macafrican

Thanks, Sunsynk and Deye are what shows up best rated, if one can go by ratings 😕 I reckon one 3p that can jump and side step in software is better than three single phase trying to connect to one solar array and also at same time run three unbalanced loads with ability to export. KISS

Thanks Meerkat, to date I only have experience of old days (2015) grid tied residential on LV feeder no storage and very large (over 1MW own transformer) with big storage. This middle ground seems to be a minefield. if this was your own house, would you go one 3p hybrid onto one large battery or do three single phase? I do relay cancel my one 3p load already if eskom is off.

did some more reading and all I can find under export unity is one may export active power only, voltage at allowable higher V than grid side for the current to go that direction and obv same frequency. So I might have it wrong that the old SMA grid-tied inverter would at times export 0+0+0 if zero is what’s available on any one of the three phases. That is how the installers described to me and one of their bosses helped write the first NRS097 way back when. at moment what is the “best” three phase inverter?

Getting loads per phase balanced by juggling which breaker is on which phase would be very tough mainly because the reason for unbalance varies so much. Is the oven on, is the pool pump running, which rooms’ aircons are on, is the backup system recharging after loadshed, etc. I am fairly certain my council does outright not allow having an inverter per phase.

I am going to look at adding solar so thought may as well move all the solar onto the new 3p hybrid inverter. There are CT on the council 3p incomer and the SMA has its internal current meters. Part of my thinking is I keep my loads split as they are, and keep the smaller existing lifepo4 as backup on the protected phase since it is there already. So essentially just add solar, add storage available for all three phases and for optimising how much solar I self-consume by allowing thee 3p storage to draw down before taking council when there is no loadshedding. If my timing is bad and solar is bad and there is loadshedding, I would still be able to continue on the protected phase. Because of my sometimes unbalanced loads, was just wondering about how hybrids handle this. If there is no grid they can handle unbalanced phase loads, so was hoping they can also then juggle that if solar is 4+4+4 and battery is full and loads are 4+1+1, it exports 2+2+2 rather than how 3p SMA grid tied does 0+0+0.

I’d have to go look probably in NRS097 under shared LV connection. Pretty sure the council SSEG rules also requires unity.

I doubt that is legal in terms of NRS rules. NRS097 specifies unity export?

Eugene : I have a three phase borehole and presently one of my home phases is backed up with battery. What sparky did was add a relay so that if grid is off, the borehole cannot try and run with only one phase powered off the battery.

My home solar system is old, is just solar to three phase SMA grid-tied inverter and then on one phase in my DB I have a battery inverter that carries those loads during loadshed. I do export and I do get credit for it, but a weakness (besides being off in loadshed) is that the way the SMA works in my understanding is that it will only export at the lowest nett kW of the three phases. So if solar is 4+4+4 and loads are 3+1+1 across phases, then it will export 1+1+1. reason for unbalanced is mainly because when we put the loadshed on one phase, we split things like aircons, stove, pool pump across the unprotected phases and all the lights and plugs are on the protected phase. So at times we could have aircons and pool pump running hard, while the protected phase is idling along. And also after loadshed that loadshed inverter draws a lot recharging battery on protected phase in addition to the loads on that phase running. I got my hands on two 15kWh batteries and am considering (1) increasing solar and (2) replacing the SMA with a hybrid of 20-25 kW. (I am on a 30A council three phase connection). So question is with hybrid inverter, would it sort the solar + battery source better? I imagine that at minimum if loads are unbalanced and battery is not yet full, it will satisfy the 3+1+1 loads and take the 1+3+3 first to battery. Then when battery full, will it still export at lowest nett or would it be able to export 12-5 =7kw =2.33kW per phase? Loaded question but which is the “best” hybrid in that size class - must have a phone/browser app for remote settings and monitoring?

If I had decent roof space at my house, I would go almost-off-grid: council supply goes to a new small DB that has a plug for just in case next to it and the only other breaker is a battery charger that can be managed by data signal relay. This council connection is 20A, so carries the smallest basic fee if any at all. That gives you about 2kWdc charge capacity if ever needed. entirely separate from council is the old DB running off battery inverter. In effect the battery is pure isolation from grid. It normally charges from solar input to battery inverter but if needed a relay allows the grid connected charger to also charge the battery. All your house loads sit on this DB. Because impossible to export, the NRS size limit on solar does no apply. Obviously must still comply with electrical and building safety rules & regulations, but none of the other stuff. Why not completely off-grid? Most council bylaws allow them to charge you for there being a connection available, even if you don’t use it. This way you get some benefit from the small connection - that 2kW charge can help a lot in bad solar times. When I sell my house I will build a single floor home with the right roof to put up a LOT of solar. My current house has awkward roofs and is too big for my 8kW of solar.

The guys that have their own teams sit with sunk labor cost. So better to charge you R10k for labor next week even if normal would be R30k, because then at least cut sunk cost by R10k and help from product margin. Other reason might be who bought at what prices, but an astute vendor would price based on the market and what can replace that inventory at.

What is your source water to tank? Rainwater off roof, river water, borehole water, sink hole water? I have system for river water that can vary immensely in quality that affects particulate filters very quickly. Even borehole water can vary, but far less. Eventually the sources go to unpressurized JoJo. You need a pressure bladder between that reservoir and the house demand. Depending sophistication it can literally be a 200 liter water capacity in a pressure vessel with a gauge. When there is no demand on water, you pump the bladder to required pressure. Your pump controller upstream of the bladder is set to run in a range. So it might kick in at 2.5 bar and run until 4.5 bar. Don’t go tight or that motor will die early doing start-stop-start-stop whenever Aunt Maude brushes her teeth. For me, if somebody does a quick open close like rinsing a few cups or maybe better flushing a toilet, pump should not kick in.

Steve, we started process in early 2023, the documentation then did not indicate 1250A breaker in 500kW bypass then (just like it incorrectly indicated not only the generator integration operation and the free space needed around isolation transformer but luckily my bunker could deal with that). The RFP respondents were all large professional installers (over 200 professional electrical engineers including panel members on NRS) and all had to calculate and specify cables for distance between my LV room and my smartgrid bunker, for me to do the underground trunking in advance.

Coulomb : as I have it there is no power factor ‘downstream’ of the rectifier as it is DC. I am not sure as what good/bad power factor the rectifier presents to the generator on the upstream side, thought it would be 1 from perspective of the gennie. After the DC level, the power factor are a function of my loads and inverter and impact of solar. The financially relevant at the 11kV meter before my transformer is nowadays very good because I switched my old PFC back on after PCS presented 0.6 PF at 11kV level. If generator is AC coupled, I normally have to relay PFC equipment off. Going generator:rectifier:DC would mean I can leave my PFC on while generator runs.

If you know what your power profile will be, I’d do it now while can get that small residential tax help and installers are hungry. Also, council process could take months. BUT since you are in theory conducting a business while renting it out, you might actually get the big 12B deduction (125% on total). Scheme ends 28Feb

I didn’t want to make this thread about my bigger and more complex system. For home / small business I figure Gennie:Rectifier for DC supply would allow smaller and less fancy Gennie, all of it automatic no bounces no ATS and virtually any battery inverter will cope without delving into layers of settings or whether it has a Gennie input. Need a SOC trigger at say 30% and another signal at say 75% SOC and that is all. Whether grid is off or comes back on, run that 45% at constant output Gennie very efficient. Pick rectifier output size at the Gennie happy point, done

Atess sent people from China as they had several issues with replacing their PCB and firmware until things worked. Atess did the job of painting a bad name all on their own! early warning for people on 500kW bypass cabinet. They ship with 1250A breakers so if you planned on 630A cables, dig an extra cable trunk now. Mine also arrived ex factory with the PCB from the smaller one - think 350. Several daughter board components replaced and several shielded cables replaced. From EMS and PPC we manage solar so that if grid is off, the solar follows loads from when battery is I think 95%. When grid is up, we run solar full speed always as we can export to own 11kV transformer. When their Gennie solution showed itself hopeless, I was going to do what hundreds of sites do every day in SA : run Gennie sync locked onto load busbars. DeepSea 8610 controller I think it was will manage the sync and govern the Gennie at fixed output. Atess won’t sign off they can cope… So hence : I go Gennie : Rectifier : DC combiner with rectifier presenting fixed load to Gennie. I will therefore have PCS, Isolation Transformer, Bypass Cabinet, Gennie, Rectifier, BESS, Solar and Grid. another warning : Atess power factor correction is virtually non-existent. Maybe they assume you have a brand new factory with VSD on everything so almost nothing to manage. They said they’ll sort PFC and we must rather disable mine. Under high charge state my measured power factor at 11kV transformer was 0.6! When your payback is grid capping, it does not help my 90kW cap = 145kVA at council!!! I solved that by switching my 1MW worth power factor correction back on. Short debate between my 10 beer keg size capacitors and their two 375ml soda can capacitors The system generally DOES work. It keeps within about 8% of my grid demand cap. I set 90 they might do 95 over half hour measure, so I learnt I set to 86 if I really want 90. Transfer during loadshed is now virtually not noticeable, which is wonderful. it would be nice if there was a Watcher (me doing that manually now). Give it general parameters/goals and then it will figure out that we could run 10kW cap today because solar forecast looks great. When loadshed becomes an issue again, the watcher operates more carefully.

Well, no. I had a very precise RFP. four different large professional installers all ticked the same Yes Can Do boxes in RFP. Probably because Atess manual says explicitly that it can do what was specified. Atess in writing confirmed the manual had an error in translation. (that can run Gennie and Grid concurrent). in their model, if Gennie running: 1. We have to via EMS and PPC keep solar going. They can if you have their solar charge controller (my solar predated Atess so wasn’t going to change that) 2. When Gennie running two parameters are key. One is max generator kW. So say 345kW for my Scania 420. The other is charge rate under Gennie which is a STATIC number and you basically have to, unless have a Gennie double your loads, pick a small number. So because my loads can go 300 : Atess can only charge battery at 45 whether there is 150 solar plus 345 Gennie minus 300 loads or 100 loads or even if I disconnect loads. I need 300kWh recharge so 7 hours of the Gennie… That is pathetic in any language. 3. When trigger Gennie, the two contactors in bypass cabinet kick to open grid and close Gennie. Then opposite on way out. The surges in that transfer are so bad I lost Aircon PCB and Chiller power supplies PCB. there is a lot of the Atess that works great. Their generator integration is a mistake they will have to fix if they want to play in smartgrid game.

It’s really not that big an issue and we have NRS that limit capacity export. The variability in a minute of my solar is LESS than the variability in a minute of my loads. The grid handles fine my loads ranging eg between 200 and 250kw in a minute, it handles exact same way, my solar export ranging between 200 and 250 kw. As long as users stick to decent equipment and connect correctly, distributed generation actually IMPROVES the distribution grid because we help lift voltage in the street. When they get smart, we will get to stage where I only export in peak time of use when they have a big need but then they need to pay me properly. Then I’ll export from battery a constant kVA value. There are far too many people spreading doubt, uncertainty, fear. Usually those councils that don’t like losing revenue, or people selling solutions that need to pretend things are difficult.

I don’t get that part about rectifier lower output voltage? Eg in my case the DC connection is 750V but the really critical part is that each cluster BMS stops a module in that cluster if a cel in a module exceeds I think it is 3.55V. In a home setup the supply to BMS would be about 52V (?) and the BMS then handles voltage per cel and balancing. I’m a bean counter not electrician, so on thin ice when it gets to BMS

Agree on keeping the BMS in control! Most small generators in homes or SME are themselves dubious quality and/or difficult to integrate seamlessly. I like how the rectifier route is seamless on the AC in terms of no possible interruption, and the rectifier can sit as constant load on generator hopefully at its efficient output level until battery gets to target and then stop.

I get what you mean, but in reality not needed. Simplistically, view it same like you have a 15kW system but only 9kW of solar. My rectifier capacity needs to be close enough to load to be able to at least slow down my rate of battery discharge (if grid down and solar is almost nothing). In reality my loads are in any event mainly daytime and my solar is 150% of loads so even cloudy day I have SOME solar. Ideally, I have my grid capped input, solar input, gennie input, load output and the balance is either charging or discharging.

Great! I’ll try them for sure.

Atess have a 300 rectifier as well. I have Atess PCS, isolating transformer and bypass cabinet plus IES battery and a lot of solar, then grid and generator. So an AC coupled smartgrid. Most all is perfect. My use case is grid throttling because I get screwed R440/kVA for peak half hour kVA in month. I throttle grid at 90, loads reach around 300 but solar and battery takes care of that. All of this now works fine, though had to EMS and PPC to make solar and exports work safely as Atess can basically only work with Atess solar gear. I need solution for when have bad solar, maybe some loadshed, battery getting low and need gennie to help for a while. My problem is Atess’s idea of generator integration is a COMPLETE JOKE. (1) despite what the manual says it cannot run grid and gennie concurrently - apparently a translation error in the manual where it says those three lights will be on when grid and gennie supplying. (2) when gennie running, Atess switches to fixed kW battery charge rate - really, no jokes (2) the contactors in bypass cabinet to change over between grid and gennie are so bad that it blows PCB of aircons and chillers (3) standard way Atess cannot run solar during generator. They suggested I ugrade my 420 Scania to 800 😕 They are afraid of the obvious method : run sync mode gennie output to my load busbars. Harolds guy told me it is anyway not possible to sync gennie and AC (even though hundreds of thousands of people do so every day). That leaves me with take gennie output away from bypass cabinet, send that to rectifier that then supplies DC to the DC combiner. So I can run gennie 300, grid 90, whatever solar I have, handle loads and then the rest charges battery subject to my own 300 max charge rate, get to 75% SOC when gennie stops. So in essence a hybrid of DC and AC coupled smartgrid.

Thanks - I want to keep charging / discharging control under the BMS and PCS. My worry with a battery charger is it then messing with the BMS. So just pure DC supply whatever kVA until get signal to stop gennie.