The Solar Thread

Hopefully shortly be joining this thread after watching for a while. 6kWp array on SSW 45 Deg roof and 10kWh battery being installed today.

Slight thread diversion but on solar diverters. The diverters I have seen seem fairly basic. Is there one out there that had functionality like this.

Multiple circuits with preference of use and load optimisation. i.e. Preference for circuit 1 (immersion 3kw). but once not daring any power go to circuit 2 (heater on landing 2kw). Also option to load balance e.g. we are exporting 1.5 kw, circuit 1 and 2 have been satisfied so swap preference of circuit 3 (2kw) and 4 (1kw).

Basically multiple channel highly configurable. I know roughly how I would make one but its quite a task and wondered if one was already available.

Not sure how happy you are with programming and stuff but have a watch of this video….

Otherwise not sure which ready made devcies do what you want. Maybe the MyEddi?

Not sure how happy you are with programming and stuff but have a watch of this video….

I’ve been doing it for nearly 20 years and some electronic stuff but I am definitely not happy with it but that’s due to a slow mental breakdown rather than any lack of technical ability :).

Video link looks good thanks. I have an idea of how I could do most of it but was interested if there was something off the shelf to avoid the work! Amazed at how basic most of the ones I have seen are. I’ll check out that edii one.

The Eddi and Zappi work by diverting excess export to a pre-determined path. I don’t have an Eddi yet, but the Zappi picks up when there’s excess and then starts charging the car when the value exceeds a certain excess. The car can only charge at 1.4kW minimum, so you can chose a % value of that 1.4kW for excess. Anything below 1.4kW and it will draw from the battery/grid to supplement the excess solar gain. The eddi sits in between and diverts to a heater first, then allows the car once the temperature of the heater is reached or the timer kicks in. You can scale the energy, but I’m not sure how much you can split or if you can have a second channel…

Can anyone suggest why my battery charging rate might be topping out at 3.8kW when the system is rated to 5kW on the DC side for charge and discharge?

Can anyone suggest why my battery charging rate might be topping out at 3.8kW when the system is rated to 5kW on the DC side for charge and discharge?

There will be two different limits – what the inverter can push into the batteries and the max load the battery pack can accept. Eg We have the same system as a neighbour but we have two battery modules and he has one. The same inverter can charge ours at twice the rate as his ie the battery pack is the limiting factor in this case.

I know each battery can accept at least 4kW as I’ve seen it do it, but somehow, now the splitter is in place, it seems to be hitting some kind of limit.

My initial thought was resistance in the cables, but I’m not sure that makes sense. The cable run to Bat 1 (12kW) is 2.5m, to Bat 2 (7kW) is 4m. Originally, the cables to Bat 1 were just over 1.25m… BUT, whilst the run to the splitter is now 2.2m, the power after the splitter is much lower…The cables are the right 100-120A spec.

What is the ‘splitter’? An active device or just a cable join?

Maybe that is the bottleneck….

Its an active device called a RESU Plus from LG.

Well that would be my suspect, it all worked fine before you added it…

A few m of cable won’t make any difference (unless you used 3A lighting circuit).

25mm2 4AWG pure copper cable, so no. It also shouldn’t be hot enough outside to cause issues.

Is the “splitter” getting hot?

That’s what I was considering. At those moments, it might have been be in direct sunlight, but equally, it’s only 4 degrees outside and it’s bolted to a sodding great big freezing cold wall.

from Page 35 of this doc: https://lghomebatteryblog.eu/wp-content/uploads/RESU3.3_6.5_10_PLUS_Installation_Manual_ENG_Ver2.3_181030.pdf

It just looks like it’s a passive device, just a copper bus bar with some connectors…

Resu Plus by Ben Freeman[/url], on Flickr

So can’t see how it would affect things unless you have a poor connection or one battery is switched off?

No. There’s a circuit board with power 12v power connectors and 4 RJ45 connectors that sit on top of that 48v coupling.

I assume that’s just an Ethernet switch which allows the two batteries to talk to the single charger…

Is it possible it was cheap and on eBay because it was broken ?

I would try using a normal ethernet switch as if anything is going to be damaged it’s that.

The 48v bit is unlikely to be damaged or if it was you would see a break where one of the connectors has snapped off the bus bar etc…

Do you have an interface where you can see system alarms etc?

It might have a fault code somewhere which will help diagnose what is going on?

The RESU Plus Connector was brand new from Segen. The battery was also brand new, but from ebay, but actually from a solar provider near Rochdale. The BMS showed no charge/discharge cycles. I’ve just looked at the inverter which is the only place you can see messages from the battery and there’s nothing to suggest a fault. The BMS is stating that maximum charge/discharge is 91.9A, which is less than the 100 i would’ve expect, bust still doesn’t equate.

I’ve e-mailed LG – hopefully they can help.

Both batteries did fully charge today taking in 15kWh whilst already having just under 4 in the packs, so it’s working right from a capacity and management POV.

My 5.6kW PV array is surpassing itself… Interestingly enough I had only set the graph to max at 6kW. I have upped it to 7 so see if it goes even higher…

Nice. I think we’ve peaked at 5.8 from our 6.3Kwp array so far. Having a mixture of 100% own power days and 60%ish on the duller days. The app for our car charger is currently screwed due to a software update which made pushing the excess into the car harder as I couldn’t reduce the charge rate. Elec meter is also stuffed so not getting credited for export.

Rj45 could well be a serial connection for commissioning / firmware updates as much as a ethernet one. If possible wee what chip it is connected to.

4.8 is. A new peak for me for a 4.14 system attached to a 3.6 inverter….

@daffy Only saw your post today. Your battery charge rate will have likely been capped due to the temperature (too cold).

We are also capped on a 3.6kw inverter however it is nice to see that the battery charges at a higher rate as it’s all on the DC side. Not so good is the lack of battery control as mentioned earlier in the thread (solaredge battery). It’s a moot point till the meter works and we can move onto the over night tariff.

I wonder if you can have a car charger or water heater on the DC side. That would be ideal for absorbing as much excess as possible.

@flaperon the temperature (of the battery at least) isn’t the issue. The battery has been happily discharging at 5kW even in colder periods.

There’s something in either the RESU Plus or in the paired batteries that’s limiting the current to exactly 65amps. That’s why it can be 3.4-3.8kW as the battery voltage varies.

The next time we have a VERY sunny day, I’ll experiment as I’ve now got a spare comm cable that I made to bypass the RESU PlUS, so I can check each battery independently.

Whilst charging and discharging is a pain as it’s now a little limited, the extra capacity has proven worthwhile.

Thanks to a sunny Saturday and moderately sunny other days, we’ve now been effectively off grid for 4 days. 10p with of electricity used, but almost 50kWh actually used. The extra capacity has helped get us overnight or acted as a buffer until decent gain the following day.

Question for Octopus smarties – how do you tell what energy you’ve exported? I can’t see obvious option on the meter display thing or website.

My 5.6kW PV array is surpassing itself… Interestingly enough I had only set the graph to max at 6kW. I have upped it to 7 so see if it goes even higher…

I was going to post the same, our 3.8 kW system is regularly peaking at 4.25 kW…

4.25 kW by Ben Freeman[/url], on Flickr

I had just assumed it was a reading error in the Huawei firmware, which seems to update itself almost every week….

Question for Octopus smarties – how do you tell what energy you’ve exported? I can’t see obvious option on the meter display thing or website.

On their app:

Exported Leccy by Ben Freeman[/url], on Flickr

Thanks. I have the app now but it no show me that. Only just had their smart meter installed so maybe will take a little while to link up.

Only just had their smart meter installed so maybe will take a little while to link up.

Several weeks in my experience and it still thinks I have two gas meters with the same serial number, but only populates one of them with data and keeps asking for manual readings for the other…

Interesting video about the new Octopus Flux tariff here:

Includes a handy modeller to estimate your own benefits.

I had ignored this tariff and continued with Eco7 which suits us at the moment but our battery/inverter manufacturer has recently updated their software to allow forced export/discharge which it hadn’t previously. Bit of a game changer.

@flaperon the temperature (of the battery at least) isn’t the issue. The battery has been happily discharging at 5kW even in colder periods

the new battery or your battery system ?

I have 2 batteries – one works down to 0 the other has a huff and throttles back when below 10.

Apparently I need firmware update on my slave battery. My installer may have only updated the master on install.

Apparently I need firmware update on my slave battery. My installer may have only updated the master on install.

I registered myself as an installer, then migrated my system over to my own sub domain, so I have total control eg updating firmware when I want etc.

Our installer was excellent at the physical install but self confessed IT illiterate, so couldn’t answer any of my questions, so I just decided it would be easier to take over myself and Huawei were very obliging…..

I’m still a little wary of forced charge and discharge as they will significantly increase wear on the batteries and some battery manufacturers specifically state that their warranty does not include continuous grid charging.

My batteries and the RESU Plus are on the very latest firmware. The batteries individually will charge at 5/5 (98>100A) for the RESU 12 and 4.2/4.2 for the RESU6.5. This has been tested. The problem for some reason is with the RESU Plus or the Inverter>RESU plus interface. We’ve had several days now where the external temperature has been in the teens and it’s made no difference.

I kinda assumed that since the Inverter will only output 100A or 5kW, that each battery would then charge as a percentage of that output and since the bigger battery is essentially twice the size, it would get 2/3rds and the smaller one, 1/3rd. Certainly when charging, unless the gain is VERY low, they both charge and then discharge together. Hence, even though the smaller battery has a lower max charge/discharge rate, in the combined system, it wouldn’t matter as it would never actually use peak charge or discharge rates.

Is there an issue with a house with a perfect east – west at low angle (@20*)? The ridge runs due north -south. I am assuming the losses in winter would be really significant, even if both elevations had panels?

@ Daffy. That’s interesting about the zappi and Eddi. I guess they are like the Solar iBoost device.

My situation is i’m technically inept, I have a 3.6kw system with no battery which is fairly ineffective (12 panels, half on either side of a East/West valley) on FIT. It’s about 10yrs old and never had any funky bluetooth app etc so no real idea but being quite a power thirsty house I’d imagine even on the sunniest days we’re not really generating much more than we use but like I say that’s a guess.

My wife would like to switch the hot tub back on so my thinking was get a diverter that somehow plugs into an external submersible heater, and ideally something that connects to the immersion heater. Happy to pay for install but really don’t want wires running all over the place so suspect with the minimal anticipated payback i’d be better forgetting the whole thing, cracking open a beer and just enjoying the hot tub as it burns large wads of money.

Anyone got any views please lol? (maybe that I’d be better spending money on adding a battery to my set up)