Gary the Bat

Thanks Gary & Pho3niX...
I did give the gears a good dosing of white lithium grease when I put it together, but it could probably do with another dollup.  I've got some sticky backed acoustic foam somewhere, so - if I can locate it -  I might try sticking some of that to the back of the board to dampen it a little as you suggest.  I could also have taken a lot more care in making the gears!  But really, the noise isn't a problem for us.
The new 'LED flow meter' project will be completely silent, though.
I think I've settled more-or-less on how to do it...
A 3D printed 'frame' - essentially a strip of plastic of whatever shape and length with a slot the width of the LEDs (5mm) in it.  This is laid face down on a silicone mat, then hot glue fills the slot.  Before it sets, another (previously prepared) 3D printed part, the same shape and size but with individual holes for the LEDs (rather than a slot) filled with the LEDs is pressed into the glue.
The idea is that the (set) milky-white glue acts as a diffuser for the LEDs, as well as holding it all together.
Here's a test piece I made up with 8 LEDs to try it out, just running off an arduino:  https://sendvid.com/5ay3wpud
I think I might try making the glue a bit deeper, so as to increase the diffusion effect.
For running the LEDs themselves, I looked at 3 options.  Neo pixels (individually addressable LEDs) would be cool, but aren't that cheap, although they might be easiest to work with - especially for wiring.
I2C port expanders (PCF8574 etc) would do the job, but again, not that cheap and I would need a few.
The there's the 74HC595N 8-bit shift registers...  I have loads of them already, they're cheap as chips (heh) and I can cascade them as much as I like.  So that's what I'm going with.  They need 3 pins (clock, data and latch), but I think I can get away with sharing a single clock between 4 of them (or rather 12... 4 channels of 3 chips, 24 LEDs on each channel).  It will take me into unfamiliar territory as far as coding goes, which isn't a bad thing.
Both of the above last two options lack the ability to dim individual LEDs (well, except the 74HC595N will if you want to use a special library which interferes with all sorts of other things), which is quite important if I don't want the thing to look all 'blinky' like a '70s star ship.  A smooth transition between adjacent LEDs will make it look more 'flow' like.
So the idea I (and likely thousands of others, if I searched Github) hit upon is to have two negative 'buses', with alternate LEDs connected to each (so no two adjacent LEDs are on the same bus), then I can use PWM on the negatives to have one getting brighter, while it's next door neighbour is getting dimmer.  This way I can control the intensity of as many LEDs as I like, but only use 2 of my precious PWM-capable pins (per 'line') on the ESP.
The two PWM pins ramp up and down, but opposed (one is going up while one is going down) at a rate proportional to the rate the LED 'positives' are switched on in sequence (only ever 2 on at any time).  So LED 1 is turned on and ramps up, then LED2 is turned on and ramps up while 1 is ramping down, 1 turns off, then 3 is turned on and ramps up as 2 ramps down and so on.
You can see this principle working in the video above (8 LEDs), or a little better in this one (24 LEDs): https://sendvid.com/gddno1tj
I'm quite please with that, but if I can figure out a way to do 3 PWM negative channels (x4), so have one dimming, one on and one ramping up, all the better. 🤔😁
Anyway, have a good Christmas or whatever you're having.  Comments/suggestions most welcome! 🙂

Vital to being able to keep within the inverter output limits (and avoid importing expensive grid power unnecessarily) is having the means to display the relevant information in an immediate and accessible way.
That's what I told my wife, anyway.  Really, I'd just scored a bunch of old RC servos on ebay for £5 and I wanted to play with them. 😉

 
In context:

 
It uses 6 servos, a Wemos d1 mini clone and a tri-colour LED.  Dial faces are 3D printed, with a filament change from white to black (which turned out much better than I imagined, TBH).
The servos only had around 90° of sweep angle, so I 3D printed some little holder/gearbox things to get over 180° and provide a shaft for the needle to go on, plus some 'steampunk' needles.


 
All run buy the obligatory D1 mini and held together using the very latest in 'twist and tape' technology.

 
Yee-haw! 🤠
It gets fed the data from 'node-red' running on a Victron CerboGX via UDP packets over WiFi, updating as often as the data changes (approx 3 second intervals).  The LED changes colour according to state, so 'All OK' is green, 'You're getting very close to/exceeding the inverter output limit, so if you don't want to pay for grid, don't turn anything else on' is red, then blue for 'dumping power into the hot water tank'.
It's by no means silent in operation.  I originally made a single-servo version for just PV generation and coded it so that the meter movements were gradual (a kind of PID to get from one value to the next), but apparently it 'sounded like we have cockroaches' when it made it's ticky-scratchy transitions between values, so the big version just jumps between values with a 'zzziiiiiup!' sound.
It's actually quite reassuring to have an audible indication when the sun comes out for 5 seconds, or it starts charging at night.
I'd also put a little radar sensor in there, with the aim of having it detect when there was nobody around, so it could stop displaying to save power/noise.  Unfortunately, that meant that every time you entered the room, all 6 needles would suddenly move at the same time, making you jump out of your skin and spill your horlicks, so we just leave it 'on' all the time now.
There's also a basic web UI, so you can see the same data on your phone or whatever, plus it's useful for troubleshooting:

 
I had fun and learned loads making it - and now it's become a family game to try to cook dinner without making the red light come on. 🙂
 
Libraries used are 'ESPUI' and 'servo', plus 'arduinoOTA'.  Code, FreeCad file for the gearbox & stl file for the arrow-head needle are all in the attached zip.
Power_meters_v2..zip

I went off grid for water about a month ago. My borehole is only 37m so you might need a bit more power in the borehole pump than me.
The main thing from my perspective was to get a VSD pump for both the borehole and the booster pumps. These types of pumps have a softer start and therefore dont put a huge strain on the inverter at startup. i.e on startup they will slowly increase their power consumption as opposed to the cheaper pumps that can pull 3x or more their rated power on startup.
This is quite a big deal in an off grid water scenario as every time you open a tap that booster pump runs, so if it spikes and then settles at 0.75kw every time you wash your hands it does put strain on the system. My DAB Esybox booster pump will pull 200W to 600W the majority of the time but can ramp up to 1.1kW if I have irrigation and shower and a tap going.
My borehole pump is a Grundfos 0.55kw VSD, again gentle startup but I also have a smart switch connected to it so that it only runs on sunny days. My tank is 5000l so I can wait a day or 2 easily if its raining.

Initial install was neater, but I added 2 extra batteries + 600amp victron busbar + battery disconnectors after the initial install
wall space became a problem 😂

Initial install was neater, but I added 2 extra batteries + 600amp victron busbar + battery disconnectors after the initial install
wall space became a problem 😂

Initial install was neater, but I added 2 extra batteries + 600amp victron busbar + battery disconnectors after the initial install
wall space became a problem 😂

Initial install was neater, but I added 2 extra batteries + 600amp victron busbar + battery disconnectors after the initial install
wall space became a problem 😂

Initial install was neater, but I added 2 extra batteries + 600amp victron busbar + battery disconnectors after the initial install
wall space became a problem 😂

I ran into the same problem: my 8kW Deye inverter became very unhappy with the generator on the input. So, inspired by PaulinNorthcliff's remark above about 'fiddling with the throttle' I set about finding my generator's speed control, and soon found it, by pushing and tugging on springs and levers (with the generator running) until I found something that affected the speed, and tracing that to a set screw. Then, with a heater drawing a few kW to load it down (directly plugged into the generator, not connected to the inverter yet), I monitored the frequency - it was about 53Hz under load - and adjusted it down to 50Hz. After this I unplugged the heater and flipped the switch to connect the generator to the inverter input. And as PaulinNorthcliff suggests, we set it to draw well below the generator's rated output capacity. Because the inverter presents a constant load, the generator now maintains a reasonably stable speed, and happiness reigns supreme.

I have to agree here - I have 2 x 8kw Sunsynk and I use Solar-Assistant for the reporting, also allows you to control and edit all the settings on the inverters remotely. Very easy to setup.
It integrates well with home-assistant as well, the only drawback is that it doesn’t support pushing back of automations from home-assistant from what I can see. - eg When there is load shedding automatically increase the battery reserve
But hopefully they add it soon

Looks Good - you can get the tubular plastic things at builders - I think I paid R50 for R4m and a couple of bucks for the fittings
The fan is an elegant and pretty robust solution 😀