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Small scale PV (DIY)

  • 23-01-2019 1:13pm
    #1
    Registered Users Posts: 411 ✭✭ phester28


    I have a metal shed that points in the right direction for sun. I can only fit 2 panels on this roof due to a telegraph pole that cast a shadow from 11am on so I am using this shadow as my limit of usable roof space.


    so 2 1 x 1.67m panels around 300w each mounted on unistrut and fixed to the shed roof is my plan.



    The house has just got a new roof and its slate but even at that its the small area that faces the sun so might only get 3 panels up there in the future and its around 10 meters from the shed. (hopefully I'm wrong and can get the grant for say another 5 panels if it all works out as a hobby first)



    most inverters I looked at will not start up with only 2 panels. ( I would want a grid tie with 2 strings so that I can run my future location independently) So in total we are looking at a 2 string sub 2KW inverter



    Will a metal shed that gets damp and cold be an issue for the inverter? most are supposed to be IP65 rated but cant help but think that it would shorten the life of it.


«1

Comments

  • Moderators, Category Moderators, Motoring & Transport Moderators, Regional East Moderators Posts: 58,907 CMod ✭✭✭✭ unkel


    Inverter even outside is no problem provided it has IP65 rating, but I would avoid having it in full sun or exposed to driving rain

    I'd say it is too much to expect an inverter to work for you for just 2 panels, that will also work once you add another string of 3 panels though, but I could be wrong here.

    A Solis Mini 1500 can take 50-500V intake, so just 2 panels would make it work. It takes only one string though. If the orientation of the panels on your house is the same as the orientation of the panels on your shed, you can connect all of them up in series in the one string, making this inverter suitable for starting with just 2 panels and then extending.

    If you are thinking of going the subsidy / grant route, get a few quotes in. If it was me, and I was to start with a 2 panel system, I would go DIY to keep the costs to a minimum.

    "Wind is Ireland's oil" - An Taoiseach, 25/05/2022



  • Registered Users Posts: 411 ✭✭ phester28


    just looking at various options. I am confused that 300W + panels are around 170-200 euro but a 3kw package on some of the uk sites cost 5.5k.



    so 9 panels at retail 180 each and say 400 euro for the inverter (OK lets say 1k to allow for a higher price branding) Still brings that total to half the 5.5k

    The mounting system and wire must only be a few hundred. Say 500 euro at a total guess. Are shops just riding profit in packages.

    Sites checked were: https://24solar.uk/en/solar-cell-packages/3-kwp/
    https://www.cclcomponents.com/solar-products/grid-tied-inverters/single-phase-grid-tied-solar-inverters

    So far I have just honed in on mono panels 60 cells with 300w min power in a 1.67 x 1 meter size. All panels seem to offer 25 years guarantee and loading figures look the same. A Solis 4g inverter with as many 300w panels seems to be the way to go. Quoted parasitic load of inverters now appears to be better with <1w night time being quoted.


  • Moderators, Society & Culture Moderators Posts: 31,304 Mod ✭✭✭✭ Gumbo


    phester28 wrote: »
    just looking at various options. I am confused that 300W + panels are around 170-200 euro but a 3kw package on some of the uk sites cost 5.5k.



    so 9 panels at retail 180 each and say 400 euro for the inverter (OK lets say 1k to allow for a higher price branding) Still brings that total to half the 5.5k

    The mounting system and wire must only be a few hundred. Say 500 euro at a total guess. Are shops just riding profit in packages.

    Sites checked were: https://24solar.uk/en/solar-cell-packages/3-kwp/
    https://www.cclcomponents.com/solar-products/grid-tied-inverters/single-phase-grid-tied-solar-inverters

    So far I have just honed in on mono panels 60 cells with 300w min power in a 1.67 x 1 meter size. All panels seem to offer 25 years guarantee and loading figures look the same. A Solis 4g inverter with as many 300w panels seems to be the way to go. Quoted parasitic load of inverters now appears to be better with <1w night time being quoted.

    What about labour and scaffolding to get onto the roof 3 stories up?
    warranty and aftersales.

    Im sure we can all build a DIY system for cheaper, but in business, there's overheads.


  • Registered Users Posts: 411 ✭✭ phester28


    This is the purchase price of the kit not the kit fitted. If you go back to what I said I mentioned the shop and retail price. Not Fitted by contractors etc


  • Moderators, Category Moderators, Motoring & Transport Moderators, Regional East Moderators Posts: 58,907 CMod ✭✭✭✭ unkel


    phester28 wrote: »
    just looking at various options. I am confused that 300W + panels are around 170-200 euro but a 3kw package on some of the uk sites cost 5.5k.



    so 9 panels at retail 180 each and say 400 euro for the inverter (OK lets say 1k to allow for a higher price branding) Still brings that total to half the 5.5k

    The mounting system and wire must only be a few hundred. Say 500 euro at a total guess. Are shops just riding profit in packages.

    Sites checked were: https://24solar.uk/en/solar-cell-packages/3-kwp/
    https://www.cclcomponents.com/solar-products/grid-tied-inverters/single-phase-grid-tied-solar-inverters

    Looks like you just picked very expensive shops. Where you got the prices for the panels and the inverter, do those shops / sites not do packages?

    "Wind is Ireland's oil" - An Taoiseach, 25/05/2022



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  • Registered Users Posts: 411 ✭✭ phester28


    Found an irish supplier that has better kit prices. https://solartricity.ie

    Is there any good reason for not overspecing your inverter. I expect that I would allow at least another 2 panels worth of headroom on DC input.

    Does anyone have a good grasp of the regulations. I would have thought an AC isolator switch and DC isolator switch at the inverter location would suffice. The kits on the irish site have some fancy roof mounted AC sense DC disconnect. Very safe but also a point of failure IMO?

    Any thoughts in general


  • Moderators, Category Moderators, Motoring & Transport Moderators, Regional East Moderators Posts: 58,907 CMod ✭✭✭✭ unkel


    You have found yourself the best supplier in this country. Not only have they got decent prices, but they're also friendly and helpful and will assist you in picking parts to put together your kit for your particular circumstances.

    "Wind is Ireland's oil" - An Taoiseach, 25/05/2022



  • Registered Users Posts: 1,627 ✭✭✭ quentingargan


    phester28 wrote: »
    Found an irish supplier that has better kit prices. https://solartricity.ie

    Is there any good reason for not overspecing your inverter. I expect that I would allow at least another 2 panels worth of headroom on DC input.

    Does anyone have a good grasp of the regulations. I would have thought an AC isolator switch and DC isolator switch at the inverter location would suffice. The kits on the irish site have some fancy roof mounted AC sense DC disconnect. Very safe but also a point of failure IMO?

    Any thoughts in general
    The firefighter safety switch disconnects the DC from the panel when firefighters switch off the grid. It is mandatory under the grant, but not often used on DIY installs.

    Yes - it is another thing that can go wrong. Indeed in Australia, according to these folks, (and others) ironically there was an increase in solar related fires as a result of these switches. In some other regions, if you put the inverter in the loft, they are not required and this is widely adopted on new house-builds in Ireland.


  • Closed Accounts Posts: 3,364 ✭✭✭ rolion


    Let me ask you why do you want to for DIY route !?
    Is going to test your patience and lots of nerves /arguments with wife.
    Not saving big money but gives you the feeling of something that you did and you can understand the system.

    You need to manage the supplier equipment delivery, roof man days working/sick/not showing up and the electricians small job "only one hour but 2 hours driving".

    In relation to components, based on my experience, there are good equipment, premium equipment and suppliers equipment.
    If you go with premium, such as LG panels, you get the best on the market.
    If you go with suppliers equipment, you get whatever they have in stock and make the most margins on them, selling to you as being the best.

    Also, please do not forget the shipping cost as at some break point, you can lose more than you bargained.

    Have fun...


  • Registered Users Posts: 411 ✭✭ phester28


    The reason for looking at diy up to now is just to play with 2 panels on my metal shed roof. I am looking at my narrow oddly shaped roof and my tile counting and measuring means that I can only get another 2 panels maybe 3 if am not measuring correctly, and then the run back to the shed could be 10 meters.

    So its either a professional install if i can fit enough panels on site or just a play thing to take the base load of the house. At present solar city is my preferred supplier


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  • Closed Accounts Posts: 3,364 ✭✭✭ rolion


    I'm sure you will have a great fun and bigger challenges in deciding what's best for you.

    I just want to say that I did same mistake as you...got 2 panels and played with them. After getting all the figures, i wasn't able to use them in the new array as the ordered ones were different types … and … with only 2 panels, the inverter takes a minimum voltage just to start-up and warm the electronics inside.

    Get as much information you can...and good luck.


  • Registered Users Posts: 411 ✭✭ phester28


    Hi rolion,

    Can you expand on the panels were mismatched so that I can learn from it. I would look for 300w 60 cell mono panels.

    If I understand the panel rating correctly then most panels from the same category, cell number and wattage and tech will have almost identical voltage and current ratings.


  • Closed Accounts Posts: 3,364 ✭✭✭ rolion


    phester28 wrote: »
    Hi rolion,

    Can you expand on the panels were mismatched so that I can learn from it. I would look for 300w 60 cell mono panels.

    If I understand the panel rating correctly then most panels from the same category, cell number and wattage and tech will have almost identical voltage and current ratings.

    Well...good question and i hope you avoid the mistake.
    I bought two "no-name" 250W panels,hoping to play on angles,output,position and so on.
    Didnt know at the time about minimum power-up of the inverter,actually knew zero. You can't put in series different panels as that will break the maths.

    Then,after 12 months,when i comitted to buy,i went for LGs 300 / 330W,total different type of panels in relation to electrical parameters.
    Those two panels todays are covering kitchen roof and powers fans and lights in greenhouse...

    In your case,by the time you decide to move up or upgrade,those 2 (two) panels might not be available to purchase.


  • Registered Users Posts: 411 ✭✭ phester28


    maths wise from what I can find out from here https://solarpanelsvenue.com/mixing-solar-panels/ as long as the voltage and isc of the panel is the same it will have no effect. I assume batch or manufacturer to manufacturer there will be small differences and so in series it will only be as good as your weakest panel.

    I'm not sure if heating will have an effect with a mismatch?

    always a good quote:
    "The performance of the solar array is as strong as the performance of the weakest element. "


  • Closed Accounts Posts: 3,364 ✭✭✭ rolion


    phester28 wrote: »
    maths wise from what I can find out from here https://solarpanelsvenue.com/mixing-solar-panels/ as long as the voltage and isc of the panel is the same it will have no effect. I assume batch or manufacturer to manufacturer there will be small differences and so in series it will only be as good as your weakest panel.

    I'm not sure if heating will have an effect with a mismatch?

    always a good quote:
    "The performance of the solar array is as strong as the performance of the weakest element. "

    When i received my LGs,each had a paper sheet with a barcode associated to each panel.
    On that sheet,was individual tests, panel by panel for all the electrical parameters. Not sure if they tried to match identical panels for my delivery or just standard Quality Control.

    Heating ... Where ? We have one of the best climate for PVs...

    The quote makes sense everywhere... :)


  • Registered Users Posts: 411 ✭✭ phester28


    I was being purely speculative. Might a panel mismatch be similar to a partial shade on a panel. From what I've read a partial shade on any panel will cause localized heating of said cell and will cause premature death of the panel. I think diode bypass per sub string (within a panel) was a way to mitigate this but I've no idea what is implemented on various panels.


  • Closed Accounts Posts: 3,364 ✭✭✭ rolion


    phester28 wrote: »
    I was being purely speculative. Might a panel mismatch be similar to a partial shade on a panel. From what I've read a partial shade on any panel will cause localized heating of said cell and will cause premature death of the panel. I think diode bypass per sub string (within a panel) was a way to mitigate this but I've no idea what is implemented on various panels.

    For whole panel, i recommend this one H E R E


    Optimization is one of six functional covers that pairs with an integrated modular junction box base (TS4-O), with a retrofit/add-on base (TS4-R-O), or a Duo retrofit/add-on base (TS4-R-O-Duo). Design using unequal string lengths and mixed orientations. Install into shaded areas with a reduced setback ratio. Optimize only where needed with selective deployment.

    Shade and mismatch tolerance
    Maximized roof usage

    Enhanced energy yield
    Plus all the benefits of Safety and Monitoring

    Greater design flexibility


  • Registered Users Posts: 411 ✭✭ phester28


    I have read up on some optimizers, think I found a uk supplier for a panel module at a price point of 50 euro per unit. Not sure how much these units would cost.

    From what I've been able to find out if the current and voltages are very close on panels then the losses from a mismatch are small and the mppt will keep the power generation at an optimum level. So from what I've read a panel from various manufactures with the same number of cells and the same size wound in theory produce a very similar VOC and ISC

    Anyway I'm getting ahead of myself for someone that has no solar yet :)


  • Registered Users Posts: 1,627 ✭✭✭ Nedved85


    I wonder is is possible to install solar panels on a steel shed (Steeltech type)? I have a 5m x 3m shed with the long side of the shed facing south more or less, would this squeeze in 5 solar panels given that they are usually just under 1m wide?


  • Registered Users Posts: 411 ✭✭ phester28


    yes but if you want say 4 or 5 panels they are typically 1m x 1.67m. They may extend beyond the apex of the shed depending on how long the width x length of the south facing side is.


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  • Registered Users Posts: 1,627 ✭✭✭ quentingargan


    Bear in mind that the clamps usually require the panels to have a 2cm gap. You could easily get 2 over 2 in landscape format (on their sides) and possibly another one beside them in portrait, but it wouldn't look nice.

    On panel sizes, what actually happens is that as panels come off the production line they pass through a light box with 1000w/m2 of light and the production is measured - this is to produce a flash report certifying the output of the product. if the output is 300 to 304 watts, it goes onto the pallet of 300w panels, if it is 295 to 299watts, it goes onto the 295 watt pallet. And so forth. There are small quirks of the production process that make some panels produce more than others, even on the same production line.

    One of the claimed benefits of optimisers is that you will get that extra wattage. Also, the panels will degrade at slightly different rates over the years, and the optimisers prevent all of their production falling to the most degraded one. I think the benefit of this is quite small and would only use optimisers to deal with partial shading or mixed orientations.

    I would stick to optimisers that are "generic" and will work with any brand of inverter. Too many companies are vulnerable to collapsing in the 25 year life cycle of a panel to go for a system where the inverter and optimiser are matched and proprietary.


  • Registered Users Posts: 1,627 ✭✭✭ Nedved85


    Interesting, I think a dual landscape option with one in portrait would work actually. I would not mind the portrait one to be honest at that would be at the back of the garden / not really visible.

    Where could I go to figure out how much a 1.5 kWh system would produce over a year based in Cork. I have a pretty low electricity bill at the moment, using around 10kWh per day since I moved into a new build (Heat pump, A rated).

    I do have an electric car, but I charge mostly at work (That could change in the future - who know's).


  • Registered Users Posts: 1,627 ✭✭✭ Nedved85




  • Registered Users Posts: 411 ✭✭ phester28


    Been sitting in the wings for quite a while now. But I am wondering if my usage justifies a PV setup (without battery).

    My bills say that my total usage over 12 months is around 2200KWh.

    at a vat inclusive price of 20cent per kwh that is only 450pa. The rest of the bill is PSO etc so unavoidable.

    I wanted to see when or how much i use during solar hours but at present my owl is acting the maggot. I never used it before for logging and it is causing all sorts of issues. I dont even think that at less than 150W you can rely on the data but I digress.

    In a few days I will know the KWH I use daily between 8-4pm and so I should be able to size accordingly.

    I have east west options on the main roof but this would then need to be done professionally Dual string all pushing up the cost. But I have the possibility of 2 or 3 panels on my flat roof (east or south) extension using a ballast systems (would still tie it to the house wall).

    Is 8am to 4pm a reasonable time frame for solar in cork or is it more 10 to 3pm for 50% production.


  • Registered Users Posts: 411 ✭✭ phester28


    Been sitting in the wings for quite a while now. But I am wondering if my usage justifies a PV setup (without battery).

    My bills say that my total usage over 12 months is around 2200KWh. (and this tallies with my owl so far at 6kwh per day)

    at a vat inclusive price of 20cent per kwh that is only 450pa. The rest of the bill is PSO etc so unavoidable.

    I wanted to see when or how much i use during solar hours but at present my owl is acting the maggot. I never used it before for logging and it is causing all sorts of issues. I dont even think that at less than 150W you can rely on the data but I digress.

    In a few days I will know the KWH I use daily between 8-4pm and so I should be able to size accordingly.

    I have east west options on the main roof but this would then need to be done professionally Dual string all pushing up the cost. But I have the possibility of 2 or 3 panels on my flat roof (east or south) extension using a ballast systems (would still tie it to the house wall).

    Is 8am to 4pm a reasonable time frame for solar in cork or is it more 10 to 3pm for 50% production.


  • Closed Accounts Posts: 3,364 ✭✭✭ rolion


    Hi Phester28,

    Good questions to challenge your mind...and pocket ! ;)

    Based on your post,the consumption is very small to justify a PV system,at 6KWh per 24 hours.
    i mean,from a RoI point of view AND as you asked,if the PVs produces maxim output at lunch time and you are not in house to switch the appliance(s) to benefit the free energy,that investment is lost.


    Let's have few assumptions,that stands to be corrected by other users.
    For a lets say 2Kwp panels,that 6 x 330W and a 2.5Kw inverter (as a minimum investment and under your house and space position constraints) and a hot water diverter,that may make some sense in respect with production versus consumption (while you are not home). and, this only in few months over calendar year, lets say april to november,as after than very little production to create and to divert.

    My PVs are making random peak power,it does happily the base load of the house and diverts the exces to the hot water storage.


    To see a feedback to your timeframe Prod vs Consume query... the ideal curve is as below:

    479321.jpg


    Practical curve is anything like these ones:

    479322.jpg

    479323.jpg

    479324.jpg




    So hard to say what the is the best timeframe,even if you stay with the weather forecast in front of you...
    I have the owl myself and i found it a bit reliable but im using to confirm or contradict other monitoring / reporting systems. You know that they charge now for the dashboard online access ? May be that is your problem...

    My free public advise is use the owl for a while,get your numbers right and then analyse your budget. Cannot say how much it will be but based on your report,a 2Kw installed power should take care of the basic load and possbile divert a good amount to your hot water tank.
    Regarding return and financial,i guess we will never get these money back... but we are doing a change in good for our environment.


  • Registered Users Posts: 411 ✭✭ phester28


    My owl is an old one and does not need a portal (web access) its a cm160

    looks like 6kwh per day is a good indication of my usage regardless of me being home for the weekend or not.

    DeviceID timestamp Watts Cost CO2 DayTotalWatts DayTotalCost DayTotalCO2
    1 07/05/2019 07:00 193 0.037828002 0.088780001 851.9317 0.16697872 391.88858
    1 07/05/2019 08:00 177 0.034692001 0.081419997 1160.049 0.22736965 533.6225
    1 07/05/2019 17:00 209 0.040964004 0.096139997 7451.5645 1.4605014 3427.7197
    1 07/05/2019 18:00 209 0.040964004 0.096139997 7762.185 1.521381 3570.6052

    looking between 7am and 6pm today I used around 7kwh as the wife was using tumble drier washing machine etc (as of 8pm ive used 8.1KWH)

    I am wondering if there is any diy install such as https://www.pluginsolar.co.uk/?product=plug-in-solar-duo-500w-ground-mount-kit-2#tab-certification

    I have a SWA in the shed connected to a plug in my house that goes to a sub board. (all done by a sparky).

    I bet the ESB regulation is going to be a stumbling block as I could do 3 panels SSE on my flat roof easy but with that size a micro inverter might be a more cost effective approach?

    Ive seem some Iboost controllers cheap that could at some point help dump any excess into the immersion.


  • Closed Accounts Posts: 3,364 ✭✭✭ rolion


    phester28 wrote: »
    My owl is an old one and does not need a portal (web access) its a cm160

    looks like 6kwh per day is a good indication of my usage regardless of me being home for the weekend or not.

    DeviceID timestamp Watts Cost CO2 DayTotalWatts DayTotalCost DayTotalCO2
    1 07/05/2019 07:00 193 0.037828002 0.088780001 851.9317 0.16697872 391.88858
    1 07/05/2019 08:00 177 0.034692001 0.081419997 1160.049 0.22736965 533.6225
    1 07/05/2019 17:00 209 0.040964004 0.096139997 7451.5645 1.4605014 3427.7197
    1 07/05/2019 18:00 209 0.040964004 0.096139997 7762.185 1.521381 3570.6052

    looking between 7am and 6pm today I used around 7kwh as the wife was using tumble drier washing machine etc (as of 8pm ive used 8.1KWH)

    I am wondering if there is any diy install such as https://www.pluginsolar.co.uk/?product=plug-in-solar-duo-500w-ground-mount-kit-2#tab-certification

    I have a SWA in the shed connected to a plug in my house that goes to a sub board. (all done by a sparky).

    I bet the ESB regulation is going to be a stumbling block as I could do 3 panels SSE on my flat roof easy but with that size a micro inverter might be a more cost effective approach?

    Ive seem some Iboost controllers cheap that could at some point help dump any excess into the immersion.


    For a decent return,without a 1Kw installed power ,that's almost 4 x 330W panels, i will not get a diverter.Not enough juice to keep th ehouse and to divert.
    And get a small inverter that can be abused later if you get more panels.
    All above,entirely DIY doable...


  • Registered Users Posts: 411 ✭✭ phester28


    I got some prices for inverter only from a company
    DC isolator not required – as the only DC is the lead from the panel to the micro-inverter. The micro-inverters have MC4 plugs, see attached.
    Our understanding is that a Firefighter Safety Switch should not be required as the micro-inverters have rapid shutdown built in, in case of grid failure/AC disconnect

    Part code Description Price ex VAT
    BPE-MI-600-EU-IR BPE 2 Port Microinverter €149.50
    BPE-MI-1300-EU-IR BPE 4 Port Microinverter €234.00
    Has anyone gone the route of micro gen panel mount.

    From what I understand that would cut out the need for some of the extra isolators and wiring. The only down side I can find thus far is the monitoring would be extra.

    I am seeing the bottom price for a 1Kw flat roof install wired to a socket spur. Ac Isolator is the only requirement that I can find for this type of setup and it would make the number of external components a minimum.

    The only extras I can think of are flat roof mounts, panels, maybe mc4 crimp tool, DC cabling, and suitable external AC cable to connect to house through Isolated / fused spur.

    Anyone have any thoughts on this approach. These microinverters appear to have the IE- EN certification so that should not be an issue


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  • Registered Users Posts: 411 ✭✭ phester28


    Keeping my eye on ebay for an inverter for an east west config Dual MPPT.

    So far Al the following have on their respective sites certificates for Ireland,

    I probably wont be buying until I get a roofer here for another job and see how much he thinks for mounting rails etc and many panels I can fit (a) with the SEAI 500mm exclusion and (b) breaking the 500mm exclusion on the hip/valley.

    Just seeing what these go for on ebay

    Goodwe Solar PV Inverter GW3600UK
    Growatt 2500MTL
    ABB Power-One Aurora Pvi 3.0

    Has anyone a bad thing to say about any of the above.


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