £4k will get you 30kwh of storage, I'm thinking that may change those calculations somewhat. 

I've tried using the calculator that screwdriva has linked a few times to compare it to my actual bills /usage etc and it gives me nonsense.
Perhaps I'm not inputting something right, but I have tried several times, and each time it tells me my current bill is much more than double what it actually is.

5.5 years ago I added batteries to my system partly as a wee project, partly to see if I could save money and partly to increase marital harmony.

Let me quickly explain the last part.
If it's sunny and you run the washing machine, it's much cheaper, and so I would like the washing machine ran in the sunny times.
My lovely wife wants to run the washing machine whenever the **** she wants, and doesn't want to wait till it's sunny. This creates a little friction.
Batteries remove that friction.
I store the sun's energy and she uses it whenever she wants. Happy wife, happy life!

Back then, there was no real seg worth talking about, and very very few time of use tarriffs, so most of my saving was from storing solar power and using it through the evening. 
It worked very well, and I'm very happy I invested in batteries.

A few years ago TOU tarriffs became more accessible and so I charge from solar in the brighter months and from off peak in the darker months.

With my energy usage on a normal tarrif I'd be paying around £6k a year.
With batteries, solar and intelligent octopus I'm paying £1300 a year, that's quite a difference. 

Now with the 15p seg available, I have the possibility of buying in electricity at 7.5p and selling it at 15p, and so something like a 30kwh battery just used in that way could make you an extra £650 a year, that would be a pretty good roi for a £4k battery plus a £1k inverter no??

Solarchaser

Screwdriva said:

Qyburn said:

Screwdriva said:
... You will be paid for your export of surplus solar PV at around 22p/kWh

Are you assuming power is all exported during the peak time 16:00 to 19:00?

If 100% generation was exported during the 4-7pm window, one would earn ~25p per kWh. If 100% were exported outside of this window, ~16p per kWh. In reality, a blended rate of ~18p for export can be expected on Flux in Q2 '24. This often increases to well north of 20p per kWh, once self consumption is factored in.  

Just to comment on this point, if you did buy far more solar than you would use, either deliberately or because you were mis sold solar as many people were, with figures of 50% usage without batteries, then something like octopus Flux would probably be a good consideration also.

It wouldn't work for me personally,  as there are only 3 hours of cheap rate electricity vs the 6 hours on octopus intelligent, and I need the longer time for heating my hot water cylinders and charging my ev, but being able to export 21kwh at 25p a time every day is quite appealing.

I may even flirt with it in the summer months.

bucksman

Thank you for the interesting and thought-provoking comments here from my original thread.  The question still remains in the original post: is this a good deal - some posts elsewhere seriously favour the Sunsynk inverter/battery with others noting issues with the app/website and customer support.  Views would be appreciated. 

Solarchaser

Personally I can't comment on sunsync as I've never had one.
I can comment on lux, sofar and growatt as I've has all 3.
Lux and sofar I'd recommend, growatt I definitely wouldn't.

I think if you looked at your quote without batteries it should be around the £6k mark in my opinion, and that means you would be paying £3k for 10 kwh of batteries. 
It's not a terrible price, but it's not great either.

I would also say that normally a solar panel is a solar panel and make is irrelevant,  however jinko do appear to have a higher failure rate than any other brand, though some of it comes down to opinions, screwdriva highly recommends sharp panels, and they may be great, but I've worked in other industries where sharp is prolific, and having dealt with them and their failures I wouldn't touch them, ever.

Screwdriva

Solarchaser said:

screwdriva highly recommends sharp panels, and they may be great, but I've worked in other industries where sharp is prolific, and having dealt with them and their failures I wouldn't touch them, ever.

Just a minor correction. Screwdriva recommends these brands, in order of preference:

Panels: Solarwatt/ AEG/ Meyer Burger/ Panasonic/ Sunpower/ REC/ REA/ Hyundai/  Q-Cells/ Sharp/ Eurener (budget)

Inverters: SolarEdge/ Enphase/ Victron/ Fronius or SMA with extended warranties as part of the quote. 

Sharp are rare in that they offer a 25/30 year guarantee (vs. warranty) which means they will offer a replacement panel if the terms of the guarantee are breached, at a price that most can afford. (Jinko offers £20 per failed panel and nothing towards the cost of replacement if memory serves).

If it were my roof and budget was not a concern, Solarwatt, Meyer Burger or AEG panels would be my top 3 picks but they are over 2X the cost of Sharp, per panel. 

Qyburn

Screwdriva said:

Just a minor correction. Screwdriva recommends these brands, in order of preference:

Panels: Solarwatt/ AEG/ Meyer Burger/ Panasonic/ Sunpower/ REC/ REA/ Hyundai/  Q-Cells/ Sharp/ Eurener (budget) 

You must admit you do mention Sharp a lot, so it's interesting to see they're your second to last choice. If I read your comment correctly.

Also interesting that the two options our possible installer offered, Sunpower and Q-Cells, are both on your list above Sharp.

Screwdriva

Qyburn said:

You must admit you do mention Sharp a lot, so it's interesting to see they're your second to last choice. If I read your comment correctly.

Also interesting that the two options our possible installer offered, Sunpower and Q-Cells, are both on your list above Sharp.

Guilty as charged. Sharp is an excellent, pragmatic choice of panel (I have installed 6 Sharp bifacial panels on my roof). QCells, Sharp and Eurener allow the few ethical installers I use to compete (read: beat) with the Chinese owned brands on price, despite UK market flooding, while offering far better aftersales support and longevity. I have now helped with over 130 installations, of which 100+ include Sharp panels. Not a single Sharp panel failure to date. 

Sunpower Maxeon 6 and the upcoming Maxeon 7 panels (25% efficiency, confirmed by NREL) are a envy inducing, superb choice of panel but they are not inexpensive (as I'm sure you're aware).