I am in a similar situation and have the same question.
I contacted my installer but they are not being particularly helpful and wondering if a call to UKPN (in my case) is worth a try.
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Solar Panels UK - is it worth it?
- Thread starter jdwuk
- Start date
I contacted my installer but they are not being particularly helpful and wondering if a call to UKPN (in my case) is worth a try.
Thanks.Of late I've only used Microsoft SQL. That's expensive, but Microsoft has a freebie personal "Express SQL"
Almost certainly best that you stick with that then. its a solid product.
PostgreSQL has a good reputation - its free and open source (but I don't know whether that means that you can use it for absolutely free
I reckon one of those three will be your front runner. Have a look at the front end tools that you would use. Microsoft's SSMS is very comprehensive - given their pedigree for Program Languages / Tools, and maybe that makes it more worthwhile than the others (but MS is the only one I know)
Assuming you can get your data electronically I'd suggest start pulling that data regularly (scheduled) as a CSV/similar, even if you can't do anything with it for a bit, that would then give you some back historical data once your database is built. Maybe SmartMeter will let your download retrospectively?. Plus you have your own (much more granular) data from XLS. So get the data acquisition going, whilst you build the Database
I download data from my PowerWall which gives me Solar PV and House kWh consumption, as well as Charge / Discharge of the PowerWall (10 or 15 minute granularity from memory). SmartMeter probably makes similar available as a download.
I’ve got over a years worth of data from Bright/Glowmarkt so have some reasonably good data. What is Smartmeter, who offers that?
With the Powerwall data, is the only way to download it through the app?
ACarneiro
Active Member
Errrr.... You don't have a smart meter? Aren't you on Intelligent Octopus Go?
You'll need one in order to qualify for Octopus Outgoing, I think. It sends consumption data o your supplier every 30 minutes.
I have a smart meter. @WannabeOwner said ‘SmartMeter’ so I perhaps incorrectly assumed that was the name of an app or some software.
I use Home Assistant for more or less everything. It's pulling data from my inverter and from Octopus so it knows which rate I'm paying (including for Octopus Intelligent charging sessions) and then has one Energy Meter that total what I consume and another with what I import/export from the grid. I total these daily and work out the saving that I add to my running total.
Currently working out what I need to factor saving settings where I export as much as possible.
Currently working out what I need to factor saving settings where I export as much as possible.
WannabeOwner
Well-Known Member
WannabeOwner
Well-Known Member
Only way I know.
But if you set up automation, via the API, you could get it in real time. But I don't know if API lets you get historical data (so if your real time missed any then you'd have to faff about downloading and stitching the two together). I only use PowerWall data for "historical analysis" so I download it periodically, sat in front of the TV, and then import into database (along with same from Solcast)
I'm sure obvious (and if anyone has a better way speak up please!) but I go into APP and download (for each day in turn) and then "send" that to Dropbox ... and then download all-in-one-go from Dropbox to my PC - the CSV files are small, so Dropbox is a further backup of that data.
For Solcast I'm just using a Windows PC Scheduled task to pull the data at various times in the day (and storing it to accumulate a history of Forecast vs. Actual)
curl --header "Accept: text/csv" --output MyFileName_Actuals_yyyymmdd.CSV Solcast1234-5678-90ab-cdef/estimated_actuals?api_key=aB1cD2eF3gH4iJ5kL6mN7oP8qR9sT0uV
and
curl --header "Accept: text/csv" --output MyFileName_Forecast_yyyymmdd.CSV Solcast1234-5678-90ab-cdef/forecasts?api_key=aB1cD2eF3gH4iJ5kL6mN7oP8qR9sT0uV
Repeat if you have multiple Site Resource IDs with Solcast
Ever heard the phrase you cant teach an old dog new tricks? - I'm 68 - never heard of Database Programmer either, so not aware of perhaps better solutions to interrogate data, I've been with Excel from its inception, Indeed my dabbling's with computers predates the internet, I was into computers right from the ZX80, Texas Ti994a, Amiga 500 and there at the very start of bulletin boards - and super fast 1200bps noisy modems.
I've been retired now for 13 years - and when you finish work its surprisingly quick how all the drive and enthusiasm to maintain being "relevant" and abreast of new developments disappears into history. My life consists of only doing stuff when i want to, if i want to, its like a return to your childhood but with more money.
I've scratched my head quite a few times with Circular formula - a pain to track down the issue and hence why I say some of my formula could be better written especially where multiple calculations occur in a single cell - if it gets too hard for my brain i just separate the formula to individual cells - then hide what i don't need to see. I have worked with some real wizards on Excel - they achieve a more eloquent solution with a lot less brackets and equations and reliance on additional cells - but when i look at their formula I just cant follow it in my head - and with Excel you have to be able to relate every cell to the others to work out what's going on to find errors.
and yes - sometimes the issues seem too hard to fix, but you don't have a choice - apart from start again - which isn't really an option.
When you retire, nothing you do matters to anyone, in fact nothing that goes on in the world matters because the retired live in a separate universe, everything that occurs is between 10.00hrs (venturing out or starting to do something) and 1600hrs (time to get back home before the working population **** up the roads again)
WannabeOwner
Well-Known Member
My client was a relative young man at that time!
I mostly do that now ... well, not the bit about having "more money"
Excel has a button which will put arrows on cells to who where the formula goes. If you are not familiar with that then worth investigating if you have that problem in future. But, yeah, its still tedious to follow the arrows ... and then press the button again to get "more arrows" from that cell. Et al.
For that reason, even thought I am competent to do:
I don't. The next person that comes along who has to improve / sort it out won't be able to fathom it - including if that next person is me. Stick with your multiple-cells and simplified and more obvious formulae
Database code is a much better solution than XLS cell formulae. Much easier to see it "overall", and you don't have to have the exact same formula in a bunch of cells (waiting for something to come along and MOVE one or disrupt one by pasting over it etc. etc.)
The solutions our employees come up with, in XLS, are terrifying. Well beyond their competence. The only person in our organisation "safe" to use XLS is the Finance Director, as she has been properly trained etc. etc. But ... she is not a programmer, doesn't think like a programmer, so is not building her XLS to be "defensive" against things that may very well go wrong. Unlike other employees she is at least likely to do a Vertical Total and a Horizontal One and check they match, Whereas in CODE at least I can have "Is it YES" ... is it "NO" ... "Anything else? - Blow up"
=IF(A1="YES",1,IF(A1="NO",0,"********"))
is not a good alternative!! and hard to read - so-called "Write Only Code"
I download my Powerwall data from the Tesla API to a CSV file using this Powershell script and then reference the external CSV file from Excel (the Data > From Text/CSV command) and analyse/slice and dice it using PivotTables.
The Tesla API has historical data at 5 minute intervals so nice and granular, but that's still only about 100,000 rows per year so easy enough for Excel to chew through currently.
The Tesla API has historical data at 5 minute intervals so nice and granular, but that's still only about 100,000 rows per year so easy enough for Excel to chew through currently.
Pink Duck
Active Member
That does suffer from low precision compared to the Smart DCC and third-party apps (Loop Energy, Bright, etc.) giving kWh to 3 d.p. (nearest Watt-hour).
Drew57
Active ember
You should try volunteering with like minded of a similar vintage. It is like a return to your childhood but with varying degrees of decrepititude and forgetfulness laced with a heavy dose of black humour. Today our 32y old and employed 'teacher' said that we were an "absolute delight" (you may imagine the replies).
'Work' happens more by accident than design but when it does, the result is always in inverse proportion to the appearance of the purveyors.
(historic boat preservation, National Waterways Museum)
Pete UK
Member
Yeah,
I use my monthly kW usage from the bill and multiply it by 31p.
Then I subtract what I actually paid. Thats my
Savings. Job done.
20% VAT scrapped for storage
The UK government has exempted retrofitted battery energy storage systems (BESS) from its 20% VAT, from 1 February 2024.
www.current-news.co.uk
Although as one wag has already pointed out, manufacturer 20% price increase in 3....2.....1
Rooster6655
Active Member
I would just do it in a spreadsheet, when calculating the savings I would do them separate for the solar and battery like 2 entities then put them together at the end for the total savings. If charging the battery from the solar then I would count that as selling electric to the battery with the rate that I could charge the battery at night for for example. For a good comparison, I would also consider comparing to other tariffs such as the tracker etc, its a good way to get a true accurate calculation of what you are saving.
Pete UK
Member
Yes I do 7.5p.
I’m including that as a saving, compared to the (Octopus) SVR I was on pre Tesla and solar. Because that’s what I would be paying.
If I want to separate that and compare savings on the current IOG dual rate then I deduct the number of kW that went into the car and/ or house (using the car monthly data and octopus monthly bill data). All my consumption is at the cheap rate currently though so it’s fairly simple. But if it wasn’t I’d still deduct what I actually paid from the bill compared to actual kW usage (apportioned to peak rate and off-peak rate/ car/ house if necessary)
I’m also recording the daily solar production to give me a total/ maximum/ minimum and average for the month to compare it with my suppliers projection.
Initially I was doing this to monitor system performance and also to guestimate an overnight solar battery charge percentage target, but that has become redundant now post the 15p export rate. I just charge to full every night.
I’ve only got 5 and a half months of data so far though.
There is a bit of a spanner in the works due to how much of what I import gets exported that day. Thats variable; and in summer it’ll be all my solar exported and probably plus about 25-30kW of battery exported. How do you apportion that gain? Is it purely a battery or solar and battery saving, a car saving or a house saving? or is it more likely just a battery saving gain? Is it real usage or not? Yes and no.
For example: Say I import 38kW off-peak into the solar batteries and charge 12kW into the car but export 15kW later. What did I save that 15kW on? (30kW price equivalent). I effectively paid for 8kW off peak that day but did I save the rest on the car, the house or a mix? And what mix? And the solar that topped up the batteries, did that save me 7.5p /kW? gain me 7.5p/ kW (15-7.5) or save me 31p/kW of peak daily use?
And the savings sessions; Is that export from the overnight charge, the solar, or maybe a top up before the session or a mix of all of the above.
It’s all about how you think of it or apportion it -
but it’s all some kind of savings.
It can get pretty complicated very quickly.
I prefer to keep it as simple as possible. What I would have paid compared to what I actually paid. Personally I’m not sure I can justify the time or that I would significantly benefit myself by going really granular.
Although it is all very interesting.
The one thing I see from reading these comments regarding charging the home batteries at the cheap rate and exporting it at a higher rate thereby increasing the return is the number of cycles being introduced into the battery and the reduced life expectancy of the battery itself.
My Solax Triple power batteries are rated at 6000 cycles, (I have three 4.5Kwhr LI batteries) a cycle being from 10% to 100%, so a 50% charge is half a cycle, I charge them only from solar - so during the winter months there is little solar charge put into them and they seem to hover around the 10% mark - the cut off mark, 9 months of the year the solar and batteries pretty much run the house for free and the generation and Export FIT returns pretty much covers the 3 months where they generate little to nothing.
I could of course opt for whatever the equivalent is nowadays to economy 7 tariff and charge the batteries for a few pence per KWhr overnight and earn a bit more back from exporting that energy during the daytime, but each time you do that your introducing another cycle - which diminishes their lifespan.
What i don't know is the pure economics of it -If the return of those few additional pence is financially better than the cost of a shortened battery life.
The batteries were expensive £6K for the system with one 4.5Kwhr battery and a further £2K for each of the other two batteries - so £10K - this doesn't include the cost of the solar array/inverter/optimisers etc
I installed batteries for my own convenience and not to generate income and i suspect If I was to deploy the constant cheap charging of the batteries overnight and exporting during the daytime that the total income wouldn't compensate or cover the cost of early battery replacement.
I just don't know.
I had my system installed November 2018, The total cost was £14K, (I managed to acquire the additional two batteries which were £2K each for £1K each at the staff reduced price purchase scheme - I wasn't staff but the person i bought them from was) My spreadsheet total cost is based on the £14K figure and all saving are deducted as each month i put my meter reading into it. As of today my return of investment has been £6282.45 - so £7717.55 to go.
I estimate its going to be another 5 years to break even - so 10 years in total - and nowhere near the prediction that Solar and battery adverts lead you to believe by indicating ROI in 5 to 7 years.
I did opt for the best and most efficient system i could buy at the time (I could have saved £4K with a cheapo system) with the hope that it results in longevity and reliability, however, I expect that come the 10 year mark some equipment will be coming to the end of its life and further investment will be needed - like the battery inverter or perhaps a battery, panel optimisers. The panels themselves have 25 yr warranty - LG neon Rs and 20 years warranty on the main inverter - but the main cost items are covered by warranty and any further investment should be paid back pretty quickly.
All I really have to do is live long enough now.
My Solax Triple power batteries are rated at 6000 cycles, (I have three 4.5Kwhr LI batteries) a cycle being from 10% to 100%, so a 50% charge is half a cycle, I charge them only from solar - so during the winter months there is little solar charge put into them and they seem to hover around the 10% mark - the cut off mark, 9 months of the year the solar and batteries pretty much run the house for free and the generation and Export FIT returns pretty much covers the 3 months where they generate little to nothing.
I could of course opt for whatever the equivalent is nowadays to economy 7 tariff and charge the batteries for a few pence per KWhr overnight and earn a bit more back from exporting that energy during the daytime, but each time you do that your introducing another cycle - which diminishes their lifespan.
What i don't know is the pure economics of it -If the return of those few additional pence is financially better than the cost of a shortened battery life.
The batteries were expensive £6K for the system with one 4.5Kwhr battery and a further £2K for each of the other two batteries - so £10K - this doesn't include the cost of the solar array/inverter/optimisers etc
I installed batteries for my own convenience and not to generate income and i suspect If I was to deploy the constant cheap charging of the batteries overnight and exporting during the daytime that the total income wouldn't compensate or cover the cost of early battery replacement.
I just don't know.
I had my system installed November 2018, The total cost was £14K, (I managed to acquire the additional two batteries which were £2K each for £1K each at the staff reduced price purchase scheme - I wasn't staff but the person i bought them from was) My spreadsheet total cost is based on the £14K figure and all saving are deducted as each month i put my meter reading into it. As of today my return of investment has been £6282.45 - so £7717.55 to go.
I estimate its going to be another 5 years to break even - so 10 years in total - and nowhere near the prediction that Solar and battery adverts lead you to believe by indicating ROI in 5 to 7 years.
I did opt for the best and most efficient system i could buy at the time (I could have saved £4K with a cheapo system) with the hope that it results in longevity and reliability, however, I expect that come the 10 year mark some equipment will be coming to the end of its life and further investment will be needed - like the battery inverter or perhaps a battery, panel optimisers. The panels themselves have 25 yr warranty - LG neon Rs and 20 years warranty on the main inverter - but the main cost items are covered by warranty and any further investment should be paid back pretty quickly.
All I really have to do is live long enough now.
With a 10 year ROI and lets say a 20 year "solid" warranty, I dont think there is much to think about imho.
The future price of these things keep coming down in price as well so your ROI including the cost of inflation keeps going up. Yes you could tot up figures run graphs etc etc. but for some of us its the geek stuff, Isolating yourself for nasty spikes in energy costs and generally giving yourself a more predictable and comfortable way of living hence we dont get to tangled up with ROI's.
We will all live to 110 but some of us might wish they were dead before then
I've had cheap rate EV charging long before I got solar and battery, so I think for me I can't really claim that saving as part of my solar breakeven calculation. I couldn't see a way that was honest to myself without having some separate metering of consumption on and off peak to compare to actual import - export. For example today I've imported 86p of electricity overnight, but without the battery so far I would have spent £1 by now. that'll likely be about £4 by the end of the day.
