DragonQ Posted January 27, 2023 Share Posted January 27, 2023 We've narrowed down to two quotes for a solar/battery system to go alongside our existing Zappi EV charger. Both quotes feature SolarEdge optimisers (because there are several trees shading our roof) and a ~10kWh battery. However, quote 1 features 5.4kW panel output and an AC coupled system (SolarEdge inverter for solar, another inverter matching the battery brand). Quote 2 has 10% lower peak panel output (4.9kW) but uses a hybrid SolarEdge inverter. Which would you go for out of the two and why? I figure the higher capacity solar is better overall, whereas having a hybrid system will be more efficient in summer due to having 2 less AC/DC conversions for solar -> battery -> house. Having 2 separate inverters will mean we can draw more from solar and the battery at the same time but this would be rare (e.g. charging car if we forgot to plan ahead). Quote 1 is a bit cheaper but quote 2 can start sooner. We will likely be adding more panels in a couple of years. Is there anything else I should consider? Thanks for any input. Link to comment Share on other sites More sharing options...
PhilT Posted January 27, 2023 Share Posted January 27, 2023 which makes and models specifically? Link to comment Share on other sites More sharing options...
Marvin Posted January 27, 2023 Share Posted January 27, 2023 Hi @DragonQ At what rate are you proposing to charge your EV? We have PV and an EV and experience charging using mainly the PV. Link to comment Share on other sites More sharing options...
DragonQ Posted January 27, 2023 Author Share Posted January 27, 2023 EV charge point is 7.4kW. Quote 1 is Eurener panels with GivEnergy battery & inverter. Quote 2 is Tiger panels with LG battery (apparently compatible with SolarEdge hybrid inverter). In summer the plan would be to charge the battery with solar on sunny days and the car too if there's any excess. Given EV charging requires a minimum of 1.4kW and we're never likely to have that spare during winter, I suspect we'd charge the car at night (cheap rate). The battery would also charge at night on less sunny days, maybe topped up during the day on sunny days. Link to comment Share on other sites More sharing options...
PhilT Posted January 27, 2023 Share Posted January 27, 2023 17 minutes ago, DragonQ said: LG battery (apparently compatible with SolarEdge hybrid inverter). I could be wrong but I think this needs the Storedge system for control and monitoring? Link to comment Share on other sites More sharing options...
DragonQ Posted January 27, 2023 Author Share Posted January 27, 2023 (edited) 51 minutes ago, PhilT said: I could be wrong but I think this needs the Storedge system for control and monitoring? Yes the hybrid inverter proposed in quote 2 is a StorEdge: https://www.solaredge.com/sites/default/files/se-storedge-single-phase-with-hd-wave-datasheet.pdf Edited January 27, 2023 by DragonQ Link to comment Share on other sites More sharing options...
PhilT Posted January 27, 2023 Share Posted January 27, 2023 3 hours ago, DragonQ said: Yes the hybrid inverter proposed in quote 2 is a StorEdge: https://www.solaredge.com/sites/default/files/se-storedge-single-phase-with-hd-wave-datasheet.pdf The main issue which springs to mind is backup. I can see what looks like an impressive automatic backup feature on the Givenergy system but can't see anything for the StorEdge system although possibly that link you quoted doesn't mention it? Link to comment Share on other sites More sharing options...
DragonQ Posted January 27, 2023 Author Share Posted January 27, 2023 1 minute ago, PhilT said: The main issue which springs to mind is backup. I can see what looks like an impressive automatic backup feature on the Givenergy system but can't see anything for the StorEdge system although possibly that link you quoted doesn't mention it? I think both systems would offer that based on this link: https://www.solaredge.com/solutions/grid-backup#/ I can double check though because we'd definitely want that. There is no phone signal here so having internet + WiFi during powercuts will be very helpful. Link to comment Share on other sites More sharing options...
Marvin Posted January 27, 2023 Share Posted January 27, 2023 5 hours ago, DragonQ said: EV charge point is 7.4kW. Quote 1 is Eurener panels with GivEnergy battery & inverter. Quote 2 is Tiger panels with LG battery (apparently compatible with SolarEdge hybrid inverter). In summer the plan would be to charge the battery with solar on sunny days and the car too if there's any excess. Given EV charging requires a minimum of 1.4kW and we're never likely to have that spare during winter, I suspect we'd charge the car at night (cheap rate). The battery would also charge at night on less sunny days, maybe topped up during the day on sunny days. On our 5.12kW PV system we have several records of producing 24kWh a day in August 2022 and about nothing on some days in December. Link to comment Share on other sites More sharing options...
Dillsue Posted January 27, 2023 Share Posted January 27, 2023 17 minutes ago, DragonQ said: I think both systems would offer that based on this link: https://www.solaredge.com/solutions/grid-backup#/ I can double check though because we'd definitely want that. There is no phone signal here so having internet + WiFi during powercuts will be very helpful. Definitely check the back up interface is available and certified for the UK. Its been available overseas for a while but if its now certified for the UK its a fairly recent event- I think last year or so. AFAIK, Energybank is Solaredges current battery offering for new systems and connects directly to the current HD wave inverters. I think the LG batteries are now intended to be used with a storedge interface for adding batteries to older inverters. I think you can still hook up LG batteries to the current inverters but it doesnt seem to be the norm. Maybe theres a cost saving with LG batteries and Storedge interface vs energybank??? Link to comment Share on other sites More sharing options...
PhilT Posted January 27, 2023 Share Posted January 27, 2023 1 hour ago, DragonQ said: I think both systems would offer that based on this link: https://www.solaredge.com/solutions/grid-backup#/ It does indeed, that's good. I have a system like your quote 1, using the much less expensive non-hybrid SolarEgdge inverter for the panels/optimisers and a dedicated battery+inverter. It works really well for me. Is the multiple AC/DC conversion really a problem? I'm not sure. So I guess your choice mainly depends on the relative cost for the perfromance on offer, and any space limitations depending on battery pack dimensions and the possibility of having 2 inverters instead of 1. Link to comment Share on other sites More sharing options...
DragonQ Posted January 30, 2023 Author Share Posted January 30, 2023 On 27/01/2023 at 18:04, PhilT said: It does indeed, that's good. I have a system like your quote 1, using the much less expensive non-hybrid SolarEgdge inverter for the panels/optimisers and a dedicated battery+inverter. It works really well for me. Is the multiple AC/DC conversion really a problem? I'm not sure. So I guess your choice mainly depends on the relative cost for the perfromance on offer, and any space limitations depending on battery pack dimensions and the possibility of having 2 inverters instead of 1. I think given the relative costs of the system, losing a few percentage points of efficiency by having 2 inverters won't make a difference in the lifespan of the system. We're going to go with quote 1, assuming they pass all our other criteria (availability, fast track G99 understanding, etc.). Thanks for the advice everyone. Link to comment Share on other sites More sharing options...
joth Posted January 30, 2023 Share Posted January 30, 2023 On 27/01/2023 at 16:28, DragonQ said: I think both systems would offer that based on this link: https://www.solaredge.com/solutions/grid-backup#/ I can double check though because we'd definitely want that. There is no phone signal here so having internet + WiFi during powercuts will be very helpful. As others mentioned, which SolarEdge gear supports grid failover it doesn't have the necessary approvals for use in the UK. (You also need an inverter with the dual AC outputs, battery backed and direct grid, which their new HD Wave inverters don't have so needs a transfer switch of some sort). Also to check the other snag here - who is your internet supplier over what technology? Anything using FTTC (openreach VDSL or virgin media) will generally go dark during a power cut anyway, as the local cabinet is most likely on the same supply. It's not like the old days of direct copper to the exchange with its own UPS. Hopefully FTTP would start to reverse that. Link to comment Share on other sites More sharing options...
DragonQ Posted January 30, 2023 Author Share Posted January 30, 2023 1 hour ago, joth said: As others mentioned, which SolarEdge gear supports grid failover it doesn't have the necessary approvals for use in the UK. (You also need an inverter with the dual AC outputs, battery backed and direct grid, which their new HD Wave inverters don't have so needs a transfer switch of some sort). Also to check the other snag here - who is your internet supplier over what technology? Anything using FTTC (openreach VDSL or virgin media) will generally go dark during a power cut anyway, as the local cabinet is most likely on the same supply. It's not like the old days of direct copper to the exchange with its own UPS. Hopefully FTTP would start to reverse that. Currently FTTC but FTTP is being installed in our road as we speak. I have no idea if FTTP will continue to work during a power-cut, I doubt we will know until one happens. Given the lack of mobile signal we may have to fork out for a standard copper landline as well just in case. Link to comment Share on other sites More sharing options...
billt Posted January 30, 2023 Share Posted January 30, 2023 The fibre interface box needs local power, so you'll still lose internet if local power goes. Link to comment Share on other sites More sharing options...
joth Posted January 30, 2023 Share Posted January 30, 2023 1 hour ago, billt said: The fibre interface box needs local power, so you'll still lose internet if local power goes. yeahbut that's supplied from the house's own main feed, so in the context of this discussion this would obviously need to be on the house battery with failover (or a UPS), same as the IP router and Wifi APs. It's all the other gubbins between house and exchange that's in question, but I think with FTTP there should be much less of that gubbins. (That's kinda the whole point of fibre) - In fact, you can ask OpenReach for a a modem battery backup to keep the household phoneline working without the need to retain copper pair to premises https://www.bt.com/help/landline/fibre-home-phone-service--questions-about-the-battery-back-up-un Link to comment Share on other sites More sharing options...
DragonQ Posted February 6, 2023 Author Share Posted February 6, 2023 Bit of an update, turns out it's more complicated to get parts that both do what we want and work together without costing a ridiculous amount. I didn't realise SolarEdge single phase inverters only work with high voltage batteries, which are more expensive and also there's fewer of them to choose from. I was offered a Solis inverter for the battery instead, allowing a wider range of low voltage batteries, but Solis don't allow for data/config locally (at least not easily), whereas SolarEdge and GivEnergy do. GivEnergy has the disadvantage of only allowing 3.6 kW to be drawn from the battery, meaning every time we turn the kettle on we'll have to draw from the grid. Probably not much cost-wise but just feels silly. Also, we may have to choose between a 10 or 16 kWh battery, which is mildly annoying as we use ~12 kWh during peak times (range over the last month is 9.5 to 13.5 kWh). So if we get the 10 kWh we'll have to draw from the grid at peak times maybe every other day during winter. If we get the 16 kWh we'd never need to import at peak rates and we can store a bit more during the summer if the car is fully charged, but it'll never pay for itself unless we can exploit Octopus Agile import/export rates. I have no idea whether this is worth it compared to just sticking with a low flat rate at night (for the car and battery during winter). It's difficult to choose the "right" system but given it's so expensive I want to get it right! 🤔 Link to comment Share on other sites More sharing options...
Simon R Posted February 6, 2023 Share Posted February 6, 2023 Hi, I'm running a GivEnergy system 3.6kW inverter + PV with their 9.5kWh battery storage with Octopus intelligent tariff. Our house is heated/cooled with small 3.5kW Midea a2a unit. Our practical experience is that we use very little peak rate electricity. In winter we run the a2a unit to heat overnight 23:00 to 05:30 and then as we need it depending on solar gain, it's unusual to draw from the grid during the day. In summer we use the a2a to keep the house down to 22c and it's always running on solar, so again no peak rate. I also have an EV which I'm setting up to charge automatically when the battery store reaches 90% (and PVs are inputting) and stop when the battery is depleted to 40%. By doing this I should be able to reduce my export to a minimum. Link to comment Share on other sites More sharing options...
PhilT Posted February 6, 2023 Share Posted February 6, 2023 2 hours ago, DragonQ said: every time we turn the kettle on we'll have to draw from the grid wow that's some kettle! None of our appliances apart from the heat pump (at start up) draw more than 2kW. I went round the spreadsheet houses for weeks trying to resolve this conundrum. The only solution I could justify on financial grounds was a non hybrid 3kW HD wave to work the optimisers on the panels because of our double gable roof, and a separate 3kW battery+inverter. I get full control of all that using an app, and using Octopus Cosy tariff the small battery fits in really well but it's getting worked extremely hard - on sunny days like today it's fully charging and discharging three times a day. Link to comment Share on other sites More sharing options...
DragonQ Posted February 6, 2023 Author Share Posted February 6, 2023 (edited) 1 hour ago, Simon R said: Hi, I'm running a GivEnergy system 3.6kW inverter + PV with their 9.5kWh battery storage with Octopus intelligent tariff. Our house is heated/cooled with small 3.5kW Midea a2a unit. Our practical experience is that we use very little peak rate electricity. In winter we run the a2a unit to heat overnight 23:00 to 05:30 and then as we need it depending on solar gain, it's unusual to draw from the grid during the day. In summer we use the a2a to keep the house down to 22c and it's always running on solar, so again no peak rate. I also have an EV which I'm setting up to charge automatically when the battery store reaches 90% (and PVs are inputting) and stop when the battery is depleted to 40%. By doing this I should be able to reduce my export to a minimum. Thanks for that, sounds similar to what we'd be doing. Is that the Gen2 3.6kW hybrid inverter? The issue with GivEnergy is that they only sell 1 standalone inverter (non-hybrid), which is only 3 kW. Given SolarEdge optimisers require their inverters, this limits the possibilities somewhat. What's your average daily consumption? Over the last 3 months our average daily usage is 23.5 kWh, with around 50% of that being at peak times. Background usage is ~350 W. So the breakdown is: - Peak usage: ~11.75 kWh - Car off-peak usage: ~7 kWh (hard to tell exactly as we don't have a smart charge point yet) - Background off-peak usage: ~2.1 kWh - General off-peak usage: ~2.65 kWh (dishwasher, washing machine, timed charging of hoover/mower/toys/etc.) Obviously these are averages. Any day we use the oven sees higher peak rate usage, weekends see lower off-peak usage for car charging. 1 minute ago, PhilT said: wow that's some kettle! None of our appliances apart from the heat pump (at start up) draw more than 2kW. I went round the spreadsheet houses for weeks trying to resolve this conundrum. The only solution I could justify on financial grounds was a non hybrid 3kW HD wave to work the optimisers on the panels because of our double gable roof, and a separate 3kW battery+inverter. I get full control of all that using an app, and using Octopus Cosy tariff the small battery fits in really well but it's getting worked extremely hard - on sunny days like today it's fully charging and discharging three times a day. Heh, I saw our usage jump from ~500 W to a steady 3 kW with the ketlle on, so I'm guessing it's around 230V/10A. By itself not a problem but if we have anything else on (oven, washing machine, tumble dryer, air con) that means drawing from the grid if we have a GivEnergy battery. What brand inverter+battery do you have? Edited February 6, 2023 by DragonQ Link to comment Share on other sites More sharing options...
PhilT Posted February 6, 2023 Share Posted February 6, 2023 10 minutes ago, DragonQ said: What brand inverter+battery do you have? https://lr-renewables.co.uk/product/lux-acs-3600-3-2-greenlinx-storage-bundle-fully-installed/ Link to comment Share on other sites More sharing options...
Simon R Posted February 6, 2023 Share Posted February 6, 2023 23 minutes ago, DragonQ said: Is that the Gen2 3.6kW hybrid inverter? It's a gen 1 hybrid and our daily average is in the 12kWh region, which includes our EV charging. Our MVHR and other odds and ends result in around 400w background usage. With a 4kW PV array we are exporting even at this time of year, so if the suns shining the washing machine and dish washer get used during the day. Our battery was full by 10am today, so a lot of your peak usage 11.5kWh will come directly from PV. Dark blue is battery charging, green is load, yellow solar and red grid. Link to comment Share on other sites More sharing options...
Simon R Posted February 6, 2023 Share Posted February 6, 2023 I should have mentioned that Octopus are offering a home package with inverter +PV + battery. I don't know the price, but from my dealings with them I expect it will be good. Link to comment Share on other sites More sharing options...
Simon R Posted February 6, 2023 Share Posted February 6, 2023 56 minutes ago, Simon R said: our daily average is in the 12kWh region That's out grid consumption, actual is 19-21kWh, the balance coming from solar. Link to comment Share on other sites More sharing options...
SteamyTea Posted February 6, 2023 Share Posted February 6, 2023 1 hour ago, Simon R said: It's a gen 1 hybrid and our daily average is in the 12kWh region, which includes our EV charging Do you know the sampling rate? From the charts it looks reasonably fine. Link to comment Share on other sites More sharing options...
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