An Easy Way to Track Your Solar Installation Payback 

Have the spreadsheets been updated yet?

@@davespilbrow Hi Dave, your message reminded me to sort this - now done. Please let me know if it doesn't work as expected 👍

You're most welcome, and thanks for this great feedback :-)

Hi Chas, thanks very much for the great feedback! :-)

Thanks! :-)

Hi Michael, thanks for your kind words - I'm not sure if I feel the year went quick or not. I feel it went slow - but actually from what I hear, that's a good thing - when you're occupied with lots of things, the days go quick but the years go slow - I think I'd rather have it that way round! ... alas I digress! I like the way you carry out the financial analysis!

You're very welcome - I appreciate you taking time to give me this feedback :-)

Hi Ian - my pleasure and all the best with your solar journey - you'll love every part of it! :-)

Thanks :-) This one was particularly difficult trying to make the spreadsheet screens look a bit slicker than me just manually navigating them!

Hi there Jack, that's fab to read about your adventures in monitoring your payback! And really great that my spreadsheet is of some use to you as part of that :-)

My pleasure, Adrian - and apologies the spreadsheet is not available yet - I'm having problems with my hosting provider :-(

@@GaryDoesSolar Not a problem, and many thanks for sorting this out. I started playing with the sheet this evening 🙏 👍👍

You're most welcome! Hope it does the business for you :-)

That's brilliant!

Hi Carl, thanks for your very kind words - it's so great to hear than my videos are well received :-) Now, on equipment pricing, I tend to stay away from that in my videos because it quickly dates them... but it's worth keeping an eye on social forums like this one, where pricing is discussed all the time: facebook.com/groups/2197329430289466 All the best with whatever you eventually decide upon!

Thanks Rob. I like your strategy around avoiding clipping. I should try something similar as I have DC Coupled batteries 👍🏻 Perhaps my latest video will get you thinking again about charging overnight?

Thanks for the very kind feedback, Mark. Now, others have suggested the same. The video and spreadsheet were really just about trying to work out the breakeven point - not to see if money was better spent elsewhere... but if others wanted to improve the spreadsheet, I'm publishing any updated spreadsheets folks send me here: garydoessolar.com/payback_spreadsheets/ :-)

Wow - that's so very kind of you - thank you! :-) I think you're going to enjoy using the various tariffs they offer!

You're most welcome, and great that you've modified the spreadsheet to better suit your situation :-) Yeah, same here on the export vs import!

Thanks, and this is great advice for people! :-)

Good point re gas. Where I struggle is putting a financial value on the gas saved - which depends on making a 'best guess' as to the real efficiency when using it (which in turn varies with lots of other factors like how heavily loaded the boiler is at any one time). Comparing the solar and gas power needed to heat my hot water cylinder given similar starting conditions the efficiency is approx. 50%, way below the nominal 90+% that a condensing boiler is supposed to have (because of lot of heat is used to heat the boiler itself, and circulating water - which leaks away afterwards). Any suggestions to refine this value calculation would be appreciated.

Thanks for your kind words about the video and also subscribing. I hope you're able to secure the credit required to get you started...

@@GaryDoesSolar Yes, I will consider it as soon I pay the rest of my house loan... 11 more years to go.

in some ways those money are comming out of the pockets of the poor that cant afford free electricity.. im not sure this makes us more rich as a community

Wow a VAT on electricity well make sure obviously to include that in any calculations yes whatever comes out of your bank account in a given time period based upon expected electricity rates plus obviously tax implications which can be complicated in the USA and elsewhere for a given situation

@@Hansen710in other ways the stimulated demand that removal of VAT creates in the economy gives the poor an opportunity to take a job or start a business to supply that demand, which puts money right back into their pocket - if they are willing and able.

That's a great point, and one that I now can't believe I didn't realise myself! Back to my spreadsheet I go... 😁

Interesting point!

Thanks, and yes, that's a good suggestion!

Also, if you have an EV you aren’t on a standard tariff anymore, so actually your savings might not be as fast. (I did some rough calculations and it added a few years on my payback)

In fact one thing you shouldn't do is think another battery stops me going flat in December and January and half my consumption being at peak 30p rate so it all costs 7.5p rate instead, perhaps saving £225 at that time of year, so payback time is 30 years so it's not worth getting another battery. How can that be when the payback time for the whole system including one battery is less than six years? In reality the payback time for the second battery is only two to three years because the system pays for it.

Thanks John for the great feedback, and also the detailed comments. I don't have an EV or a heat pump yet, but if I did, I'd likely want to factor in the fossil fuels that are not being consumed as a result. This would make for a slightly complicated spreadsheet, I guess...

Hi Rahul, thank you for your very kind words. I would love to see your spreadsheet and make it available to the community. Please feel free to email me@GaryDoesSolar.com - thank you!

Hi Mike, my apologies - I didn't see your comment here until now (sometimes RU-vid gets the notifications wrong). Please feel to email me@GaryDoesSolar.com with the latest version you have and if you're happy for me to, I'll upload it to here: garydoessolar.com/payback_spreadsheets/

Brilliant - thanks for sharing!

Thanks, and I think the way to handle the maintenance costs is simply to add those costs into the "capital expenditure" column as they occur.

You're very welcome, Graham. Funny you should mention about the NA() and " ". I originally had the latter, but then the chart flatlined where there was no data. Did you see the same?

@@GaryDoesSolar Yes Gary noticed that, now looking for and trying to understand articles on how to leave the chart blank as in the NA().

Cheers Joe - I'd love to hear how you get on with the comparison. Now, you're right about the EV and how to handle that. I'm of the mind that it should be kept as separate as possible, but I need to think about it more...

Thanks for the really great feedback. Now export is included as it's already accounted for in the bill payments you enter in column D. If you look at my own data towards the end of the video you'll see some of the entries in that column are negative (meaning export > import than month).

Hey Colin, that was some refund! And great news generally on the savings you're achieving - wow!

if you need to consider the lost initial interest, then you also need to consider the interest you earn from the lowered bills.

@@scottmcshannon6821That’s a really good point and something that should be considered. 🙏👍

I don't think it's insignificant. My purchase last march was funded from a maturing Cash isa and if I had reinvested I would have earned £600 in interest. So my £1440 in savings last year from solar is drastically reduced and my estimated 8yrs payback period increases to 13.8 years if I take lost interest into account. Obviously interest rates will vary but so will tariffs so its difficult to predict what will happen going forward. I can only look at last year's performance

Sounds great! Which country are you in?

​@@GaryDoesSolarI live in the UK, Essex. Interestingly, during the winter months the production was mostly the same on both the N and S facing panels and I assume this is because almost all the light is diffused indirect light due to the constant cloud cover.

@@NacNacMOTT Yes, when it is sunny then the north facing panels don't compare to the south facing ones. However since (in the UK anyway) most days are covered in cloud at some sky level: I find that most of the winter is generating power from indirect sunlight and generating mostly the same for N and S facing. Oh and yes, they are the same so I have 6Kw on both sides. For me, the added cost of the extra panels represented an extra 15-20% cost to the project but will deliver circa 60% more power which I'm most happy with.

@@NacNacMOTT I tend to find that I know more that most installers regardless of the topic mainly because I've researched it to death and I'm up to date on the knowledge. However the installer brings their massive value in how to actually put my paper-plans into reality (and if I'm really lucky they will bring some added value too to my paper plans).

You're most welcome. Now, I chose not to cover the FiT scheme as it was UK-only and now (as you say) discontinued. Those already on the scheme are enjoying lucrative benefits (great) but it's not open to anyone else. The scheme did its job though - it raised awareness to sustainable living with solar panels - pretty good result!

Wow - that's great to hear, James! And it's how things should work :-)

Thanks for sharing this, Gary. It's great to get a view of what's happening all over the world! :-)

That's brilliant - and will encourage those who are still on the fence!

I have to be quite strict with myself on what topics I cover. I don't have a lot of free time so I try and concentrate on the topics with widest appeal... Did you try searching for 48volt batteries on RU-vid?

@@GaryDoesSolar no problem m8, yeh iam even into solar myself but my job didnt start yet with battery installation but very interesting to learn all about it at least to give some good advice and answers to the customers.

Sounds like the volt was a great investment for you!

That sounds like you got a great deal there! Wishing you lots and lots of sun ☀️ 👍🏻

@@GaryDoesSolar kinda. I'm going to return the batteries. They are a weird type. LiFePO4 but 15 cells not 16, as far as I can tell. That makes them incompatible with every other LiFePO4 48v battery I'm aware of, since they are all 16. I've just found the fogstar ones which are 15kWh for the same price I paid for 10, so I'm going to get those instead.

You're very welcome. Now, you make a good point, but this video is really about those who have already made an investment into solar, providing an easy method for tracking the financial return on their investment. It was not intended to determine whether such an investment is better than other options. I'd be happy though for anyone who wants to enhance the spreadsheet, and I'll post any enhancements to it here: garydoessolar.com/payback_spreadsheets/

Thanks and yes, any additional costs should be added as part of the investment. When I asked my own home insurance company about any increase in premiums,they said there were none 👍🏻

It's true, you could benefit from tariffs like Agile without a solar and battery installation, but it would require careful management.

@@GaryDoesSolar agreed, although most people would probably be able to minimize their use during the peak period, and the Agile rates outside that are usually way lower than the fixed or "flexible" rates. But I agree that Agile comes into its own once you factor in solar/battery. The best return is when Octopus' run their saving sessions - charge the battery on the cheap, then discharge for the duration of the savings session, and they pay you the saving session reward for whatever you have exported. I made over £3 for one of these sessions on a single day...

With octopus 🐙 tariff you can export and import at a good rate if batteries are costly

Interesting point, and of course that value will change as the price of batteries continue to come down...

@@GaryDoesSolar surely batteries will be redundant unless you go off grid if the latest tariff by octopus makes good financial sense

@@GaryDoesSolar Indeed. That said, the main drivers of the return on investment for PV have always been primary household annual consumption, cost of components, followed by import and export tariffs. When you remove £3K of batteries (a rough minimum these days), a < 4k kWh p.a. consumption household experiences a ~2 year quicker break even point, more so if they have a West facing aspect to take advantage of Flux's peak export window, as your collab video data highlights.

Good point

Thanks Ian, and yes, column 2 does take that into account - you just enter the total of any and all import and export for the given month. See my own data near the end of the video, where I have entered negative numbers for some months given all the export I had...

Great stuff! :-)

im looking at a ROI in about a year and that incl. my crypto miners (that cost the same as my 16kw hybrid system).. adding some kaspa krypto miners for example can make the ROI many times faster... they also heat my house for free, its a win win i have a income of about 15000-30000€ a year on my solar and miners lots of ways to turn electricity into a product that is worth many times more then what the grid gives people... after all many companys makes money from using electricity getting stuff like heat as a waste product is also worth alot these days im not adding those savings, i easy use 2000€ to heat without my miners in a year

I was waiting for a smart meter but when I messaged them on X they responded immediately and fitted the smart meter within 2 weeks, they are quite responsive on social media. 👍

On the smart tariffs front, always read the fine print - the headlines may look good, but there are likely to be limitations.

I'll give you a counter to that - I moved to Octopus from EDF in mid March. I applied for smart meters as soon as my account was created. A few days later I was given dates to choose from for the meters to be fitted. This was a week before Easter so I chose the Tuesday morning after the bank holiday. Chap fitted them by 12pm and gave me a Home Mini rather than an IHD. I watched the feed for a few days and decided to move the Gas to Tracker. Applied on-line late in the afternoon on Monday this week, was sent an e-mail saying it was done on the Tuesday afternoon. I really can't complain about Octopus.

​@@GaryDoesSolarnot on Tracker or Agile

Thanks! I contacted Craig and he's updated the spreadsheet here: garydoessolar.com/payback_spreadsheets/ Could you try it please? Many thanks!

@@GaryDoesSolar Yes, that's sorted it. Good work. I do like the cross hairs. Now I just need some sunshine to match those pesky PVGIS estimates 🙂

Thanks 😀 For the video, I just looked at recent price cap data from Ofgem. There might be data here though for further back? energy-stats.uk/download-historical-pricing-data/

Hi Kent, that's great! We switched from a gas to an electric hob a couple of years ago and haven't looked back since. Easy to use and clean. And of course, can be powered by solar and battery most of the time! :-)

@@GaryDoesSolar I still have it as a backup and of course it is better than using a hob in certain circumstances but there is a massive difference in how much gas i've used and I would recommend having both options.

Oh my goodness! I bet your heart sank when you saw that immersion switch on (I know, I've been there myself!) Now, it might not affect things as much as you might think (maybe a 10-20% shift). What tariff are you on, and what sized battery?

​​​@@GaryDoesSolarI've been on Octopus Agile for about 6 months now - I watched the video and thought, 'Yes, I'm brave enough.' Currently, I've got 5 Pylon US2000's giving me a total of 12Kwh of which I've lost 2% over the year. After reviewing my log, my installer is suggesting increasing this to 16.8Kwh with 2 more batteries. It was more the fact that when Agile is free or negative, I've been force charging and also heating my water which will result in a lower gas usage which I'm not taking into account in the spreadsheet. But you think this may be negligible?

@@shaungilks8136 That's the great thing about a Pylontech array - you can just keep on adding to it - and pricing each time continues to fall 😃 It's hard for me to comment about the impact of your water heating impact...

Hi Paul, thanks for sharing this. I really don't understand your EPC rating. We recently had to get this done because we're looking at getting a heat pump. We got a straight "A" - specifically BECAUSE of the solar panels. Might be worth getting a second opinion?

Many thanks Gary for getting back, yes I think I will get another opinion. I did think about appealing to the company that did the survey but I very much doubt that they would overturn one of their employees decision.

That does NOT make sense to me. Solar should improve your EPC rating! I'd go back and question that.

Wow - great price and looks like a great return to go with it! :-)

@@GaryDoesSolar Bought direct, except the panels, which were bought locally at just over 100 euros a 450kw panel.

So, what we’re talking about here is asset value. Your solar and battery installation is also a depreciating asset as well as a revenue generator - very good point! 👍🏻

What I did was generate a report between two dates (the report option is near the bottom of the menu on the lefthand side. Then, when the report is ready, just scroll down to the section that I showed in the video. Message me if any issues...

I think I've worked it out watching again. It's just cost!! Great video still.

Thanks. Yeah, the standing charges should already be included in your actual bills 👍🏻

@@GaryDoesSolar OK so sorry trying not to be thick!!! The value in that box is the actual cost to INCLUDE the standing charge?

Yup, that’s correct. It’s the total amount that you pay the energy provider, standing charges included 👍🏻

@@GaryDoesSolar brilliant. Have you tried Predbat yet? Looking forward to a video on it. 😜

Thanks James - a Cosy video is on the list, certainly - I just need to get round to it! :-)

I have a utility for that here: garydoessolar.com/utilities/dailymodellingutility/ Enjoy!

What you get paid back vs what you are charged means it’s more likely to be better to consume the battery, this is one of the mains reasons for having a battery. You may also be able to buy cheaper off-peak electricity to charge your battery and use the battery during the day for those dark winter months.

Even better - I have a utility that might help, explained in this video: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-3G28AGyyrOU.html

Hi John, this could be handled with a couple of extra columns in the spreadsheet perhaps (turning the import rate column into peak, off-peak and percentage split. I don't have time to do this myself, but if anyone facies doing this, I'll add their work here: garydoessolar.com/payback_spreadsheets/

This could be handled with a couple of extra columns in the spreadsheet perhaps (turning the import rate column into peak, off-peak and percentage split. I don't have time to do this myself, but if anyone facies doing this, I'll add their work here: garydoessolar.com/payback_spreadsheets/

Tax rebates and other subsidies are necessary for starting up an industry. Few industries are self sustaining in their infancy. Once the industry “gets good”, the rebates can ease off. And then it becomes a tax revenue generator. Solar has been without subsidies in the uk for about 5 years now. One major advantage we have over the USA is a lack of local authority permitting paperwork. That’s a lot of cost saved. The only matters of paperwork that exist are with the electricity distribution companies for inverters connected to the grid that are bigger than 16Amps per phase. Even then the paperwork is generally free to submit.

Anthony provides great insight on your comment, Scott. I'd only add that the technology (solar panels, inverters, batteries) is getting cheaper all the time, which means more people and players will enter the market, which again will push prices down further. A virtuous cycle...

Unfortunately, l'm not in a position to provide individual advice (not least because of potential liability issues, even if that advice is given free - such is the world today). You're best to speak to an installer for such advice, or post a comment onto a solar forum (e.g. this one in the UK: facebook.com/groups/2197329430289466). Good luck!

Yeah,... depending on the price of the battery of course. But those prices are coming down a lot at the moment... :-)

@@GaryDoesSolar 🔋🥂

For the "with solar" it does, but remember that's already included in the bills you pay, yeah?

That’s correct 👍🏻

Try this: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-MdpQci4vTLU.html

I guess the problem is that most people in the country who don't have solar don't even know about the daily tracker tariffs... I'm targeting that audience too. I'm going to write a note about the financing...

Hi Lars, yeah, I think using estimates from the Octopus app would be ok, as will be omitting standing charges because essentially all they do is add height to both the green and red lines - they'll still cross at the time month/year. Yes, any income from saving sessions should go into the billing column. Great news about your savings progress so far!

I got octopus to change me to monthly billing as so much easier keeping a track on usage.

@@dlozuk I get billed monthly, just in the middle of it. Do you mean you got them to charge you at the end, like in a proper calendar?

@@larsmenken2679Great question - and I’d like to know the answer too! 😊

I honestly think that in time, energy will be near-zero pretty much all the time. Imagine what that does in enabling national economies - all of that energy cost taken out of the bottom lines.... golly!

Well, most people in the UK are on normal flexible tariffs unfortunately... They're not aware of the daily trackers...

You would not be unusual.

Depends which country you are in...

No, it is not just you. My hosting provider seems to be having a problem at the moment. I cannot upload the spreadsheet. Hopefully this will be resolved later today.

Good points, Derek, and thanks for your kind words. This video is about those who have already made an investment into solar, providing an easy method for tracking the financial return on their investment. It was not intended to determine whether such an investment is better than other options. I'll leave that to others...

@@GaryDoesSolar I quite agree with your need to keep things simple. So what follows is a PS, rather than a new comment... You said you'd leave the more complex analysis to others, so I've stepped into the breach and done a quick lash-up. Usually my Mac will read Excel spreadsheets, but I lost all the formulae in yours - the NA function was the issue. I put the formulae back in, and duplicated your first year's "example" figures into subsequent years. I reckon the break even point is Jan 28 (8 years). Then I surmised that if I had put the £10K installation cost into a cash ISA instead of buying solar, (moved to the pink column) I could generate about £33 a month in interest, which would reduce my non-solar electricity bill. I reckon the break-even point moved to almost 12 years. For people like myself - semi-retired - my installation cost has had to come from money put aside for monthly bills, so I do need to realise that my "true" breakeven point is quite a long way away, moreso because it takes the inverter and battery outside their warranty period. My "model" (to be fair) is overly simplified - it takes no account of inflation, which would mean my £33 a month reduced the non-solar bill by less and less, whereas a solar PV system is essentially inflation-proof and tax-free - can't get better than that!. In fact inflation-proofing my energy bills was a big point for me. Am I disappointed that my true breakeven point is so far in the future? Well no, because of something else one simply can't model.... We've moved to a village with underground mains supply, but the mains reaches the village on overhead wooden poles. In the most recent 12 months we have had 6 power cuts - 2 for maintenance and 4 for repairs. Although I'm semi-retired, my remaining work is teaching via video, so a power cut is a real emb*ggerance. But now my system switches over when there's a power-cut and everything in the house stays running. That's as valuable as inflation-proof energy bills! Thanks again for tackling an important consideration in the purchase of solar - may all your days be sunny ones!

@@DerekHasted Thanks very much for taking the time to do this, Derek. Very helpful to others 👍 And great to hear your system has made life a lot easier for you now, when there's a power cut.

This video is about those who have already made an investment into solar, providing an easy method for tracking the financial return on their investment. It was not intended to determine whether such an investment is better than other options. I'll leave that to others...

@@GaryDoesSolar Yeah so 4% interest rate, risk free (which is what most UK banks are offering at the moment) on £20,000 is £800 a year. So £2346 saving should actually be £1546, so estimated payback after 13 years, instead of the 8.5 years? To be fair, this does assume that the 4% will be around for the next decade which is certainly not guaranteed, so I can see it is still technically a risk.

Standard procedure for doing cost-benefit analysis.

It's the efficiency of your inverter when converting ac/dc results in heat

You're not wrong about solar panel prices - I'll be doing a video on the shortly. Prices are coming down like gravity! Regarding your generation question, what equipment do you have and what app are using?

@@GaryDoesSolar it is LuxPower about 800 kw out with the generation meter

Ah, I don’t know much about that battery, unfortunately. Might be worth asking a question of a solar forum like this one: facebook.com/groups/2197329430289466

The standing charge is already included with what you pay for your actual bills 👍🏻

So how can you show a bill for £0 for summer months in year one?

​@@clivehayball3782Maybe because even with standing charge, he's not using grid energy, and the export is more than covering SC etc?

That's the thing about Octopus - on some months I don't get a bill.

So £0 means no bill, not that savings exactly equals standing charge. Makes sense now.

I didn't have time to refine my sheet .... but I think it tells a tail

Thanks for sending me your spreadsheet. I would say it’s not a forgone conclusion that those without solar would be on a tracker tariff. Most of the population is on a fixed standard rate (and may not want the uncertainty of a tracker tariff). Also, as we’re looking at a long term payback period, there are no guarantees as to what will happen with tracker rates. I agree however, for those that would want to compare against that, your spreadsheet is useful. Are you happy for me to upload it onto the website so that others can try it?

@@GaryDoesSolar Gary Agree with your tracker tariff assertion. But there is little certainty in life at all :-) For us octopus compare now says that Agile is better for us! I suppose also there's a median position of buying just a battery and using Octopus Go that would really bring down the cost per KWh. But the battery would require buying I suppose my general point is that if someone, for instance myself, is doing a real comparison. They would have specified the solar system very carefully. Hopefully they would also think about getting a better deal on electric tariff than just the standard. So the right hand side of the spreadsheet [none solar] should be treated to be as good an "investment" as it could be also. I'm more than happy for you to upload it. There is an issue the interest per month column Y is strictly not correct...I just divided the annual interest by 12. I was very surprised at the outcome doing it this way try 5%

The investing the 20k into something else would have to earn enough to pay for the energy bill, the odds of buying shares or anything else for 20k and it pay 2k dividends a year is very unlikely, and then you have the benifit of it actually adding value to your property so if you where to sell your property you probably won't get the full 20k that you initial invested but you will get something back, I say probably as in a previous house we lived in I had installed a 13k solar system, got the benifits from it for 3 years and actually got the money back plus extra after property sold as the buyer was willing to pay extra as we showed a years worth of electricity bills and how cheap they where and that extra covered the initial installation costs before any goverment incentives. But I do agree with the point about financing for a solar system as the interest or "account keeping fees" that some institutions charge can really add up

@@J-P88 you can make money on electricity in many ways. companys all over the world do that in many many ways... i agree shares is not the way to go.. but if you convert the power the system makes (or the grid makes) into more money then the day price.. it can never go wrong... im producing many times more money from my crypto miners, then the grid gives ..(+ free heat) worse case scenario i heat my house for free with them, but that is only if the whole world crashes.. i still make money if the prices for what i make drops over 500% right now im looking at a ROI in under a year for both solar batteries and crypto miners.. and i dont pay a heat bill in scandinavia money is the best form of battery.. i rather have a stuffed wallet, then a full battery im looking at a income of 15.000-30.000 € per year on my 16kw system

​@@Goodkiwibloke true, that's if it is bought through finance,, and even then it's all about shopping around for best deals and what works for each individual if that's the path one has to take.

This video is about those who have already made an investment into solar, providing an easy method for tracking the financial return on their investment. It was not intended to determine whether such an investment is better than other options. I'll leave that to others...

@tristramsnowdon5256 But did you do just that a year ago then? Of course you didn’t - because you could not be sure the price of gold would rise. Get real please… The returns on a solar installation, whilst they may not be as high as other investments, are all but guaranteed.

You're right - and it's actually the reason I started this channel - to help people really understand what they were getting into (including financially) before taking the leap...

That was my brothers argument but it was easy to show that the amount you are saving on energy far outstrips the return on investment given the current energy crisis.

What you have also missed is Solar panels usually add value to a property, hypothetically you install a 14k solar system to your house, live in the house for X amount of years, get the benifits from Solar and then sell the house you will get some of that initial investment back, IF lucky like we where, the buyer actually ended up offering extra on the house once we showed how low our electricity bills had been for 3 years so much so that it covered the initial Solar installation cost. And you pay your electricity bill but all you have to show for it is the paper or the email the bill was sent on.

This video is about those who have already made an investment into solar, providing an easy method for tracking the financial return on their investment. It was not intended to determine whether such an investment is better than other options. I'll leave that to others...

I use a similar amount of electricity to you. I don't know where you're getting your predicted output from but my 6.1kWh East facing system generates about 6300 kWh/year. It cost less than £7500 in summer 2021, and includes 4.8kWh battery storage. I agree that an adjustment for investing the money should be added. This can be done by adding the investment return that has been lost to the monthly running costs in the spreadsheet. The estimated payback period provided by my installer was around 13 years, but with the price of electricity almost doubling since then, the payback period by my calculations will be around 8 years.

I can understand where you're coming from with thinking not to include the cost of the system in your payback. It is relevant to include because the idea of the spreadsheet is to see how much money you can save in the long run, and the cost of the system is a part of that equation and therefore must be included, even if you have written off the cost as irrelevant. As for investing the money... I think you're missing the point. Yes, you can absolutely invest the money that you would have spend on the solar installation instead, but that money would then be completely divorced from the problem. The question is essentailly "If I spend £X on a solar instillation, when will I have made my money back?" and not "Does installing solar make me the most money?".

@@Blocksetter63 I'm treating it as an investment therefore I have to compare it to a different investment. ie compound interest. I need a return in 10 years.... I'm 77 won't be in this house in 10 years. We're Southern Scotland that was the average output, well a little above average, of 4 quotes. My average quote was £11500 from memory. Not worth exporting far too little return. It's not worth the hassle though I'd love a system son that I can tell everyone I didn't need to pay for electricity this month I got it free from the roof. 🤣😔

@@varnect203 You either borrow the money in which case it's cost you more for the system. Or you use your savings in which case you would keep saving if you didn't go solar. Gary has also missed possible maintenance. Mine's a slate roof. We needed to replace a slate last year, I forget the cost maybe £200 . I asked the roofer what happens if a slate under PV panels needed to be replaced... Scaffolding, remove panel, replace slates, refit panels. £1500 to £2000

This video is about those who have already made an investment into solar, providing an easy method for tracking the financial return on their investment. It was not intended to determine whether such an investment is better than other options. I'll leave that to others...

Hi Jim, I think the spreadsheet does take that all into account, because you're entering the results of all that in terms of the (lower) bills you're paying. Quite a few have mentioned about investing with an ISA/fund instead. I'm going to write a note about that...

@@GaryDoesSolar Surely the "what you would have paid" figure needs to take into account overnight consumption x overnight tariff plus daily consumption x daily tariff? This is the "what you would have paid" calculation not what you actually paid. The difficulty is that if I hadn't installed Solar I wouldn't be charging battery overnight only the EV car, washing machine and tumble dryer so overnight consumption would be overstated (but I could subtract 5 kwh from each overnight figure as I charge fully overnight

The spreadsheet is really for those who have an installation now but were on a standard tariff before. For those who were already on some kind of smart tariff, the spreadsheet could be modified to suit (perhaps some will do that and send to me) but my videos are always aiming for the widest appeal.

@@GaryDoesSolar That would be interesting to see your thoughts. I have updated my own spreadsheet to take into account the 'loss' of interest by using capital to invest in Solar rather than for example continually re-investing in a simple Cash ISA. Based on the last 12 months figures (I installed at the end of March 2023) the data is telling me my payback is estimated at 7.7 years which is a lot better than my initial supplier proposal which suggested o payback of 9.5 years. HOWEVER I have effectively lost interest by not renewing my Cash ISA as the money to fund the installation was taken out of a maturing ISA so although it looks like I 'saved' c £1500 last year I didnt really as I could have made £580 in interest tax free ie I really only 'made' net £920. This reduction in estimated savings, which is significant, has a big impact on my payback period increasing it from 7.7 years to 12.6 years. I havent worried about compound interest, just considered simple interest ie removing the annual interest each year and leaving the principal amount (ie what I invested) in the ISA. I'm not actually that bothered tbh about length of payback as I consider the investment a sunk cost. Nobody worries about payback when they splash out on a new car, double glazing , a house extension or kitchen do they (although potentially an extension can increase the value of your house)!

@@jimgardner6394 I'm going to leave opportunity cost calculations to others, I think... 🙂

Have you tried bing.com - perhaps it has more recent imagery?

garydoessolar.com/payback_spreadsheets/

@@GaryDoesSolar I need to get on a PC to do this properly. It may be a few days as we are away from home. I absolutely hate Google sheets on a mobile phone 🙃

I'm hoping to get one soon, so can't wait!

Judging by the feedback to the video I've received so far, many people do wish to track things... Personally, I think it's a prudent thing to do (for any investment).

@@GaryDoesSolar it is prudent to do for any investment where you can adjust the factors. In this the only thing to do is optimise the benefit you have, manipulate your use and batteries to optimise your return. To truly calculate your ROI you would have to look at where the money would have been otherwise, the interest rates compounded or if the money was in a shares ISA then how the value of that changed including any dividends that would have been paid. Without doing that any returns measured are meaningless. It is worth looking at the expected return before purchase and along with the environmental factors decide if this is where you want your money to go. However, once installed it will do whatever it is going to do.

@@stephenrussell6074An ROI for a particular investment has nothing to do with an ROI of a different investment. It’s simply the return on that particular investment. My video was never about comparing investments, so I don’t know why you bring it up. That said, as you say, the payback on a solar investment will be what it will be. And my video provides an easy way to calculate such.

@@GaryDoesSolar if you are looking at the point where the solar panels have paid for themselves including additional amounts paid for repairs etc. then you have to consider the money not being spent on the panels at least being in a bank earning interest. In the same way that if you borrowed the money to invest in solar you would include the interest on the loan you had to pay. Likewise if you pulled the money out of an index linked ISA you have to consider the value that would have been if you had not purchased the Solar. Otherwise the so called ROI is not representative of anything. It is certainly not the point at which you begin to reap the rewards of your investment which is how the ROI is intended to work. I expect that everyone who borrows to buy will include the interest they pay as part of the cost. Likewise people who pull from their savings must also include those missed benefits otherwise the loan taker has a true ROI but the cash buyer does not. The reason for looking at it in any way can only be to affirm you made a good decision and it is no good doing that with a flawed end point. The cash buyer will probably have done better than the loan taker unless the loan was taken shortly before interest rates increased a lot. Which would also be impacted by price changes in the industry. My whole point is if you are going to make this calculation then it needs to be representative of the real situation at least the base of that case. Had nothing been done with the money. People who did or did not take a loan should have information that is roughly equivalent.

I think the advice you give on things to do before you buy a Solar generation system and how to use the tariffs and devices to optimise effectiveness are fantastic and a wonderful source of really useful information. However I see this exercise as not just pointless but also amongst the worst form of hubris since the time will reduce at the suffering of others. If Energy prices triple everyone suffers except this payback time drops dramatically whereas if they dropped to one third they may never payback within the life of the equipment.