Catford Bags Posted February 8 Share Posted February 8 (edited) Now that you lot have very kindly helped me with my cabling issues on a different thread, my mind has turned to high level design. My main priority is return on investment. (i'd like to live to see the benefit - i'll be 54 tomorrow, good teeth but addicted to biscuits) I’m not a spark but want to install as much of the system myself. Ideally it would be a flexible system where I have the ability to add more (should I win the lottery). The budget is tight. I do have a mate who is an MCS installer but he's not a good mate - IE. I could possibly get him to do final commision and sign it off but I can't take too many liberties. Question - i was looking at 5kw of panels (on a diy groundmount (using MCS bars)) and a 5kw hybrid inverter and a 5kw battery. I'm now wondering whether 3.6kw inverter actually makes better sense. Any thoughts welcome. Edited February 8 by Catford Bags Link to comment Share on other sites More sharing options...
SteamyTea Posted February 8 Share Posted February 8 31 minutes ago, Catford Bags said: on a diy groundmount If it is over 9m2 then you need planning permission. 32 minutes ago, Catford Bags said: i was looking at 5kw of panels (on a diy groundmount (using MCS bars)) and a 5kw hybrid inverter and a 5kw battery The modules and inverter are rated as kW, battery as kWh. But it really depends as some some inverters have minimum lower power setting i.e. 200W, so they often will not run lights off the battery. There are 2 main types of systems that incorporate batteries. One that puts the batterers on the DC side and the other on the AC side. I think most people go for hybrid inverters that that allow batteries to be charged from the AC side. 36 minutes ago, Catford Bags said: a mate who is an MCS installer but he's not a good mate - IE. I could possibly get him to do final commision and sign it off but I can't take too many liberties. There is a lot more to an MCS installation than just final signoff. Generally why MCS companies will not sign off systems they have not installed. Link to comment Share on other sites More sharing options...
Wil Posted February 8 Share Posted February 8 I have 5kWp of panels connected to a 3.68kWp inverter. All self installed. Means a bit of clipping at max output but it starts generating slighting earlier and hasn’t been any issues so far. Hopefully the panel degredation will never be an issue as it was oversized to begin with. Lack of MCS currently means no payment for export, but that may be able to be changed. Try and size to self-consume. Hybrid batteries inverters charge the batteries direct from DC and allow for G98 install. AC batteries mean g99 regs as both the solar inverter and the battery inverter need to be summed as they could both be outputting at the same time. Link to comment Share on other sites More sharing options...
Alan Ambrose Posted February 8 Share Posted February 8 The default set-up these days seems to be 'grid-tied' which means you can't use your battery when the grid is down. That may or may not be a concern for you? The 'non-grid-tied' / 'off grid' / 'island mode' is more complicated but could be more useful if grid power outages are a factor. Link to comment Share on other sites More sharing options...
Dillsue Posted February 8 Share Posted February 8 Whether a 3.68kw inverter makes better sense than a 5kw one only you can decide. Sticking to 3.68kw means you could install under G98 and avoid the G99 application fee for a 5kw inverter- £300 fee for us in 2022. Down side is the peak generation from 5kw of panels could be lost for a small amount of time but if you are charging DC coupled batteries then you won't loose so much as you could be charging your batteries. How have you decided on 5kwh of batteries? As mentioned above and on the other thread, you need planning for an array over 9m2. If your array is hidden from view that might not concern you. If you want a flexible system then you can't beat micro inverters/optimisers for facilitating add ons and also allowing different wattage panels to be used in the same string. They'll also improve generation if you've got partial array shading Link to comment Share on other sites More sharing options...
SteamyTea Posted February 8 Share Posted February 8 1 minute ago, Dillsue said: 5kwh !!! Link to comment Share on other sites More sharing options...
Dillsue Posted February 8 Share Posted February 8 3 minutes ago, SteamyTea said: !!! Be thankful you got the right letters and in the correct order. It was the thought of another bollocking that reminded me to add the "h" but doing 1 fingered caps on a tablet is a few keystrokes too much 1 Link to comment Share on other sites More sharing options...
SteamyTea Posted February 8 Share Posted February 8 12 minutes ago, Dillsue said: doing 1 fingered caps on a tablet is a few keystrokes too much Pop kW, kWh, MJ and J.s-1 into the autocorrect. Link to comment Share on other sites More sharing options...
Catford Bags Posted February 8 Author Share Posted February 8 1 hour ago, Dillsue said: Whether a 3.68kw inverter makes better sense than a 5kw one only you can decide. Sticking to 3.68kw means you could install under G98 and avoid the G99 application fee for a 5kw inverter- £300 fee for us in 2022. Down side is the peak generation from 5kw of panels could be lost for a small amount of time but if you are charging DC coupled batteries then you won't loose so much as you could be charging your batteries. How have you decided on 5kwh of batteries? As mentioned above and on the other thread, you need planning for an array over 9m2. If your array is hidden from view that might not concern you. If you want a flexible system then you can't beat micro inverters/optimisers for facilitating add ons and also allowing different wattage panels to be used in the same string. They'll also improve generation if you've got partial array shading Thanks All - 3.68kw inverter and G98 definately seems to be making sense. Happy to store any peak excess in the battery. My consumption is currently averaging 15kwh/day. I'm assuming peak mid day production is misaligned with peak teatime consumption so it would be normal to store peak production in a battery anyway.. I've decided on 5kwh of battery because i think that it is the max that I can currently afford. Do you think I should be going larger ? Ideally i'd add another battery at a later point if i can afford it. Also my aim is ulitise everything I produce rather than sending stuff back to the grid. I'm aware of planning constraints for groundmounts. I'm not bothered about covering essential loads during a power cut. Dillsue - would you be able to expand on your micro inverter/optimiser suggestion please (and assume that you are talking to an unenlightened person). Link to comment Share on other sites More sharing options...
Dillsue Posted February 9 Share Posted February 9 12 hours ago, Catford Bags said: I've decided on 5kwh of battery because i think that it is the max that I can currently afford. Do you think I should be going larger ? Ideally i'd add another battery at a later point if i can afford it. Also my aim is ulitise everything I produce rather than sending stuff back to the grid. You mentioned previously that your main priority is ROI so you need to work your own figures and do a load of research. Plenty of discussion on battery ROI and to me at least its not clear cut that batteries make financial sense. If you go down the battery route and are constrained now, then design your system for how you'd like it to be and ensure your design allows for expansion when funds allow. 12 hours ago, Catford Bags said: Dillsue - would you be able to expand on your micro inverter/optimiser suggestion please (and assume that you are talking to an unenlightened person). Have a look at Enphase for micro inverters and Tigo/SolarEdge for optimisers as they all explain the advantages over conventional string setups. Disadvantages are additional cost and access for replacement if they fail but that's only applicable to roof mounted systems and likely won't apply to your ground mounted system. You can avoid some of the extra cost by buying surplus kit online- Solaredge optimisers can be had for £20 new rather the usual £50-70 but don't rush into buying until you understand what you are buying. 1 Link to comment Share on other sites More sharing options...
Catford Bags Posted March 1 Author Share Posted March 1 Could anyone tell me whether there is a cost for G99 applications ? - can see the form on the Scottish Power website but nothing about charges..... Link to comment Share on other sites More sharing options...
Dillsue Posted March 1 Share Posted March 1 SPEN charged me £300 for a G99 a couple of years ago. Couldn't fault SPENs design guys Link to comment Share on other sites More sharing options...
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