Backup power from solar inverters

[@Taki_tam_ktos]

In one video you have explained more, than other people in 50 videos. Thank you! Thumbs up!

[@philldonn705]

Andrew. Great demonstration, you've shown in 3 minutes what was missing to be mentioned clearly in all the Huawei manuals. I think it is important you state that Huawei does not recommend for their inverters to be operated in off-grid mode without battery. In fact they explicitly state that "batteries must be used or output will be abnormal when PV voltage is too low". From a perspective of an electrical engineer I can say that operating the inverter in off-grid mode without battery can put strain on the inverter components when electromechanical loads are operated such as motors. When voltage is low, this kind of components tend to draw higher currents than nominal, which can lead to a strain on the inverter output transistors. Yes the breaker might trip and save the inverter but not in all cases. In case of only resistive loads, such as lighting, I don't think that any issues could occur since the load current will decrease in relation with output voltage. The only issues I see here is that Huawei could void the warranty. On top of that I bet that the inverter has not been tested to work in such conditions and therefore you operate it on your personal risk.

[@solar4ever843]

Hi, thanks. Always good to hear things from the perspective of engineers. I'm sure people will appreciate your insight into the potential for inverter damage if they connect inappropriate loads (like motors) to the backup circuits. We always recommend lights and standard GPOs only with no heavy draw appliances connected.

[@BirdsofEurope]

Judging by that 1 second delay at 1:37 this also requires an uninterruptible power supply (UPS) also in order to keep a desktop PC working?

[@solar4ever843]

Apologies for the long delay in responding. Yes, 1 second is far to long to keep a PC alive so a UPS would be needed to bridge that gap.

[@blablabla3843]

Is it possible to connect all the house to the back up box instead of only essential circuit?

[@mp99utube]

When I first read about the Backup Box I thought it must be providing a 50Hz reference to the inverter as the grid is no longer present to do so. But on probing deeper it seems the Backup Box is just a bunch of contactors that switch things around according to the presence (or not) of grid power. So doesn't this mean the inverter has its own 50Hz reference when the grid is absent? If so, what's to stop a person making their own changeover system, connected to the AC output. That could be a lot simpler than this box if all that person wants is an emergency socket?

[@solar4ever843]

"what's to stop a person making their own changeover system, connected to the AC output." I don't know. If you do it, then please let me know how it went...assuming that you aren't breaking any electrical laws wherever you are. Fronius have a simple 'PV Point' option with their new hybrids (GEN24) that is no more than a single phase 10-12A RCD protected outlet directly wired to the inverter. It's intelligently controlled, has to be configured in firmware, so with Huawei having no such option apart from 'Off-grid mode' enabled for their backup box, I'm certainly intrigued to know if you get something like Fronius's PV Point to work with an outlet only. I'd try it myself but if it worked, then where do I stand with our status as a Huawei premium partner in Australia? Might not be a good look. Cheers Andrew

[@AudioJudgement]

In my area there are significant voltage drops (even saw 180V on my UPS) in some days between 6 PM and 10 PM. I ordered a solar panel kit without a battery. Now I'm wondering if I get a battery, will the battery compensate for the grid voltage drops, so I can have a stable 230V? I have a submersible well pump and it goes into under-voltage protection. So, sometimes I'm left without water, which is annoying.

[@solar4ever843]

I'd be talking to the electrical distributor about meeting their legal obligations to provide power at the correct voltage. In Western Australia its 240V +/- 6% so no lower than 225.6V, but under AS3000:2018 it's 230V +10% or -6%, so 216V minimum, either way, 180V is far too low.

[@MeSimplyMyself]

@@solar4ever843 in my eastern europe country they dont give a * about meeting their legal obligation, so it's up to us to get around them :). I've got similar voltage fluctuations, going from under 160V to over 255V for years. The only solution i got is to use voltage relays to protect my house from getting busted appliances. Now im speaking about the huawei m1 inverter + luna2000 batteries i have. They DO NOT work offgrid without a backup solution. Im owning a backupbox b1 from huawei and it's got a "minor" problem, in that it works as SINGLE phase only offgrid. So if power is out, inverter goes offgrid, all nice, but the backupbox will only provide 1 single phase of upto 3 kW even if you got a 8/10/12 kW 3 phase inverter. What i did is basically use synced 3p voltage relays to cut power to the backupbox and hence go offline while the grid power is outside the inverter supported range of 200-250V. Sadly, due to design of the box that only gives you single phase limited output i run into to a lot of issues like not being able to turn the all air conditioning on at 40 Celsius in the summer. Huawei is dead silent about their 3 phase backup solutions.

[@Ultimate677]

Can you send a picture of the back box with the door open ? I am trying to understand what signals from the backup box need to be fed to the inverter, so it feeds power from the battery.

[@solar4ever843]

Hi. If you Google "Solar4Ever Huawei Review" and go halfway down that webpage you'll see the Huawei B1 backup box open with the components inside. This is a little bit of a 'weird' box though as it is 3 phase going in from the inverter and out to the loads/boards whilst the grid is operating but when the grid fails this backup box only supports the backup circuits on a single phase. There are two wires connecting the backup box to the inverter for comms. (Connections are shown on a linked PDF document near the end of the review page described above).

[@Ultimate677]

That’s excellent information thanks very much. What I was trying to figure was, do you need communication between back up box in order to use capacity from battery if grid goes down. From what I gather it is just to control a simple relay. I have a trip board which I can switch off individual loads so I don’t need a backup box to prevent overload of Inverter. Do you think this set up would work? for some reason when I tried this first changing settings to off grid mode. The inverter stayed on but didn’t switch to outfeed any power from remaining battery.?

[@mehmoodmirani8750]

just wanna know ,does this purely work on batteries during night with grid off

[@MrBsmurfy]

Any issues with safety either this system? Here in ireland there has been a circular from one of the state agencies expressing concerns, i believe due to potential hazardnto workers on downed lines in the event of a power outage. I have just installed this huawei system without the backup box at this point but was hoping to have it installed down the road...Will have to see if they change their opinion or not.

[@solar4ever843]

Safety issues...? None whatsoever. Without the backup box the inverter will simply shut down under the usual 'anti-islanding' requirements. This will protect electrical workers and I can confirm that the Huawei inverters definitely do this, as do every other inverter I've ever worked with here in Australia. With the Huawei backup box installed, it 'islands' so that the selected backup circuits are provided with battery/solar power during the grid outage via a separate cable to the 'backup main switch' while the usual AC supply to/from the main switch is disconnected.

[@MrBsmurfy]

@solar4ever843 yeah that make sense and what I expected. speaking to the company that are due to do the install the state body seem to be excessively cautious. It doesn't seem to have been borne out by incidents but I haven't seen it myself. Hears hoping it gets sorted.

[@Sianda]

Hi, nice installation. I wonder how you connected backup load to the breaker? I mean you have current from the grid and also from the battery on same breaker?

[@solar4ever843]

Backup has its own breaker. Usually we use the neutral position of a three way manual changeover switch for this. Backup supply from inverter/battery to one side, from grid to another side, and middle is neutral.

[@oliverH13]

hi, thanks for the video. Coming back to Shi Yu Meng point. What happens when there is an outage break but I only have a inverter and battery ? I don't get the added value of this box. Or is it only that no power flows back to the grid ? Thanks for your support

[@solar4ever843]

Apologies for the long delay in responding. If you only have the inverter and a battery, and again, talking only with any authority about Huawei in Australia, then when the grid goes down, the inverter will shut off so you will have no power at all from panels or battery. The backup box is needed to provide power during an outage to essential loads. e.g. Max 5kW (21A) from the single phase B0 box of 3.33kW (13A) on a single phase for the existing B1 backup box for three phase hybrids.

[@simonB7046]

Hi, thank you for the video. We've been having a full Huawei system installed this week (solar, battery storage & backup box) here in the UK and today it was powered up for updating and testing. The battery and inverter are installed in the shed with the backup box indoors in the under- stairs cupboard. The backup box has a very loud buzzing which is too intrusive to be in the house. Question is, are Huawei backup boxes all like this or have we got a duff one? It's been switched off for now, until the electrician has contacted Huawei but as you have one fitted, we were interested to see if yours is the same. Many thanks

[@solar4ever843]

Hi Simon, never heard any sound coming from a Huawei backup box that we have installed or my own, so either an installation error, perhaps cables not terminated well, or as you say a component inside failing. The contents of these boxes are really very standard electrical parts, nothing proprietary to Huawei. Leaving it turned off until it's checked seems a wise. Andrew

[@simonB7046]

Thank you very much for coming back to me, really appreciate it.

[@leonleon8675]

I have a house on 3 phase and I will soon have a similar system on a larger scale (HUAWEI 3.68 KTL M1 Hybrid Inverters , 3 x 5 KWh Batteries with Back up Box, 9 x Hanwha Q Cells Q.PEAK DUO ML-G11S+ 505W) Can i have the entire house on essential load? Thanks

[@solar4ever843]

Just to clarify you are getting 3 x 3.68 L1 (not M1) single phase inverters, each with a 5kWh battery and backup box along with 9 x 505W panels? Strange way to do it instead of 1 x 10kW three phase inverter, 1 x 15kWh battery and so the only reason I can think of is the importance of backup to you. 3 x backup boxes 1 per phase with a 5kW potential for backup on each instead of the paltry 3.3kW on a single phase with the larger inverter. The 5kWh battery can only output max 2.5kW , so you will be getting 2.5kW (10A) from each box, per phase. Not enough to power an entire house but certainly ample for essential loads like lights, outlets, garage door etc. If you increased each battery to 10kWh then you would get 5kW (20A) power from each battery which would certainly be better, but of course, it would not backup anything in your home running on three phase. There is a new single phase backup box coming from Huawei called Smartguard. I have no experience with it yet but I don't think it will get around the battery output limit of 2.5kW that you will have.

[@lucasokomuniewski6525]

What happens if you don't have a black out box?

[@solar4ever843]

The inverter will shut down. The backup box is primarily a safety device to protect line workers from being electrocuted. It's first job is to respond to the inverter detecting the frequency and voltage changes of a grid outage and shut down the normal solar supply to the house/switchboard/grid. The official term for this is 'anti-islanding'. In the video I show the solar AC cable coming from the inverter going into and then out of the backup box instead of it running directly from the inverter to the switchboard. This is so it can perform the shut-down. After it has done that shut-down, it then channels battery/solar power to the secondary backup cable that runs to the backup main switch and from there to power any loads on the backup circuits only. Without a backup box there is no safety device to protect line workers, so the inverter has to shut down. Having said that, there are inverters that can send power to an RCD protected 10A GPO usually installed by the inverter, during a blackout without any backup box. Fronius GEN24 inverters have this (called PV Point) and some of the earlier SMA inverters had this feature too. It simply means that the 'anti-islanding' hardware/firmware is built into the inverter to power whatever is plugged into that single outlet.

[@ShutterKnack]

Thank you for this video and the answers in the comments below. It really helped me with my decision and I think I am going for the full Huawei system (over a SMA + BYB system). Much appreciated!

[@denito323]

Hello, how can I contact with you?

[@yellowyarrow585]

Just had a backup box installed - do you find they have a noticable 50 Hz hum? Mine does, just wondering if thats usual or not? I can hear mine from 5+ m away.

[@solar4ever843]

I can't say I've noticed it.

[@eamonsweeney8750]

Hi. Thanks for the video - great to know that. But I have been finding that installers don't always seem to be aware of the back up PV facility where the grid is down. Does it need to be wired in any particular way? I have a full Huawei system: inverter, back up box & 5Kw battery. Also- in an off-grid scenario will the battery also be charged from any excess PV power from the panels ? Thanks!

[@solar4ever843]

The installer only needs to wire the backup box correctly and then activate 'Off-grid' in configuration settings.. www.solar4ever.com.au/pics/offgrid.jpg If your backup currently works from the battery when the grid goes down (you can test that by turning off your main switch) then it will also work directly from the panels if the battery is empty or off. In an off-grid scenario, yes the battery will be charged by the panels. I wouldn't refer to it as 'excess' PV power as there is never any such 'excess' in reality. The inverter entirely controls the panel output, pulling down only exactly what it needs for the battery, loads and export, subject, of course, to sunlight and available power.

[@eamonsweeney8750]

@@solar4ever843 Brilliant - thanks for that Andrew

[@davidmcgettigan]

Is the “backup loads” output from the backup box always live? Or does it only become live in the case that the grid power failed? I’m confused as to how you are powering selected circuits in your panel; but not all the others (back feed).

[@solar4ever843]

Hi David Yes they are always live - otherwise the backup circuits would only work when the power went out which, obviously, isn't good. Basically during normal conditions the grid just flows straight to the backup circuits powering them, during an outage it changes so that the battery/inverter & panels feed them. We run a cable into the switchboard which is the ‘backup supply’. That goes into a circuit breaker labelled ‘Backup Supply main switch’. All the circuits that the client wants to back up are fed from that breaker, removing the feed from the ‘grid supply main switch’

[@MeSimplyMyself]

@@solar4ever843 this only works if your house is built with the idea of a emergency backup circuit in mind, which doesnt happen in majority of cases. And having only one phase of upto 3 kW outputed in offgrid mode is really really poor design for 3 phase backup boxes (b1). If i got a 3 phase heat pump, then what, for example. Or if i need more than the 3 kW the backup box provides, for some airconditioning, or water / heat pump? Do you have any suggestion on what to do on a huawei m1 3p inverter? Ty

[@RobertBensonWobbit]

Hi Andrew, interesting video. Question: What happens to the excess power produced from the panels when the grid and battery are disconnected? F.ex: producing 5Kw and the essential load is only drawing 1KW. What happens to the excess 4KW?

[@solar4ever843]

Panels don't ever produce anything more than the inverter instructs them to. So, if only 1kW is required, then 1kW is drawn down from the panels by the inverter. We are seeing this very clearly with export limiting becoming more commonplace. 10kW inverters, with 15kW of panels, in perfect solar production conditions might only be producing 2kW because house load might be 0.5kW and export limit of 1.5kW, means 2kW is all the inverter will extract from the panels.

[@fastbike9845]

Why is there rubbish in the mains box ?

[@solar4ever843]

lol

[@2Drezik]

Even my dumb installer team coudn't give clear information about this. bravo