Solar PV Advice Please

edited 30 November -1 at 1:00AM in Green & Ethical MoneySaving
21 replies 4K views
2

Replies

  • Martyn1981Martyn1981 Forumite
    12K Posts
    Part of the Furniture 10,000 Posts Name Dropper Photogenic
    ✭✭✭✭✭
    The different aspects are remote from each other so they will be on seperate inverters. The garage is around 30m externally detached from house on a shared courtyard.

    Thanks

    Slight hitch then, if you have separate inverters, each will need to be sized to meet the relevant array, so I expect the sum of two inverters to be higher than a single inverter which can take into account that both systems won't peak together.

    The DNO will want to add the two inverters together to get the theoretical export, so I really think now that you will need to get prior permission from them.

    No biggie I suppose as that looked like the route you would have to take anyway, but more likely now.
    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.
  • Quick question -
    Looks like its pushing ahead and have the option of two inverters:
    - Solis - 5 yr warranty - wifi and gsm monitoring
    - Growatt - 10 yr warranty - wifi only

    Anybody have any experience and feedback of either?

    Thanks
    C
    6.3kW system in Loughborough. 15 JASolar 300w panels on main roof SSE (no shading) with 4.2kW Growatt Inverter. 6 JASolar 300w panels on garage roof WSW (some winter shading) with a 1.65kW Growatt Inverter. Running a Nissan Leaf 24kW and considering battery storage :)
  • Martyn1981Martyn1981 Forumite
    12K Posts
    Part of the Furniture 10,000 Posts Name Dropper Photogenic
    ✭✭✭✭✭
    Quick question -
    Looks like its pushing ahead and have the option of two inverters:
    - Solis - 5 yr warranty - wifi and gsm monitoring
    - Growatt - 10 yr warranty - wifi only

    Anybody have any experience and feedback of either?

    Thanks
    C

    Hiya, no knowledge nor experience, but I would suggest you Google them + extended warranties, and see what's on offer and for how much. [Just as a reference Solaredge extensions from 12yrs to 20yrs are about £100] So this could be a good investment for you for peace of mind.
    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.
  • pensionpawnpensionpawn Forumite
    426 Posts
    Third Anniversary 100 Posts Name Dropper
    ✭✭
    Hi Chris Wiseman. Personally I'm not convinced about solar inverters if they are offsetting gas. It's great to see your excess PV go into the HW tank, or underfloor heating, however it only saves me my gas rate (~3p/kWhr) plus a fiddle factor for an ageing gas boiler being less efficient than electric. My solar diverter cost me in the region of £400 and it needs to divert just over 13Mwhrs to RoI. Bearing in mind that the saving is not the actual amount diverted to the HW tank, but the difference between the available excess PV and the full power requirement of the destination, RoI will doubtfully ever be achieved. I've chalked it up to (lack of) experience!

    BTW, the save can be argued for car chargers, unless your priority is rapid charging.
  • pensionpawnpensionpawn Forumite
    426 Posts
    Third Anniversary 100 Posts Name Dropper
    ✭✭
    Hi Chris Wiseman. Regarding your post on split 10kW system. I have a slightly smaller system on two aspects (4kWs East & 3.12kWs West) and they feed a 6kW Solaredge inverter via power optimisers (due to chimney stack shading and two strings). Besides the distance between your runs, which may not be an issue, in theory you could run off one 10kW (probably 8kWs would do it) inverter, if such a device exists within your budget
  • gefnewgefnew Forumite
    194 Posts
    Part of the Furniture 100 Posts
    Hi Chris
    sma inverter planning software, could be of some interest. go to uk web site downloads/archive sunny design.


    regards
  • pinnkspinnks Forumite
    835 Posts
    Sixth Anniversary 500 Posts Photogenic Rampant Recycler
    ✭✭✭
    I am afraid that I disagree slightly with the ROI on diverters point.

    I have been recording gas and electricity use for a decade now and see that since I have PV/diverter and turn the boiler off over the summer, producing all hot water using PV I save about £80 of gas. i.e. I know that my monthly gas use over the 5 or 6 months the boiler is turned off used to be about £80. Now it is £0.

    This actually equates to about the same as using the kWh cost for electricity times the number of kWh I divert over that period, i.e. I can use the kWh cost of electricity to calculate the ROI on my inverter. Why is that?

    Well, it's the inefficiency of using the boiler only for hot water and of heating about 22m of unlagged and unlaggable (without ripping up floors) pipe between boiler and tank. The heat loss in those pipes means I need about 3 times the kWh of gas to heat the water than I do of electricity, making gas as expensive over the summer as running the immersion.

    I also estimate that I save about £20 in addition over the other months as I get a reasonable contribution to my hot water on a good proportion of those darker and colder days.

    So, about £80 verifiably saved gas and a guess at £20 in addition means my return on investment is about £100 per year, so about 3 1/2 to 4 years to repay the investment.

    Real data is always better than guesswork:T
    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
  • CoastalwatchCoastalwatch Forumite
    1.8K Posts
    1,000 Posts Third Anniversary Name Dropper
    ✭✭✭
    Hi Chris Wiseman. Regarding your post on split 10kW system. I have a slightly smaller system on two aspects (4kWs East & 3.12kWs West) and they feed a 6kW Solaredge inverter via power optimisers (due to chimney stack shading and two strings). Besides the distance between your runs, which may not be an issue, in theory you could run off one 10kW (probably 8kWs would do it) inverter, if such a device exists within your budget
    I too run a 6kw SolarEdge Inverter off of a larger split system, 8.85 kW, it copes very well and the software that goes with it means I am able to view the output of each individual panel at any given time.
    As Mart suggested earlier here I took out the extended warranty taking it to twenty years.

    I believe 6kW is the largest SolarEdge inverter available and would cope adequately, however if you do feel the need to go for two smaller inverters then suggest you don't over spec them. ie a 4kW and 3kW max. But you then have two inverters to purchase, install, find the space for and two extended warranty's if you take that route!

    Good luck with whatever you choose.
    East coast, lat 51.97. 8.26kw SSE, 23° pitch + 0.59kw WSW vertical. Nissan Leaf plus Zappi charger and 2 x ASHP's. Still waiting for V2H and home storage to become available at sensible cost.
  • pensionpawnpensionpawn Forumite
    426 Posts
    Third Anniversary 100 Posts Name Dropper
    ✭✭
    Hi pinnks. My divert system 'saved me' around £30 in gas (by comparing meter readings) in the first year after going solar, so saving £80 is mightily impressive. However as you've illustrated that is due to the thermal losses in your premises nose diving due to insulation issues. My boiler is 22 years old and is probably now only around 80% efficient however the pipe runs are short (2m vertically from boiler to tank) and no more than 5m - 10m to the furthest hot water outlet. Over the last couple of years I've added UFH to the second output of my solar divert so I'm now probably saving a little more over the year, making the RoI around 8 years. That said, I doubt very much that the device will last that long. With hindsight would I buy another? Definitely no. Battery is the way forward as it allows you to store energy, which divert cannot. Unfortunately battery is way too expensive at present. However an EV may be worth a punt if the subsidies don't vanish this month....
  • Martyn1981Martyn1981 Forumite
    12K Posts
    Part of the Furniture 10,000 Posts Name Dropper Photogenic
    ✭✭✭✭✭
    Hi Chris Wiseman. Personally I'm not convinced about solar inverters if they are offsetting gas. It's great to see your excess PV go into the HW tank, or underfloor heating, however ......

    Hiya, silly point, but just to be clear, Chris was asking about inverters not diverters, in case the discussion is getting confusing to readers.
    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.
This discussion has been closed.
Latest MSE News and Guides

Energy price cap could be extended beyond 2023

New plans have just been announced by the Government

MSE News

Cheap contents insurance for tenants

DON'T assume your landlord covers you

MSE Guides

Summer sizzlers round-up

Incl £2ish sun cream & £1.50 disposable BBQs

MSE Deals