gramos Posted January 12, 2022 Share Posted January 12, 2022 21 hours ago, epsilonGreedy said: You normally leave at least one panel unplugged so the string is not completed until you have done ALL the DC wiring. Go and unplug one panel off each string before you do any more. Yes this is exactly what I did with each string when connecting , thanks . Link to comment Share on other sites More sharing options...
gramos Posted January 12, 2022 Share Posted January 12, 2022 Thanks , for the feedback guys . I made all the hook ups with one panel disconnected. the system is 11.2kw from Rosensolar , it comprises : 28x 400watt pv panels 2x DC combiner boxes with breakers , switches 2x Growatt SPF 5000 TL HVM WPV P 5 kw inverters 1x battery combiner box 3x life po4 48v /200 ah batteries. I hope you find this interesting ? I am treading carefully here and really happy to hear your comments , thank you . The first question is can a solar rated 10 mm2 cable be used from the combiner boxes to the inverters over a 36 metre run ? Graham Link to comment Share on other sites More sharing options...
SteamyTea Posted January 12, 2022 Share Posted January 12, 2022 25 minutes ago, gramos said: 28x 400watt pv panels Do you have a data sheet for these modules. There is usually basic specifications printed on the back of them. Link to comment Share on other sites More sharing options...
gramos Posted January 12, 2022 Share Posted January 12, 2022 Pictures of a panel specs: Link to comment Share on other sites More sharing options...
SteamyTea Posted January 12, 2022 Share Posted January 12, 2022 The open circuit voltage is a gnats under 50 V. So 14 modules in series will give you 700 V. What inverter/s do you intend to use? Link to comment Share on other sites More sharing options...
gramos Posted January 12, 2022 Share Posted January 12, 2022 Inverter specs above Link to comment Share on other sites More sharing options...
SteamyTea Posted January 12, 2022 Share Posted January 12, 2022 Says on the spec sheet that the maximum solar I put is 4.5 kW. 14 of your modules will be 5.6 kW. I may have misunderstood the spec, hard to read on my phone. Link to comment Share on other sites More sharing options...
joth Posted January 12, 2022 Share Posted January 12, 2022 43 minutes ago, gramos said: Thanks , for the feedback guys . I made all the hook ups with one panel disconnected. the system is 11.2kw from Rosensolar , it comprises : 28x 400watt pv panels 2x DC combiner boxes with breakers , switches 2x Growatt SPF 5000 TL HVM WPV P 5 kw inverters 1x battery combiner box 3x life po4 48v /200 ah batteries. I hope you find this interesting ? I am treading carefully here and really happy to hear your comments , thank you . The first question is can a solar rated 10 mm2 cable be used from the combiner boxes to the inverters over a 36 metre run ? Graham Interesting setup! I was going to ask how this would be grid tied as the SPF 5000 doesn't have a G.99 certificate AFAICT, but I see now you're making a fully offgrid system, pretty cool. 9800kWh sounds on the low side for an off-grid battery, and that much generation. Guess it depends on the usage patterns of the building, but nice thing with that system is you can always add more batteries later if needed? Link to comment Share on other sites More sharing options...
SteamyTea Posted January 12, 2022 Share Posted January 12, 2022 https://www.solar-wind.co.uk/info/dc-cable-wire-sizing-tool-low-voltage-drop-calculator There you go. A DC cable calculator. Just plug in the details and find that standard 4mm cable will be fine. Link to comment Share on other sites More sharing options...
gramos Posted January 12, 2022 Share Posted January 12, 2022 Yes I wanted a big system with 3+ days autonomy, as there is no grid going in anywhere near us and its for a house and workshop ! Usage per day is well under 3 kw Link to comment Share on other sites More sharing options...
SteamyTea Posted January 12, 2022 Share Posted January 12, 2022 9 minutes ago, gramos said: Usage per day is well under 3 kw Don't you mean 3 kWh a day? 3 kW of constant power would be 72 kWh a day. Link to comment Share on other sites More sharing options...
gramos Posted January 12, 2022 Share Posted January 12, 2022 1 minute ago, SteamyTea said: https://www.solar-wind.co.uk/info/dc-cable-wire-sizing-tool-low-voltage-drop-calculator There you go. A DC cable calculator. Just plug in the details and find that standard 4mm cable will be fine. Thanks , thats what the system specced originally ! my main concern was the length now at 36 M. Good to have some more confirmation though Link to comment Share on other sites More sharing options...
joth Posted January 12, 2022 Share Posted January 12, 2022 52 minutes ago, gramos said: Yes I wanted a big system with 3+ days autonomy, as there is no grid going in anywhere near us and its for a house and workshop ! Usage per day is well under 3 kw REmember that a 9kWh battery will give absolute best case scenario 3days of running. You need a MUCH bigger battery than that if you want guaranteed availability. At least, where I am in the UK it can be cloudy for a week or two at a time. And even then, a single day of sunshine in December might barely meet the 3kWh demand for that day, let along recharge 10days worth of depleted battery. 3kWh is impressively low! Presumably no heating or hot water in that? We average 15-20kWh per day, for everything - heating, hotwater, cooking, 2 people working at home, a bunch of computers, but no workshop! (I see the UK average is 9kWh electricity, and 33kWh of gas, per day, for a 2.4 person household) Link to comment Share on other sites More sharing options...
gramos Posted January 12, 2022 Share Posted January 12, 2022 2 hours ago, SteamyTea said: https://www.solar-wind.co.uk/info/dc-cable-wire-sizing-tool-low-voltage-drop-calculator There you go. A DC cable calculator. Just plug in the details and find that standard 4mm cable will be fine. Thanks , thats what the system specced originally ! my main concern was the length now at 36 M. Good to have some more confirmation though Link to comment Share on other sites More sharing options...
SteamyTea Posted January 12, 2022 Share Posted January 12, 2022 1 minute ago, gramos said: Thanks , thats what the system specced originally ! my main concern was the length now at 36 M. Good to have some more confirmation though Pretty sure that 4 mm is what comes out the back of the modules. Link to comment Share on other sites More sharing options...
gramos Posted January 12, 2022 Share Posted January 12, 2022 I am in Kefalonia , Greece , 38°07'24.9" N 20°34'55.0"E - This is our solar input , my calculations were based on . A surplus of power all summer and sufficient reserve during the winter months . Quite right , Steamy Tea , kWh per day , based on current use . Average Solar Insolation figures Measured in kWh/m2/day onto a solar panel set at a 37° angle: (Optimal winter settings) Jan Feb Mar Apr May Jun 3.77 4.16 5.15 5.57 5.46 5.83 Jul Aug Sep Oct Nov Dec 6.01 6.20 6.01 5.19 3.72 3.20 Link to comment Share on other sites More sharing options...
gramos Posted January 12, 2022 Share Posted January 12, 2022 1 hour ago, joth said: REmember that a 9kWh battery will give absolute best case scenario 3days of running. You need a MUCH bigger battery than that if you want guaranteed availability. At least, where I am in the UK it can be cloudy for a week or two at a time. And even then, a single day of sunshine in December might barely meet the 3kWh demand for that day, let along recharge 10days worth of depleted battery. 3kWh is impressively low! Presumably no heating or hot water in that? We average 15-20kWh per day, for everything - heating, hotwater, cooking, 2 people working at home, a bunch of computers, but no workshop! (I see the UK average is 9kWh electricity, and 33kWh of gas, per day, for a 2.4 person household) water heating by solar, lpg gas oven , woodburning stove for heat , passiv haus levels of insulation , triple glazing and of course when required a genny ! 1 hour ago, joth said: Link to comment Share on other sites More sharing options...
joth Posted January 12, 2022 Share Posted January 12, 2022 31 minutes ago, gramos said: I am in Kefalonia , Greece , HA! ok fine ? Yeah for offgrid the monthly kWh estimate only tells part of the story, an estimate of how many contiguous days are likely to have no or next to no sun is also key information, but I'm going to wildly guess Mediterranean climate helps a lot here. (That said, we spent 2 weeks in Majorca November just gone, and it did not stop raining once...) Link to comment Share on other sites More sharing options...
gramos Posted January 12, 2022 Share Posted January 12, 2022 1 hour ago, joth said: HA! ok fine ? Yeah for off grid the monthly kWh estimate only tells part of the story, an estimate of how many contiguous days are likely to have no or next to no sun is also key information, but I'm going to wildly guess Mediterranean climate helps a lot here. (That said, we spent 2 weeks in Majorca November just gone, and it did not stop raining once...) Yes the insolation is high here , I am looking at the batteries being fully charged by 1000 and running all appliances during the day from solar . so a lot of panels was high on the specification and a change of power usage will happen too. Its a new build and everything is geared to minimise electric consumption . Like all new projects , of course , there will doubtless be modifications to be implemented ! These islands have about half the rainfall of England but /? the sunlight . 1 hour ago, joth said: 4 hours ago, SteamyTea said: https://www.solar-wind.co.uk/info/dc-cable-wire-sizing-tool-low-voltage-drop-calculator There you go. A DC cable calculator. Just plug in the details and find that standard 4mm cable will be fine. Thanks , thats what the system specced originally ! my main concern was the length now at 36 M. Good to have some more confirmation though Link to comment Share on other sites More sharing options...
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