Your browser isn't supported
It looks like you're using an old web browser. To get the most out of the site and to ensure guides display correctly, we suggest upgrading your browser now. Download the latest:

Welcome to the MSE Forums

We're home to a fantastic community of MoneySavers but anyone can post. Please exercise caution & report spam, illegal, offensive or libellous posts/messages: click "report" or email forumteam@.

Search
  • FIRST POST
    • dan318064
    • By dan318064 28th Jun 18, 1:38 PM
    • 9Posts
    • 9Thanks
    dan318064
    Project Solar - am I getting ripped off? HELP!!
    • #1
    • 28th Jun 18, 1:38 PM
    Project Solar - am I getting ripped off? HELP!! 28th Jun 18 at 1:38 PM
    Hi

    I'm completely new to the forum world and also to solar power so am struggling with all the info I've been given. I have seen a LOT of threads on here about Project Solar and what a rip off they are so am treading very carefully but (surprise, surprise) the bloke we've been dealing with who surveyed the house etc seemed genuine (!) and has been very helpful in answering our queries and has offered a much lower price after some negotiation.

    As I say, I'm very new to this so their new offer could be cheaper than before but there are so many facts and figures that it's become too confusing to pick out whether it is really a good deal, which seems to be 2 words not associated with Project Solar!

    We have a flat roof on our loft conversion which can house 4 panels and can get south facing sun all day, it is 22msq. On our rear extension (its a standard Victorian terrace) we can get another 8 panels and this has a pitch of 40 degrees and faces South / South/West.


    I have to confess we haven't collected any other quotes as it has all happened quite quickly with Project Solar. We haven't signed anything and are willing to approach other companies but if this seems an ok quote we'd go with it.
    I suspect it may not be from the tone of every Project Solar thread on here!

    Please could anyone with a spare couple of minutes cast an eye over these figures and let us know if it seems reasonable or insane. If it's insane we'd welcome any suggestions and recommendations.

    Project Solar have offered us this:

    Core components 12 x SunPower solar panels Included
    12 x Tigo Optimized Included
    Battery Storage Included (Duracell)
    Social Energy Included
    Voltage optimiser Included
    Energy monitor: Solax monitor Included
    K2 mounting kit Included
    inc. access equipment (if required) Included
    Installation Fully installed Included
    Fully registered Included
    10 year workmanship warranty Included
    HIES warranty Included
    25 year performance guarantee on the output of the module Included
    Anti-theft device Included
    48 hour repair response with dedicated customer care Included
    Total cost of goods 10560.00
    Total cost of labour 2640.00
    Net total 13200
    VAT @ 5% 660.00
    Gross total 13860.00

    Standard Performance Estimation:
    Roof 1 kWp 4.00
    Roof 1 KK 827
    Roof 1 SF 0.83
    Roof 2 kWp 0.00
    Roof 2 KK 828
    Roof 2 SF 0.77
    Total kWh per annum 2745.64

    They have stated:

    Specification, assumptions & system output
    Number of panels 12
    Output wattage per panel 333.00
    System size (in kWp) 4.00
    Expected kWh 2745.64
    Current generation tariff 0.0393
    Current export tariff 0.0524
    Current unit price of electricity 0.1465
    Assumed rate of inflation (RPI) %3.04

    In summary of performance they and cost they have said this:

    Putting it all together
    Total income & savings in year 1 891.57
    Total generation tariff income over 20 years 47,47.73
    Total saving on electricity bill over 25 years 17,924.17
    Battery storage saving 2206.50
    Social Energy saving 10,750
    Voltage optimiser saving 7965.49
    Total savings from optional extras 20,921.99
    Total income & savings over 25 years 43,593.9
    Less cost of system (does not include finance charge) 13,860
    Estimated profit from scheme (does not include finance charge) 29,733.90
    Estimated payback time years 11 years
    Average return on investment over 25 years 12.58%

    We'd be covering this with finale which they have offered at 180 payments of 147.03 p/m at 9.9%

    REALLY sorry it is all facts and figures but we're hoping there is someone out there that can translate this into "yes, that's ok" or "Woah, don't touch it with a barge pole".

    Thanks so much for any feedback.

    Dan
Page 2
    • Martyn1981
    • By Martyn1981 6th Jul 18, 3:13 PM
    • 7,724 Posts
    • 12,295 Thanks
    Martyn1981
    Hiya Dan. I'm slightly confused (nothing new there). Does this install come with a 6.5kWh battery, or is it just 'battery ready'?

    With a battery it might be reasonable, but without it's pretty expensive.

    Your description of zero import in the sunny months, suggests a battery, and I would agree, that with a 5kWp system and 6.5kWh of battery, you would most likely import nothing, unless you use an awful lot of leccy. Just to be clear, if you had some really awful summer days of perhaps just 5kWh generation, then the batt might not carry you through, but that would be the exception not the rule, so let's caveat it with 'close to zero' import.

    The i-boost and boiler bit makes no sense to me, but perhaps it's something new ........ but ..... hmm.
    Mart. Cardiff. 5.58 kWp PV systems (3.58 ESE & 2.0 WNW)

    For general PV advice please see the PV FAQ thread on the Green & Ethical Board.
    • Zarch
    • By Zarch 6th Jul 18, 3:16 PM
    • 120 Posts
    • 278 Thanks
    Zarch
    The i-boost and boiler bit makes no sense to me, but perhaps it's something new ........ but ..... hmm.
    Originally posted by Martyn1981
    "Narrowing the pipes" bit concerned me..... !?!?

    As far as i'm aware, iBoost can't bring any benefits to a combi boiler system.

    https://www.marlec.co.uk/product/solar-iboost/?v=79cba1185463

    You need a water tank don't you?
    Last edited by Zarch; 06-07-2018 at 6:35 PM.
    • dan318064
    • By dan318064 6th Jul 18, 3:43 PM
    • 9 Posts
    • 9 Thanks
    dan318064
    Does this install come with a 6.5kWh battery, or is it just 'battery ready'?
    Yes, it comes with a 6.5K battery storage.
    • Martyn1981
    • By Martyn1981 6th Jul 18, 4:08 PM
    • 7,724 Posts
    • 12,295 Thanks
    Martyn1981
    Yes, it comes with a 6.5K battery storage.
    Originally posted by dan318064
    Apologies but I'm going to be really pedantic here. Is it 6.5kW, as I've been reading up and can see that their systems can charge discharge at 6kW, or is it 6.5kWh?

    The h is really important as kW is power, and kWh is energy. So the h means storage in this context.

    In which case 9k doesn't exactly sound cheap, but I don't think it's particularly expensive either with 310Wp Q cell panels, and 6.5kWh of storage.

    I assume the V-O Eco Max is some sort of voltage optimiser, so strip that and the i-boost out and suggest 8k .... perhaps?

    BTW - Certainly an interesting package, nice one to ponder that.
    Mart. Cardiff. 5.58 kWp PV systems (3.58 ESE & 2.0 WNW)

    For general PV advice please see the PV FAQ thread on the Green & Ethical Board.
    • pinnks
    • By pinnks 6th Jul 18, 4:47 PM
    • 663 Posts
    • 1,443 Thanks
    pinnks
    The iBoost has nothing to do with boiler control. It is just a clever switch, as are all other diverters. Mine is the immerSUN.

    They measure what is being generated v what is being used and push the rest out to a resistive load (immersion heater, underfloor heating, kettle, toaster, oil-filled radiators and the like). This way you maximise own use without risk of importing electricity to feed your, say, 3kW heating element. To work as designed for water heating you therefore need a tank with heater element.

    The immerSUN also has the ability to simply switch non-resistive loads on but that really is just a switch - when production passes a certain level something is switched on, irrespective of whether that would cause you to import electricity. This is really intended for low-power things like a destratification pump on your hot water tank. Not sure if the iBoost has such functionality. If it does I guess it could control a boiler but hardly the intended purpose or anything I have ever heard from the lips of those selling such devices...

    And the reference to narrowing pipes is complete nonsense and would make me wonder whether the whole quote is quite what it seems as 8+k for all of that is pretty good given the cost of batteries.

    Maybe have another read of that part of your quote and post a bit more info on the iBoost proposal here to let folks comment in a more informed manner?
    Wiltshire - 5.25kWp
    3.5kWp: 14 x Phono Solar 250 Onyx, Sunny Boy 4000TL, WSW 40 degrees, June 2013
    1.75kWp: 7 x Phono Solar 250 Onyx, Sunny Boy 1600TL, SSE 45 degrees, March 2014
    • dan318064
    • By dan318064 7th Jul 18, 9:14 AM
    • 9 Posts
    • 9 Thanks
    dan318064
    is it 6.5kWh?
    The h is really important as kW is power, and kWh is energy. So the h means storage in this context.
    Originally posted by Martyn1981
    My apologies, yes, there is the crucial h. I've just been emailed a proper quote and it states that the Battery Storage System Size 6.5KWH.
    • dan318064
    • By dan318064 7th Jul 18, 9:37 AM
    • 9 Posts
    • 9 Thanks
    dan318064
    And the reference to narrowing pipes is complete nonsense and would make me wonder whether the whole quote is quite what it seems as 8+k for all of that is pretty good given the cost of batteries.

    Maybe have another read of that part of your quote and post a bit more info on the iBoost proposal here to let folks comment in a more informed manner?
    Originally posted by pinnks
    You're right, the narrowing pipes thing is nonsense, that was me simplifying his explanation really badly. He said that the way the iBoost is designed it can work with a combi boiler by restricting the flow of energy in and out of the boiler. He said that combi boilers tend to use a far higher level of energy than they need and the iBoost can read that and restrict it down to the minimum level that it can still work at.
    really sorry, even that explanation is poor, but you know what its like when someone visits you for an hour and a half, bombards you with facts and figures (not my forte sadly) and then you try and dig out the gist of what they said after!

    He's emailed through the proper quote now, so I can list the elements correctly now.
    I'd be interested to know people's reaction.

    Do I need to reach for my barge pole again?!

    Solar Panels 16x 310W Q Cells-Q-PEAK DUO-G5
    Inverter 1x SolaX Hybrid Inverter SK-SU 5000E
    Voltage Optimiser Eco Max
    Hot Water Control I-Boost
    Generation Meter Yes
    Mounting Kit Yes
    Isolator Switches 4
    Cable & Connectors Yes
    Remote Monitoring Yes (SolaX online Monitoring)
    EPC yes
    DNO Application yes
    Battery Storage System ( SolaX Hybrid) SolaX LG Chem
    Solar PV System Size 5Kwh plus 19.3%
    Battery Storage System Size 6.5KWH

    Total 8,997

    Just as an aside, I am thinking of changing to an EV and as the system has an inverter in it he said that I would be able to run a charging point straight off it, which sounded a bonus.
    • Martyn1981
    • By Martyn1981 7th Jul 18, 10:06 AM
    • 7,724 Posts
    • 12,295 Thanks
    Martyn1981
    My apologies, yes, there is the crucial h. I've just been emailed a proper quote and it states that the Battery Storage System Size 6.5KWH.
    Originally posted by dan318064
    Cheers, that improves the deal a lot. Also 6.5kWh makes sense as that matches one of the LG battery packs that Solax suggests.

    Personal opinion here, and mostly from the gut, but that PV system with those panels would be good at 6k, and I suspect the battery adds about 3k.

    So that's a good start. Stripping off some unwanted baggage gives you a friendly opening to counter with 8k since there should be cost savings of doing the batt and PV at the same time.

    This does however depend on whether you want to spend ~3k on a battery, and if you'll be using any finance.

    Sorry to be unclear, but it's sort of a decent deal if that's what you want, or a bit expensive if you are being sold up.

    At least I've stopped being grumpy and negative!
    Mart. Cardiff. 5.58 kWp PV systems (3.58 ESE & 2.0 WNW)

    For general PV advice please see the PV FAQ thread on the Green & Ethical Board.
    • Martyn1981
    • By Martyn1981 7th Jul 18, 10:13 AM
    • 7,724 Posts
    • 12,295 Thanks
    Martyn1981
    Battery Storage System ( SolaX Hybrid) SolaX LG Chem
    Originally posted by dan318064
    Doh! I should have read on before posting.


    Just as an aside, I am thinking of changing to an EV and as the system has an inverter in it he said that I would be able to run a charging point straight off it, which sounded a bonus.
    Originally posted by dan318064
    Which has changed my mind about not suggesting something else.

    In that case, a larger battery might be justified? I was going to suggest the Tesla Powerwall II which has 13.5kWh useable, so you'd probably have enough spare to charge the car after allowing for household consumption. BTW, that's the charge the car a bit each day, not all in one go.

    The price is around 6k plus install and local permitting, but that's VAT at 20%, whilst you'd be at 5% if installed with PV, and the fitting costs/permitting* will already be in the existing quote.

    *As the PWII can discharge at more than 3.68kW it also needs DNO permission (I understand) but that'll be within the quote you already have, as it's mentioned.

    Just a thought?
    Mart. Cardiff. 5.58 kWp PV systems (3.58 ESE & 2.0 WNW)

    For general PV advice please see the PV FAQ thread on the Green & Ethical Board.
    • Zarch
    • By Zarch 7th Jul 18, 10:22 AM
    • 120 Posts
    • 278 Thanks
    Zarch
    Sounds like the battery is this...... https://www.cclcomponents.com/lg-chem-48v-resu-6-5kwh-lithium-battery?gclid=Cj0KCQjwyYHaBRDvARIsAHkAXcvDfGwIoW-_-oUVbQIwz3KtuPTmCwo07Po1nhuN2ht_s-PcagFU2sMaAlv2EALw_wcB

    As Martyn says, puts the Solar bits without battery around 6k.

    But still don't know why he's selling you a iBoost (300?) as you've got a Combi.
    Plus, i'm not convinced you'll see the benefit of the Eco Max (300?) thingy from what i've read either?

    Maybe get a quote without those? Think it might look ok after that?

    Has he provided FIT figures and usage calcs etc? How many years does it say it will take to break even?

    For 5kWh system without the battery and at a 5.5k install price i'd say around 9 to 10 years based on current FIT figures. Obviously, how much you consume of what you use may affect, but not by too much.
    Last edited by Zarch; 07-07-2018 at 1:35 PM.
    • dan318064
    • By dan318064 7th Jul 18, 7:46 PM
    • 9 Posts
    • 9 Thanks
    dan318064
    But still don't know why he's selling you a iBoost (300?) as you've got a Combi.
    Plus, i'm not convinced you'll see the benefit of the Eco Max (300?) thingy from what i've read either?
    Maybe get a quote without those? Think it might look ok after that?
    Has he provided FIT figures and usage calcs etc? How many years does it say it will take to break even?
    Originally posted by Zarch
    Ok, here we go. He's knocked off 500 for the removal of the voltage optimiser and given an explanation for the i-Boost.
    I'll admit slight ignorance of how this will work with a combi but maybe you guys can make sense of it. If it looks like a loose I'll ask him to remove that from the quote.

    I don't really know how these forums work but I hope it's ok using you as a soundboard? I don't really know enough about this as it's early days for us but I hope you don't mind me garnering your opinion as its been invaluable so far.

    So, I asked him about the i-Boost and if he could provided us with FIT figures and usage calcs, plus also how many years would it take for us to break even on our investment and this is his reply....


    Mains Supply - 240V AC 50Hz 1Ph
    Consumption - 3VA
    Switching Mode - Volt Free
    Switching Current - 3A
    Boiler Suitability - Single small domestic boiler
    Standard Equipment - Main Controller, Flow Sensor, Return Sensor, Mains Harness
    User Adjustments - Active/Bypass Switch
    Viewing Indications - Current Mode, Systems Temperatures


    Any feedback again appreciated.
    • dan318064
    • By dan318064 7th Jul 18, 7:50 PM
    • 9 Posts
    • 9 Thanks
    dan318064
    Has he provided FIT figures and usage calcs etc? How many years does it say it will take to break even?

    For 5kWh system without the battery and at a 5.5k install price i'd say around 9 to 10 years based on current FIT figures. Obviously, how much you consume of what you use may affect, but not by too much.
    Originally posted by Zarch
    Sorry, missed the crucial bit off!! He said:

    The system size will be 4.96 kwh we can actually say 5 kwh. (5000kwh) and 6.5kwh energy storage with our Q cell GEN5 panels theres a 19.3 performance increase to (5965Kwh), the hybrid DC system will add up to 50% more as the energy save to use at nights will add to your total generation . (5965kwh plus 50% 2982kwh added by battery system.

    Total system generation per annum is 8947kwh
    The current FIT rate is 3.96p per kwh and 4.91p per kwh export, I have attached fit cart. Export payment is deem at 50%.

    FIT PAYMENT 8947kwh @ 3.96p 354
    50% EXPORT PAYMENT 4473kwh@ 4.91p 219
    On a 5kwh solar pv system and 6.5kwh hybrid your annual FIT payment will be 573
    Your current electric usage is 9667kwh at 14.89p per kw (1,439 annually) the system will save you up to 65% of your electric 935

    SAVINGS AND FIT Payments annual 1,508 the margin of error is 7% of this total, savings and FIT Payment is 1,403
    We will take out the voltage Optimisation, Please find below information on the boiler minder.
    You will brake even on investment in year 6.




    BOILER MINDER INFO.

    The new Energy Minder Auto is a new generation domestic boiler controller that is designed to reduce the cost of running a domestic central heating system.
    Specially developed software provides a self-learning controller that regulates the firing cycle of the boiler to match demand without any user intervention. Any change in the boiler output temperature made by the user is automatically tracked and catered for by the Energy Minder Auto software.

    Electronic sensors fitted to the flow and return pipes of the boiler provide the controller with the data required to establish the central heating demand, including individual flow and return temperatures, user operating temperature and temperature response times. The system employs a unique algorithm which analyses this data and modifies the boiler firing cycle accordingly.

    The result is a domestic boiler controller that is self-adaptive, requires no commissioning, is simple to install and automatically responds to any seasonal adjustments made to the heating system by the user.

    Benefits include an increase in central heating system efficiency, reduced heating fuel consumption, reduced CO2 emissions and reduced heating fuel expenditure.

    Mains Supply - 240V AC 50Hz 1Ph
    Consumption - 3VA
    Switching Mode - Volt Free
    Switching Current - 3A
    Boiler Suitability - Single small domestic boiler
    Standard Equipment - Main Controller, Flow Sensor, Return Sensor, Mains Harness
    User Adjustments - Active/Bypass Switch
    Viewing Indications - Current Mode, Systems Temperatures
    • pinnks
    • By pinnks 7th Jul 18, 10:43 PM
    • 663 Posts
    • 1,443 Thanks
    pinnks
    Perhaps it's me but this all reads as confusing nonsense - sorry - and still makes me worry somewhat about the quoter's motives.

    First, a system has a certain size - Wp per panel times number of panels. The quote says 16 x 310 = 4,960Wp, so just under 5Kwp. This is not an indication of how much the system will actually generate and the concept of some 19.3 performance increase by a certain type of panel is frankly nonsense. A panel has a measured Wp and that is that. Some panels are more "efficient" but all that means is that you get more Wp for the physical size of the panel. So one panel may be rated at 250Wp while another panel of the same size might be 310Wp. Put 16 of one of those on your roof you get 4kWp; 16 of the others 4.96kWp.

    Also, suggesting battery storage will add to your generation is total twaddle. The panels will generate a certain amount and that will be used in one of three ways: Go into the battery for use later; be used now; or be exported to the grid. Your FiT payments are based on what comes off the roof, once it is converted into AC - nothing else can feature and if someone suggests differently they are either living on a different planet or worse!

    Your system is unlikely to generate the Wp in kWh. I have 5.25kWp and generate about 4,500kWh per year. I would suggest that you would generate a similar ratio but that depends on the orientation of the roof(s), pitch and shading. So, I would guess perhaps 4,000kWp per year would be reasonable but Mart and others will have more knowledge than me on that.

    So, based on 4,000kWh per year FiT income of about 160 per year plus export of perhaps 100 making 260 in total. Reckon on own consumption of perhaps 150 per year, plus whatever saving the battery would give you but that will be less than your current total consumption. I don't know but perhaps you could save 75% of current overall leccy costs (excluding the daily standing charge)? I see the quote suggest about 935 saving at 65%. Perhaps that is reasonable but add 260 total FiT to that and you are well south of their estimate.

    What they say about the iBoost is, in my opinion total rubbish. All these devices can do is power purely resistive loads as I mentioned before. Unless you have a hot water tank with immersion element a diverter will be a total waste of money.

    What is described as a boiler minder may or may not be an interesting product - I have never heard of the concept - but has nothing whatsoever to do with a PV system and nothing to do with an iBoost or similar device. You may or may not think the investment is worth it but can decide that separately to your decision about PV as they are mutually exclusive things.

    Although I am a fan of PV I cannot see that you would break even after 6 years unless we hit hyper-inflation and FiTs go sky-high. If you reckon with about 260 FiT plus 150 leccy saving without battery you have 410 per year to repay your investment. If you take the battery that could increase to about 1,100 but could be less. If you reckon with 1,000, then you at 9 plus years.

    But do you really guzzle nearly 10,000 units of electricity per year? The most we have used in the last 10 years was about 7,500kWh with old CRT TVs, set-top boxes, old fridges etc, tungsten lighting and so on. Now, with new devices, TVs, LED lighting, energy awareness and so on we are now down at about 3,000kWh per year of which we supply about half from our roof. So if we had a battery the most we could save would be about 1,600kWh at say 15p or 240 per year if the battery gave us everything all year round and that is not likely to happen. If we cleared 200 additional savings with a battery I would be happy. So, if others are right and the battery element is 3k, you would need 15 years to repay the battery part - ignoring the fact that the battery may need replacing after 10 years or so.

    So, I still have concerns about the quoter and their real motives if what you have copied/pasted is in context.

    Sorry if this sounds a bit like a rant, I am not getting at you but am beginning to wonder whether you need that barge pole to hand.
    Wiltshire - 5.25kWp
    3.5kWp: 14 x Phono Solar 250 Onyx, Sunny Boy 4000TL, WSW 40 degrees, June 2013
    1.75kWp: 7 x Phono Solar 250 Onyx, Sunny Boy 1600TL, SSE 45 degrees, March 2014
    • dan318064
    • By dan318064 8th Jul 18, 1:44 AM
    • 9 Posts
    • 9 Thanks
    dan318064
    But do you really guzzle nearly 10,000 units of electricity per year?
    Originally posted by pinnks
    Shamefully we do use almost that amount. Our leech bill from SSE last year showed an annual usage of 8,982.00kWh. All the PV installers that we have had over to quote so far have been shocked at that. To put it into context; we both work from home, I run computers 24hrs a day as I have contact backups going on through the night and am working on them during the day. I have e servers running 24/7 but this is something I need to address and change my working practice to match my ethics.

    To also aid any comments on how much the system may or may not generate I should probably put us on the map. We live in SE England (London) so have a relatively high amount of sunny days to help us along plus we have a loft conversion with a flat roof that is completely unobstructed by any trees or buildings shade wise. We are planning to have 8 panels on there.
    Our rear extension is south facing with the roof facing South / South/West with a pitch of 40 degrees with 5% shade . We're planning to have another 8 panels on there.
    I don't know whether this means we'll stand slightly m ore of a chance of attaining those kind of figures quoted but it seemed to make sense in pointing out that we should have a fairly good aspect for solar use.
    • Martyn1981
    • By Martyn1981 8th Jul 18, 8:37 AM
    • 7,724 Posts
    • 12,295 Thanks
    Martyn1981
    Like pinnks I have some negatives, but nothing against you. Also whilst I agree 100% with pinnks post, I think I can do a tiny bit of polishing now with your last post and roof data.

    Firstly, generation. London, south facing and 40d pitch is an excellent set up, so 1,000kWh/kWp might be doable, even 1,100 some years.

    Have a play with PVGIS (see PV FAQ's sec 5 (link in my auto sig)) and see what it says.

    I think 4,500kWh's pa will be reasonable, with 5,000 possible, and even 5,500 on a good year, but see what PVGIS says.

    Next, total gen, panel efficiency etc etc. As Pinnks has explained, higher panel efficiency simply means that 1kWp of panels will take up less roof space, but it is still 1kWp of panels. So the crucial figure is the total kWp on your roof, not the efficiency of those panels.

    Batts will not increase your generation, that's entirely false. In fact (boring bit here) they will lower your generation a tiny bit, as there will be a small amount of loss on the leccy that goes into then back out of the batts, and as this occurs before the FiT meter (TGM - total generation meter) then that will reduce what the TGM records:-

    EG [Just a made up example] 5,000kWh's of generation. 2,500kWh's gets used at the time of generation or gets exported because the batts are full, so the TGM 'sees' all 2,500kWh.

    2,500kWh's go into then back out of the battery, with a 10% loss (250kWhs), so when you draw down those units, the TGM will only 'see' 2,250kWh's.

    High leccy consumption - you've explained why, so that seems fine, and PV will therefore make a lot of sense, as the more you consume, the greater the returns. Hard to say if the batt will be value for money, but you are certainly one of the consumers best placed to try.

    So total income and savings.

    Let's say 4,500kWh's pa, just to prevent being overly optimistic and to allow for some batt losses:

    FiT 4,500 @ 3.93p/kWh = 176.85
    Export 4,500 @ 50% deemed @ 5.24p/kWh = 117.90
    Sub total 294.75. I think we can call that 300.

    Leccy savings, now these are tricky, but with high daily consumption you will use more and export less, and the batt will mean even less export, apart from great days like this summer when there may still be too much generation for the batts.

    So I'm going to stick my neck out and suggest 3,500kWh's or possibly more, of that 4,500kWhs.

    3,500 @ 14.89p/kWh = 521.15

    All in, somewhere around 800 pa?

    I'm actually a bit shocked at that, and have gone back to double check (Pinnks have I made a mistake, that seems extremely high?)

    If you can get closer still to 8k, then that's a 10yr payback. The PV should be good for 30+yrs, inverter less, so make sure you have a long (extended) warranty. The batt will presumably be good for 10yrs, and hopefully 20yrs, but I suspect a replacement in 10yrs+ will be far, far cheaper.

    I think it's looking reasonable, unless I've gone off track somewhere.
    Mart. Cardiff. 5.58 kWp PV systems (3.58 ESE & 2.0 WNW)

    For general PV advice please see the PV FAQ thread on the Green & Ethical Board.
    • Martyn1981
    • By Martyn1981 8th Jul 18, 8:44 AM
    • 7,724 Posts
    • 12,295 Thanks
    Martyn1981
    I don't really know how these forums work but I hope it's ok using you as a soundboard? I don't really know enough about this as it's early days for us but I hope you don't mind me garnering your opinion as its been invaluable so far.
    Originally posted by dan318064
    I've always assumed that that's exactly what these forums are for, especially given the money saving side.

    Also, we have all been in your position, knowing very little and asking for help and guidance (a virtual hand holding exercise), so we are just paying it forward.

    Keep asking, pondering and researching until you are comfortable with a decision be it a yes or no. And golden rule on here, particularly with PV, there are no stupid questions, it's new kit and tech to you, and you only learn by being open to discussion.
    Mart. Cardiff. 5.58 kWp PV systems (3.58 ESE & 2.0 WNW)

    For general PV advice please see the PV FAQ thread on the Green & Ethical Board.
    • EricMears
    • By EricMears 8th Jul 18, 9:14 AM
    • 2,363 Posts
    • 4,132 Thanks
    EricMears
    Have a play with PVGIS (see PV FAQ's sec 5 (link in my auto sig)) and see what it says.
    Originally posted by Martyn1981
    Since some of the panels will be on a flat roof and others on a sloping one, you'll need to run PVGIS twice - once for each set - then add the results together.

    And I too agree that some of the extras being offered would be a waste of time (and money !). Voltage optimisation is seldom appropriate in a domestic setting and any sort of power recovery to an immersion heater won't work unless you have an immersion heater. As for the boiler management software, unless he can explain it in simple language (without violating the Laws of Thermodynamics) then I'd assume it's another unnecessary addition. Stripping out those items would probably result in a reasonably competitive quote - but I'd still urge you to get another quote (or several) so that you really know just how competitive it is (or of course accept an alternative).
    N Derbyshire.
    4kwp S Facing 17.5deg slope (dormer roof).
    • pinnks
    • By pinnks 8th Jul 18, 1:27 PM
    • 663 Posts
    • 1,443 Thanks
    pinnks
    Mart,

    Much more accurate numbers than my tired brain wanted to work out last night and given the constant load from the servers I think you are right about potential savings.

    My brother runs a similar set-up but is not (yet) on PV and we have often chatted about his base load - yes, I know I'm "sad". While the servers guzzle a lot over a 24-hour period they are still "relatively" low power. Each one may only consume 200W but put 4 or 5 together you are still ending up with an extra 1kWh based load. A 5kWp system would easily cover that for a large part of the day and on any reasonable day between say March and October would also put a good amount into the batteries. How often would one get the hours of darkness provided fully from the batteries? Perhaps 80% of those March to October days? And over the remainder of the year virtually everything produced would be used directly or via the batteries.

    So, with a relatively high but constant baseload and batteries I think you might well be right to think 3,500kWh leccy savings and 520 per year.


    As you say, total per year then around 800. But that is still only half of the 1,500 projected by the quote - but I think we are probably all agreed that that is based on incorrect maths and assumptions.


    I would love to save that amount of import but would not like that high usage...
    Wiltshire - 5.25kWp
    3.5kWp: 14 x Phono Solar 250 Onyx, Sunny Boy 4000TL, WSW 40 degrees, June 2013
    1.75kWp: 7 x Phono Solar 250 Onyx, Sunny Boy 1600TL, SSE 45 degrees, March 2014
    • Martyn1981
    • By Martyn1981 8th Jul 18, 1:59 PM
    • 7,724 Posts
    • 12,295 Thanks
    Martyn1981
    Cheers pinnks, I was genuinely surprised at the 800 figure. All the steps seemed to make sense from A to B to C etc, but when I typed 800 my brain went 'no way!'

    I don't want to mislead by being overly optimistic, but I think the 800 should be near the bottom of the range, as generation might be a bit better, and export lower.

    Certainly shows where PV and storage can work, and viability might start to creep in.
    Mart. Cardiff. 5.58 kWp PV systems (3.58 ESE & 2.0 WNW)

    For general PV advice please see the PV FAQ thread on the Green & Ethical Board.
    • pinnks
    • By pinnks 8th Jul 18, 6:20 PM
    • 663 Posts
    • 1,443 Thanks
    pinnks
    Indeed.

    Out of interest for the OP, my generation yesterday was 30kWh (my max possible would be about 32). Diverted 3.5kWh to hot water; own consumption 5.5kWh; imported 2kWh and exported a whopping 21kWh.

    Compare that to 15 March this year which was a couple of kWh below expectations: generation 11.5kWh; diverted 6kWh (water and UFH); imported 5.5kWh; exported less than 1kWh

    And December 26th, bang on expectation: generation 4kWh; diverted 1.5kWh (water and UFH); imported 11kWh; exported 0.2kWh

    Whether these numbers help the OP is a good question but three random days, 2 of which are more typical for the time of year than our current super-PV-weather
    Wiltshire - 5.25kWp
    3.5kWp: 14 x Phono Solar 250 Onyx, Sunny Boy 4000TL, WSW 40 degrees, June 2013
    1.75kWp: 7 x Phono Solar 250 Onyx, Sunny Boy 1600TL, SSE 45 degrees, March 2014
Welcome to our new Forum!

Our aim is to save you money quickly and easily. We hope you like it!

Forum Team Contact us

Live Stats

3,734Posts Today

9,569Users online

Martin's Twitter