Hey @SallyWally27,

I’ll couple of our Solar members who can share their insight and opinions - @BPLightlog & @waltyboy.

Let me know if I can help with any questions 

We have had solar PV since 2012 and it has been a very useful investment. Obviously at that time the installation wasn’t via OVO but you should find some MCS registered installers locally to compare. 
I would also always recommend batteries as the solar generation never matches your usage and so it’s better to make use of all your solar power

Definitely worth doing.

Similarly to @BPLightlog I've had solar panels since 2013, a small array of nominally only 3kW, you’ll do much better nowadays with more productive panels plus being no longer limited to rooftop nominal solar capacity of around 3.6 kW (i.e. 16 Amps at house voltage of 230 volts): modern inverters can handle much larger solar capacity by being designed never to allow export of more than 16 Amps, balancing your home usage and, yes, recharging those crucial batteries in order to help do that.  My ancient and trustworthy Fronius IG has never faltered in over a decade of continuous use, but unlike modern versions isn’t up to that level of software sophistication! Mind you, up here in sunny Sunderland we rarely generate more than 1.3 or 1.4 kWh, even in mid June, and in Winter some (rare) days are zero.

HOWEVER, with the the addition of a very small 24 volt lithium battery a few years ago (nominally 2.4 kW) and a small additional inverter I found we can use every scrap of our low winter production of, say, 1 kW daily, because I use the battery exclusively to run everything in the house between 1600 hours and 0900 hours, recharging with an ordinary 24 volt charger between 0900 and darkness at 1600.  This is not the modern way, as a new system will be able to utilise cheap nighttime tariffs and help with your larger daytime usage, and so be more efficient.  As my wife and I are both retired we watch daytime consumption like hawks, and our evening and nighttime consumption averages only around 100 Wh (and that’s with a small chest freezer and a family-sized upright ‘fridge/freezer) just right for a 2.4 kWh battery so we buy perhaps half a penny’s worth of electricity from the grid hourly overnight. In the summer, of course, much of my rooftop production is exported (“wasted” from the point of view of our household, though not wasted of course in the larger community) because as BPLightlog says you can never use all of what you produce, but with batteries and a sharp eye you can go very close!
 

I would heartily recommend you to go ahead BUT with the usual caveats: seek expert advice, go for as much battery capacity as you can reasonably justify (somewhere between 5 and 15 kWh is normal nowadays, anything bigger requires some very serious thought). I take it you are UK customers of OVO? Our weather will not save you being reliant to some extent on the Grid.  But it’s the “some extent” that can be vastly tweaked with good planning. And then, if you are car drivers, there’s the whole EV side of things which with imaginative tariffs and possibly enabling household or grid usage of the EV’s own batteries (if one has one’s own drive, of course), over the next few years is going to make a panel/battery combo even more attractive (although remember EVs won’t charge solely from your panels without help if your rooftop is producing less than 6 Amps).
 

I would actually suggest that in the very near future, because of increasingly interesting tariffs, that a household battery is almost more relevant than solar panels! 

I can reassure you on one thing: after a decade or two of solar panels becoming ever more widespread in all parts of the UK there are no longer any myths or unanswered questions about productivity, the effect of differing annual solar irradiation figures in different parts of the Country, reliability of the kit, etc. etc. 

Good luck….and get good reputable advice, remember there’s no such thing as daft questions, only daft answers! But ultimately friends, neighbours, colleagues who already have solar panels are a good first port of call….plus the OVO forum of course!

Walt, thanks so much for your hugely helpful reply!

We are indeed Ovo customers, living in the PE7 postcode area (edge of East Anglia) so the weather is generally drier / brighter than many other areas. Roof shape / angle / orientation are near-perfect. We’re looking at a 9kW battery + 12x 440W panels from Ovo. Total electricity usage in 2023 was 7838kWh (= high, not least because my disabled husband and I are at home pretty much 24/7/365).

I am particularly interested to know if anyone has already used Ovo’s own solar setup service, recently promoted. It sounds well worth considering, and the incentives seem pretty generous – at least to begin with…!

I’ve not done very much research at all, yet I feel this is definitely the way to go – my gut is telling me so! If there are any genuine downsides (apart from the initial cost, which we are fortunate enough to be able to afford), I’d like to hear them.

Sally

Hi Sally, sounds like your envisaged system is a perfect size…hopefully someone with experience of the OVO Solar offerings will be along shortly.

You and your husband will have a lot of fun exploring the different options and making the final choice: and don’t worry, the process with a good firm is smooth and the disruption nowadays is minimal.

Initially, if you haven’t already done so, ask your local friendly electrician (who probably won’t be a solar installer) to come and have a quick initial look at your meter (is it a smart meter?), consumer unit and your house’s general electric set-up. S/he may well feel confident about pointing you in the direction of one or two local MCS installers who will then chat further about the physical logistics and structural requirements and options…the eventual chosen installer will also liaise with the grid supply people (your local DNO). 
 

All the very best, do let us know how you get on….

Hey @SallyWally27,

Wow, that’s some really good advice so far thanks to @waltyboy and @BPLightlog for sharing. If I can think of any of our members who’ve been through the OVO Solar journey then i’ll be sure to also tag them to come share some thoughts. 

This may also be of interest to you: 

As Walty has said please keep us updated and if there’s anything you aren’t sure of then please pop a question on and we can do our very best to make sure you get some advice. 

 I haven’t gone into any deep calculations about PV arrays and batteries, because I live in a rented property. The cottage has no gas, (inadequate) night storage heaters and an Economy 7 meter/wiring system, but because the NSH became so expensive to run a couple of years ago, I switched them off and switched to a single-rate tariff. I use other means to keep warm. Storing cheaper energy as heat doesn’t work well, but does storing it in batteries work any better?

I could do some sums to see what the return on investment would be for a battery installation designed to charge at the E7 night rate. I assume that it’s 100% efficient in that no energy is wasted (except perhaps in a hot Summer when the proportion that is ‘lost’ as heat would in fact be wasted), but I’m not sure how to determine the required battery specification. I’ve noticed a few recommendations (you know who you are!) to work out how much you think you need, then double it. The variables are:
 

Daily consumption. For the past year, this has been on average 2.800 kWh with considerable deviation. An Excel histogram shows that consumption is less than 3.0 kWh on 70% of days, less than 4.0 kWh on 83% of days and less than 5.0 kWh on 93% of days. Bearing in mind the advice of those who’ve been there, I’d probably say I should go for 5 kWh capacity.

Maximum draw. This is more problematic. Although the meter does register the momentary draw in kW, it doesn’t record it and I know of no way to capture it. It could be that @BPLightlog’s magic machinery could capture, say, the average draw over a minute or two, but that’s an awful lot of data to deal with. However, it would be necessary to go that granular when power-hungry devices may only be operating for a couple of minutes (kettle, toaster, for example). So I’d have to take an empirical approach and arrive at:

I suppose I could go down to 12 kW if I could guarantee that no-one would switch on the kettle while someone was in the shower. I’ve no idea how the system would react if that were to happen, though, and I haven’t looked to see if there is such an animal as a 5 kWh battery that would ever allow for a power draw of 12 kW.

Still, if I could charge the battery each night, consuming say 3 kWh on average, that would cost 3 x £0.1636 per day, or £180 p.a. On the equivalent single-rate tariff, the cost would be 2.8 x £0.2271 per day, or £232 p.a.  (rates from OVO’s E7 plans).

Saving of the order of £50 a year sounds like a 10-20 year payback period. However, a cheaper night rate (like some of those offered to EV owners) might make a much bigger difference.  Octopus’s 8.5p rate, for example, would save £90 a year, bringing the payback period down to perhaps 8 years, which I might just survive.

Do my sums make any sort of sense? Are there other considerations I haven’t taken into account?

The rule of thumb is to calculate a home energy battery to be around 90% efficient as it will lose power due to storage, losses in the inverter and other wiring resistances.

The daily requirements are one thing but you also need to consider solar generation calculations which are normally done by an installer but can be reviewed looking at panel orientation, declination/slope, shading from trees or other obstacles etc.

And those combined kW draws are critical as momentatary grid power will be used during times of excess (compared to the inverter/solar/battery capability). The other considerations are in terms of general daily cloud cover (which is why I make the point of battery need). Your appliances will draw the power they need and if necessary, the grid will supply as a balancing point in the whole scheme. This is why when some expect there to be no grid need, it never works out that way as the power switching of the inverter can be relatively slow, even with capacity in battery storage, for a few seconds.

Generally, you might expect a solar PV system to payback in something under 6 years. You would also get some sort of export payment on the SEG provision to add into the pot but most users with this type of set up would look to a TOU tariff which can easily drastically reduce any overnight charging costs required (during summer months, providing sufficient battery storage is installed, you would generally not need to charge from the grid at all).

And of course … you can never have too many batteries

Thanks, BP. I’m just not in the market for solar PV, sadly - that would be within the squire’s purview. A compact battery would in theory be portable, with a bit of judicious wiring, so I could take it with me if I were evicted.

I just had a quick look at prices for batteries. I’ve got a lot of rethinking to do ... 

@BPLightlog I’m interested in your comment regarding payback time:

“Generally, you might expect a solar PV system to payback in something under 6 years.”

I got a quote for a Solar + Battery system last year, and the payback time was between 12 and 13 years. A second quote came in at 8-9 years, using much cheaper gear that didn’t fill me with confidence. Needless to say, neither of these tempted me to go ahead!  

Nonetheless, I’m still interested and would love to know how 6 years is achievable, and with what hardware?

I will try to put some calculations together for you. My comment comes from my own experience of an installed system which cost around £8k and which paid back in under 8 years coupled with the current quotes I see for a G98 compliant system (3.6kw) costing between £5.5 and £6k.

My own tech uses a LuxPower inverter and Pylontech battery modules.

Whilst I appreciate that this isn’t specific enough, it is a reasonable assumption plus looking at increasing energy costs and therefore increased potential savings.

There are also individual factors to consider such as usage, location etc.

Thanks @BPLightlog  I’d appreciate that.

Interestingly, the quotes I had showed no difference in payback time between solar-only and solar + battery systems. By my analysis, that means the extra cost of the battery isn’t sufficiently offset by the saving in electricity consumption to be worth having…

Whilst I understand that calculation, battery storage in my view is vital to make the best use of solar PV (it never generates exactly when and what is required), plus battery storage allows increased flexibility in any grid usage meaning that time of use (ToU) tariffs can be targeted to give lower cost for any excess grid usage required. 

*This is a rough calculation and will not be valid in every case
If I take an example of an Ofgem ‘typical’ medium sized household consumption of 2900 kWh

at a ‘current’ rate of 20.6p per kWh cost would be approx £600 (excluding standing charges)

For a 3.6kw (G98) solar PV system I would expect around 3500 kWh of generation (shading, latitude etc obviously affects this)

I would expect solar PV + battery to cover at least 90% of usage. The remaining 10% usage from grid, with the flexibility of battery storage, can provide a further reduction in cost utilising a ToU tariff. This can result in a total annual cost of approx £12.50 (290 kWh @ 4.3p per kWh) plus standing charges. 
With battery storage, both excess generation and ‘phased’ charge/discharge cycles can be utilised. 
My own stats show export of around 1500kwh which can be redeemed at anything up to 20p per kWh. (I use 15p as that is my export tariff).

Additionally, with a ToU tariff, you can combine charge/discharge cycles which I approximate to 450 kWh. This technique allows charging ‘off peak’ at a variable rate (often negative cost) and exporting at standard rate (say 15p) which adds to the cost of savings. 
In the first year, this amounts to £910 in savings 

587 (reduction in usage) + 225 (general excess export) + 100 (charge/discharge cycles)

I have taken subsequent years at a 3% uplift but a 6 year total saving would then be £5900

As I mentioned at the top of this, there will be individual circumstances which affect this calculation but the calculations are from my own experience 

> I appreciate that this is a ‘best case’ scenario and also that ToU tariffs are not available from all providers. However, if someone is investing in solar PV and battery storage, it would seem sensible to make use of all potential advantages 

Hi @BPLightlog , thanks for taking the time and trouble to produce these detailed calcs. All very illuminating, from a variety of points of view.

Firstly, your calcs rely on something like Octopus Agile/Tracker to work, and assume significant time-shifting of consumption to extract the most economical performance - correct? I’m not sure I’m up for that level of engagement!

Secondly, your final 6-year figure of £5900 is interesting. The cheapest Solar + Battery quote I’ve had so far has been north of £10,500 - admittedly for a bigger (4.8kW) system than you are hypothesising. Are you really suggesting dropping the system size down to 3.6kW would halve the cost?

I have a new installer coming today to take a look at my place. It’ll be interesting to see how his figures come out.

I would be interested in any updates after your visitors @MikeyB .

I do use an Agile tariff as it provides the best value for anyone who can shift their major usage in a controlled way. It’s also much better for reducing emissions. I have recommended that OVO offer something similar but there is nothing currently available from them. 
I used a G98 (3.6kWh) system firstly as that is what my own system is based on and not everyone can get approval for a higher level. (G98 is fit and advise, G99 + is get approval before fitting and connection). If you can get approval for a higher level then it may well be worth it for the additional generation and potential export income. 
My own system is fairly automated to automatically charge at certain levels but I do occasionally initiate a manual charge/discharge cycle. 
Although I’m quite technically aware, I am approaching the ‘ancient’ level and so am not completely up to date on everything and of course I have not purchased a full system myself for over 10 years. The prices I quoted came from online research. 
I can confirm however that my own system was well worth the investment and I would recommend solar PV to anyone who can access it. 

I will indeed report back. The installer has gone away with all necessary info and a promise to be in touch shortly. He too was talking, unprompted by me,  of ‘aiming for’ 6 years payback time.

Last year my electricity bill, excluding standing charges, was about £820.

So, here’s my back-of-an-envelope calculation:

To achieve 6-years payback, assuming the system makes me 100% of my electricity, and I export say 2,000 kwH at 15p (ie £300 ‘income’), and assuming 3% per year increase in prices, the system needs to cost less than ((820+300)x6)x1.19 = £8025

Let’s see what unfolds...

Just another thought to add into the options .. there is the OVO Solar offer of course - there is a higher SEG return and what looks like a reasonable financial plan. 

Ah, I tried. They told me they won’t install panels on flat-roofed properties like mine unless I agree to a “full “ (ie expensive, messy, invasive, destructive) structural survey.  This was despite me making the design drawings and structural calculations available to them. Totally frustrating!

I also hit a brick wall with Octopus, who replied that they weren’t installing panels on flat-roofed properties “yet”, whatever that means.

The problem really is that these companies are using cheapo installers who just want to do the quick, easy, low-risk jobs - the low-hanging-fruit approach - and anything that might slow them down or cause them to have to think is just not worth the trouble to them.

I hadn’t picked up on that. The panels will need angled ‘platforms’ to mount on of course but it sounds like you’ve already considered that. 
I do know some who have used that option along with some additional support for wall mounted panels to extend their available area. Well your recent visitor sounded like they were up for it so hope you manage to get a suitable package. 

Well it’s taken a while, but I’ve now got a reasonable quote - I think.

6.45kW PV (15 *HTB* Longi HiMo6 Explorer 430W panels), 5.8kwH SolaX Triple 5.8kWh LFP battery, SolaX X1 G4 6.0D hybrid Inverter - £10,800 total cost.

Does that stack up? Comments welcome!

One immediate question I have is - during the winter, when the PV won’t generate much at all, I guess it makes sense to charge the battery overnight using cheaper off-peak electricity. But does OVO have a tariff or a bolt-on extra that allows this?

I’d say ‘well done’ on perseverance @MikeyB , that looks a decent system and being hybrid, it should be flexible should you want to add further battery capacity too. 
One thing unfortunately on the solar tariff is that I don’t know of one from OVO (that’s the main reason I switched). You are correct that moving towards winter, you should look to charge at ‘off peak’ rates (at least). Then the calculation is often, how much to charge which can depend on weather forecast, cloud cover, expected usage etc. 

One thing I would suggest is that you make sure that the installer shows you how to adjust settings via the app and also that you’re able to see generation, usage etc as we have seen several who don’t know how to access and operate the system.