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PV- real world figures

  • 03-09-2017 7:59pm
    #1
    denismc
    Registered Users Posts: 1,380 ✭✭✭


    I have been watching the price of domestic PV systems fall over the last number of years and I am now considering installing some in my home.

    There is a lot of information on the internet which is useful but I would like to hear from people who have installed domestic PV systems in the last few years.
    So if people could describe their system a little bit and maybe let us know if they found it to be a good investment i.e did it reduce your electric bill?

    Thanks


«13456

Comments

  • #2
    rolion
    Closed Accounts Posts: 3,362 ✭✭✭rolion


    denismc wrote: »
    I have been watching the price of domestic PV systems fall over the last number of years and I am now considering installing some in my home.

    There is a lot of information on the internet which is useful ....

    Not been labelled a smartie... but did you read any of the topics here !?
    What do you think ?


  • #3
    denismc
    Registered Users Posts: 1,380 ✭✭✭denismc


    rolion wrote: »
    Not been labelled a smartie... but did you read any of the topics here !?
    What do you think ?
    Yes I did, Did you read my post?


  • #4
    unkel
    Registered Users Posts: 64,693 ✭✭✭✭unkel


    denismc wrote: »
    Yes I did

    Did you really?

    Just read rolion's thread about his PV install. This thread has been on the first page of this forum for a very long time. It will give you all the answers your are looking for.

    And a short answer: of course it will reduce your electricity bill. But the return on investment is extremely poor. Many decades.


  • #5
    denismc
    Registered Users Posts: 1,380 ✭✭✭denismc


    Ok
    Apologies if I sounded a bit snotty.
    I did read that thread and while its very helpful, I am not an engineer. That thread is about a self built system and involves microgeneration and selling back to the grid. Some of this stuff might be straight forward to you guys but a lot of people searching this forum are not hobbyists but are looking for more of a standard installation.

    I suppose what I am trying to get at is having a thread where people can see peoples net savings over a year or multiple years.


  • #6
    unkel
    Registered Users Posts: 64,693 ✭✭✭✭unkel


    I'm like you, Denis. I would only look into a system that is fully installed for me. The unfortunate news is that you will save a few hundred but it will cost you many thousand. Solar PV is at the moment the last thing you should focus on.

    If you want to be green and want to save money, buy yourself an electric car. Massive savings to be had. And if your household uses lots and lots of hot water, get a solar tube hot water system installed.


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  • #7
    noel100
    Registered Users Posts: 358 ✭✭noel100


    I am looking at 5kw system for €2600
    Extra is the racking system for the roof
    And abour €400 euro delivery from UK

    18 x JAM6-K-BK-60-280-4BB-F35 JA Solar 280W Mono SK All Black 35mm

    1 x SOL-5.0-4G-DT Solis 5.0kW 4G Dual MPPT - Single Phase

    Should produce 5370kw electricity per year in midlands at optimal direction and angle.

    If you can use the 5370 units at 0.16kw
    Would equal €859 a year so should be paid off in 5-6years allowing for extras (electrician + cert) and a smart meter etc.


  • #8
    freddyuk
    Registered Users Posts: 1,110 ✭✭✭freddyuk


    You do not need a 5kw inverter for 5kwp of PV input and you do not need twin MPPT unless you need to avoid shading or have different aspect roofs. Normally inverter is 80% of total installed capacity because you rarely exceed the limits of the system and even then only briefly so not economic and inverters are more efficient running at near capacity. Keep the money towards a replacement inverter in 5-10 years possibly.
    You do not need a smart meter which is very expensive unless you are being paid for export which you will not be. Just have a generation meter to measure your total input.
    You will not use 100% of your generation so you need to have a diversion system to maximise on site usage as export is freely given away.
    PM me if you want help with UK supply as shipping racking systems is not viable !!


  • #9
    unkel
    Registered Users Posts: 64,693 ✭✭✭✭unkel


    noel100 wrote: »
    if you can use the 5370 units at 0.16kw
    Would equal €859

    Your sums are not realistic, don't fool yourself.

    1. 5370 is extremely optimistic of the midlands

    2. if you can use the 5370 units? Almost certainly not. How are you going to use 4kW coming into your house on a sunny day? A lot of it will be lost (go to the grid for free). If you have an EV that's always parked at home during the day, than maybe you will get close

    3. it is not EUR0.16/kWh. Most of your production is competing with night rate, which is EUR0.0665/kWh

    So your savings are probably more like 4000 units production. Half lost (this is already optimistic), other half at 6.65c, so about EUR250 per year (unless you have the EV parked at home during the day)


  • #10
    rolion
    Closed Accounts Posts: 3,362 ✭✭✭rolion


    denismc wrote: »
    I have been watching the price of domestic PV systems fall over the last number of years and I am now considering installing some in my home.


    Just an email received this morning from a PV supplier:


    427169.jpg


  • #11
    Conor20
    Registered Users Posts: 265 ✭✭Conor20


    €3k for a 5kW system is a pretty decent price! I paid about €4300 for a 2.2kW system about 9 months ago. I added four more 285 watt panels for €200 a pop to the system last month. It's generated 1935kWh so far in those 9 months. You can read the numbers I calculate for our savings here but as you'll hear from everyone, it's really about how much of the energy you use. We have two young kids in the house all day, and an electric car so we consume a lot of energy during the good solar hours. We also conume a lot of hot water the PV system generates via an iBoost hot water diversion unit. I think you could work out what you'd save by working out:
    • You're day time electricity consumption in kWh x your daytime kWh rate
    • Your Night time consumption (dishwashers, etc.) that you could move to times of "free" solar x the night kWh rate
    • You're hot water consumption x your gas kWh rate / (or if you heat water electrically, electric immersion = night kWh rate / electric shower = day kWh rate)

    That would give you a ballpark. To see what a PV system of a given size at the orientation of your roof will generate where you live, the NREL PV Estimation tool is very good.


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  • #12
    unkel
    Registered Users Posts: 64,693 ✭✭✭✭unkel


    Conor20 wrote: »
    €3k for a 5kW system is a pretty decent price!

    Not all material is included and he is installing it himself.


  • #13
    unkel
    Registered Users Posts: 64,693 ✭✭✭✭unkel


    Conor20 wrote: »
    To see what a PV system of a given size at the orientation of your roof will generate where you live, the NREL PV Estimation tool is very good.

    Cheers. A 100% south facing 4kW install in Dublin gives you a bit under 3.4MWh per year. In the midlands about 3.2MWh per year, so 5kW panels in the midlands will give no more than 4MWh (not the 5.4MWh noel100 is hoping for)


  • #14
    737max
    Closed Accounts Posts: 993 ✭✭✭737max


    Red Dwarf's Kryton on Fullycharged youtube channel had an interesting report on his powerwall and pv solution.

    he was charging his tesla and leaf off it when he could too.

    all I could think was that a certain element of society who are in to organized crime will be able to sell the panels like they used to sell lead and copper off rooves and the powerwalls are very transportable/transitable/hi-aceable.


  • #15
    unkel
    Registered Users Posts: 64,693 ✭✭✭✭unkel


    Shure there's no copper in them roof plates, boss?


  • #16
    Gumbo
    Moderators, Society & Culture Moderators Posts: 38,352 Mod ✭✭✭✭Gumbo


    My 3kw system was generating 3.3kw the other day for a period.
    I haven't got the app yet as I haven't got wifi in the house just yet so I'm just checking occasionally while looking at the site works.

    I am finglas, south facing so be interesting to see how it fairs out.
    Immersion divertor to be fitted next week all going well.


  • #17
    Effects
    Registered Users Posts: 9,761 ✭✭✭Effects


    kceire wrote: »
    My 3kw system was generating 3.3kw the other day for a period.

    What type of inverter do you have and what's it's rating?


  • #18
    Gumbo
    Moderators, Society & Culture Moderators Posts: 38,352 Mod ✭✭✭✭Gumbo


    Effects wrote: »
    What type of inverter do you have and what's it's rating?

    I'll check tomorrow.
    3.432kw today for a period.


  • #19
    rolion
    Closed Accounts Posts: 3,362 ✭✭✭rolion


    kceire wrote: »
    I'll check tomorrow.
    3.432kw today for a period.


    I highly recommend checking the system.
    There is no way that a 3Kw power PV system can generate 3.432KWh at "a period" of time ! I'll be worry about cabling,inverter and fuses.
    I hope you dont confuse generated power "up to now" with instant power "right now" :)


  • #20
    Gumbo
    Moderators, Society & Culture Moderators Posts: 38,352 Mod ✭✭✭✭Gumbo


    rolion wrote: »
    I highly recommend checking the system.
    There is no way that a 3Kw power PV system can generate 3.432KWh at "a period" of time ! I'll be worry about cabling,inverter and fuses.
    I hope you dont confuse generated power "up to now" with instant power "right now" :)

    I'll check today.
    I'm just going by what is displaying on the invertor screen.
    It could jump from 3.4 to 2.5 to 3.1 in a matter of seconds (obviously as light hits the panels).

    I haven't moved in yet so have not got the system connected to the wifi to monitor just yet.

    I do know the immersion Diverter is a My Energi Eddi unit.
    http://myenergi.uk/product/eddi/

    Ill get the invertor details soon as im there about mid day.


  • #21
    Gumbo
    Moderators, Society & Culture Moderators Posts: 38,352 Mod ✭✭✭✭Gumbo


    My invertor is a Trannenergy SGN3400TL unit.


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  • #22
    Effects
    Registered Users Posts: 9,761 ✭✭✭Effects


    kceire wrote: »
    I'll check tomorrow.
    3.432kw today for a period.

    I didn't know that a 3Kw system could produce more than that but thought maybe there was something that I wasn't aware of.

    I had read that inverters can handle 130% of their rating, or something similar.


  • #23
    freddyuk
    Registered Users Posts: 1,110 ✭✭✭freddyuk


    Has the Trannnergy SGN3400TL unit got a certificate for connection to the Irish network? If not you can be disconnected by ESB as you must have correct settings for Ireland and you must have disclosed this on your NC4 form? Please confirm as we need a database of approved inverters. I very much doubt this Chinese inverter is legally installed under the daft special Irish regulation.
    If the inverter has more watts connected than the wattage rating then it will just de rate to it's maximum output.

    If the voltage from the PV exceeds the maximum rating (580v) then the inverter will blow. I presume you have 2 parallel strings.


  • #24
    Gumbo
    Moderators, Society & Culture Moderators Posts: 38,352 Mod ✭✭✭✭Gumbo


    freddyuk wrote: »
    Has the Trannnergy SGN3400TL unit got a certificate for connection to the Irish network? If not you can be disconnected by ESB as you must have correct settings for Ireland and you must have disclosed this on your NC4 form? Please confirm as we need a database of approved inverters. I very much doubt this Chinese inverter is legally installed under the daft special Irish regulation.
    If the inverter has more watts connected than the wattage rating then it will just de rate to it's maximum output.

    If the voltage from the PV exceeds the maximum rating (580v) then the inverter will blow. I presume you have 2 parallel strings.

    Fully supplied and installed by a large solar panel company. Commissioned by them, certified by them and registered with ESB through my MPRN.


  • #25
    [Deleted User]
    Posts: 5,238 ✭✭✭[Deleted User]


    Effects wrote: »
    I didn't know that a 3Kw system could produce more than that but thought maybe there was something that I wasn't aware of.

    Standard Test Conditions: 1000W/m² @ 25°C
    Output is ~20% of input.

    I often get panels producing above rated once I've removed the inverter and associated losses from the equation.
    It's advised with a lot of controllers and inverters to only load them to 80% rated capacity because they will spike with cloud lensing and cold temp uprating (usually happens at the same time).

    It's entirely possible for 3kW peak Pv to produce 3.3kW
    One of my systems regularly produces 10% over rating (at the panel, not the inverter)


  • #26
    freddyuk
    Registered Users Posts: 1,110 ✭✭✭freddyuk


    kceire wrote: »
    Fully supplied and installed by a large solar panel company. Commissioned by them, certified by them and registered with ESB through my MPRN.

    Can you ask them for a copy of the certificate with Irish settings? It is not on the manufacturers website


  • #27
    Gumbo
    Moderators, Society & Culture Moderators Posts: 38,352 Mod ✭✭✭✭Gumbo


    freddyuk wrote: »
    Can you ask them for a copy of the certificate with Irish settings? It is not on the manufacturers website

    I can indeed. They are back in 2 weeks to fit immersion divertor and set up the wifi monitoring. Just waiting on my plumber to fit my new cylinder and heating system.


  • #28
    Effects
    Registered Users Posts: 9,761 ✭✭✭Effects


    Sir Liamalot wrote: »
    It's advised with a lot of controllers and inverters to only load them to 80% rated capacity because they will spike with cloud lensing and cold temp uprating (usually happens at the same time).

    I've got a 1.74 kW panel system but a 1.5 kW inverter supplied by the PV company.
    So I should really be looking at 2.1kW inverter or thereabouts?


  • #29
    air
    Registered Users Posts: 2,822 ✭✭✭air


    The underrating only really applies to voltage limits, not to power limits.
    It is normal practice to overrate the PV install to the inverter - eg 5kW of panels into a 4kW inverter.
    In practice very little output is lost to inverter clipping in such a scenario as the number of hours of 4kW+ output throughout the year will be negligible.
    So your company didn't do anything wrong Effects.


  • #30
    Effects
    Registered Users Posts: 9,761 ✭✭✭Effects


    Ah ok. I was worried that the inverter wouldn't handle that much power or would only output at the lower 1.5kw.


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  • #31
    air
    Registered Users Posts: 2,822 ✭✭✭air


    Effects wrote: »
    Ah ok. I was worried that the inverter wouldn't handle that much power
    It will handle it fine.
    Effects wrote: »
    or would only output at the lower 1.5kw.
    It will be capped at the lower 1.5kW figure, but in practice this isn't a big deal. For example if you had a 2kW inverter instead, the number of hours a year your inverter would output 1.75kW would be few and far between - and it's only an extra 250W in any case!


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