Richard Mackay

There must also be the claim that 'transformerless' is more efficient? (i.e. no losses primary/secondary windings)

I have never had to drain lead acid batteries before recycling them. They simply weigh them as is and you are paid out on this weight..

Have you contacted your building insurance company?

Heat pumps use a third of the power that electrical elements consume. That is a substantial improvement. With that capability I would assume there would be more users of heat pumps.
Sure there are the solar heating options for water but in the domestic environment they are not ideal since much hot water is used at night & early morning before the sun gets going. That leaves one having to store this energy by keeping the geyser from losing heat. My experience with this has been disappointing. (with geyser blankets etc.)
Heat pumps have the advantage of producing the same heat (for a fraction of the electricity used) as an element any time of the day. So one doesn't have to jump through these hoops.
I have had no experience with these appliances. Clearly they are not simple and expensive. But are they??

that is incorrect. The diodes will bypass the shaded panel/s and the string will now operate at a lower voltage. The output from the unshaded panels is not affected. The problem is, that without a good shadow management the inverter will not find the correct mpp and as a result operate the string at the wrong voltage. Another problem is, that the voltage of the string might fall below the inverter minimum operating threshold. This is why long strings (if some shading occurs) are better than short ones.  

I don't know of any RE books but I suggest you find people who have installed systems. It's not too difficult: have a look for houses with PV panels on the roof and go knock on their door. Most people who have installed systems are happy to talk about them..

Take the suspect panels down and set them up on the ground.
Measure the volts of each panel..

What I've commonly seen in the field is faulty connections so before removing the panels completely I would suggest doing an inspection on any joints and then testing the cables from the panels to the inverter. If no problems are found then test each panel individually.

Good idea! 
I'm not impressed by inverters/UPSs . Too often these are seen to be the answer (after one has given up on the generator option!) But they always seem to disappoint. Way back I also thought that by installing a couple of batteries and an inverter I would be able to keep essential stuff running at my house during power outages. Well the batteries died and then leaked acid in the house so I didn't feel like rushing out and buying another set!
After pondering this universal disappointment that we end up experiencing I concluded that a lot of the backup power solutions are inefficient: e.g. What has made the laptop PC such a success over desktop PCs is not only that its portable but that it can run for hours on its own batteries. It can do this because the manufacturers have done a fine job of creating an efficient package. (If you don't agree with this then do a test of comparing a UPS powering a desktop vs a laptop PC)
This prompted me into developing low voltage backup solutions. The product I make is a low voltage backup unit for broadband internet routers. It works like a charm and keeps your internet going 12hrs (see small print..) but is head and shoulders better than a UPS/inverter solution.
I know nothing about solar driven pumps but as Phil has pointed out maybe these are way more efficient than the AC option and offer a much better solution, even if you have to make a plan to get it to pump at night??
 

Faced with the costs of "Wonder Gadgets" to heat water from excess solar availability, I have come up with a different way of doing it....
I have already had, for some time now, a raspberry pi hooked to my inverter monitoring and controlling various bits and bobs around the place...
One of my greatest frustrations is the "lost solar" power that is often available during the average day.... This hot water system but one small addition I have made to try and utilize this unused power.
I put in an order to a local (EL) company for a triple 220V geyser element. It wasn't as pricey as I expected. The 3 elements are 500W/750W/1000W respectively, all on a single screw in, standard fitting (with an extra long thermostat pocket as well, which reaches well beyond the ends of the elements.).
The long and the short of it is, using my pi/mqtt/fabricobbled system, I can get a pretty close estimate of what inverter/solar power is available beyond the immediate consumption at any given point in time...
Using a small "Sonoff" wifi switch, hot wired to a quad 10A relay board, a bit of Node-Red and some head scratching,  the net result is, well fantastic!
If there's 500W excess available, turn on the 500W element... Same for 750/1kw.... Need more? Turn them on in combination, to step in 8 steps, 0W to 2.25Kw  as needed... The extra deep pocket for the thermostat got a Sonoff with a DS18B20 temp sensor to feed info back into the mqtt as well.... (Yep, you can series the elements as well with a bit more head scratching to lower the wattages still further, but lower than 500W is a waste of time as I have found out...)
Safety? Sure... Using the existing Thermostat pocket in the geyser, there's a good old fashioned clicky-clicky rod slotted in... Hooked up to the common neutral of the 3 elements... If he's unhappily hot, everybody shuts down...
And... It works... Well!
Total cost of the additional bits was less than ZAR1K, its been running for about 6 months now and barring some really crappy weather, the household of 4 has used very little gas in the geyser system over the period...
Cheerz...
E
 
 

I am not sure what the regs require, but my install has a separate galvanised pipe and sprague for the panels' earth conduit.
 

Hi Gremlin and all
Think this following link explain it clearly as well.
https://solarpanelsvenue.com/mixing-solar-panels/

What power (current) are you needing to feed?

Have a look at this discussion: 
 
 

Refrigeration is often overlooked or ignored when looking for energy savings.
 
Cleaning the condensor and/or improving air circulation around the fridge can reduce the energy it consumes by 20%... or a lot more if it's a commercial underbar type fridge. Ive seen up to 40% energy saving with condensors being cleaned on commercial underbar units. Even domestic fridges have small condensor fans sometimes, check they're working and dust free.
Check the door gasket for damage and replace if necessary, also angle the fridge slightly backwards so the door has a better tendancy to close on its own.
Use your cellphone to check the internal lights switch off when the door closes.
If you fridge or freezer needs manually defrosting do so regularly, don't wait until there's thick ice built up inside it. If it needs defrosting more than once every couple of months check the door gasket and the door hinge adjustment. I've seen old fridges where the plastic washer in the hinge has broken and fallen out causing the door to drop down about 5mm and leave a thin air-gap along the top of the gasket when the door is closed and most people wouldn't be tall enought to notice this.
Check the temperature isn't set too low, if it is then thermal losses through the insulation become excessive. Don't use glass door fridges unless you really have to, they have higher thermal losses through the door than a regular fridge. If the fridge feels cold on the outside of the cabinet or it has areas on the cabinet where condensation forms, assuming the internal temp is correct then get rid of it (preferrably check it with a thermal camera if possible). Always buy a fridge with a minimum of A++ energy rating. I've also seen chest freezers where the thin aluminium internal liner has become damaged by frozen food being dropped inside it, this led to the foam in the base area becoming water logged and losing its insulation which in turn meant the compressor was running 24/7.
Locate fridges and freezers in a cool and ventilated room without direct sunlight.  I've seen a 30% energy saving where domestic fridges were in a small room with polycarbonate roof and direct sunlight from big windows and they were moved to inside the garage where it was much cooler ambient temp. This will also enormously  improve the compressor lifespan.
There's an urban myth that says it's not good to turn fridges off. I'm guessing it's because if a fridge has a slow gas leak it might leak quicker if the fridge isn't running. Ignore it, if you have a fridge that's empty don't leave it on to unnecessarily consume energy; rather run one full fridge than two half empty ones. On the one in a thousand chance your fridge does have a gas leak it will already be highly inefficient and needs fixing or replacing anyway so you've got nothing to lose in the long term.

Further to this.

I see MANY rooftop installations where the installer has mounted the panels less than 200mm from the roof surface. These panels generally overheat and will deliver sub-par performance.

Most of my installations are free-standing so that the air can circulate freely and the panels stay cooler.

Thanks Richard, OK then I'm going to blast it with the compressor.  I've finished brushing the components with a dry brush.   Afterwards I will leave it for about an hour in the hot sun to dry out.

Agreed. 125 V should be OK, but the SCCs seem to run hotter with high voltage like that.
The fact that the shutdown only happens when the inverter is working hard for a long time suggests a thermal issue.
Consider flipping the fan direction; it helps with cooling. There should be a maximum temperature recorded somewhere. If you use fully patched firmware (e.g. 72.20e if it's not a 64 V model), you can see the temperature on the LC Display.

I suspect that heat is causing the inverter to shut down (if there isn't an overload condition)
Try cooling the inverter with a fan (any fan). Get more air flow through the inverter and see if that makes a difference.. 

You can go for an inverter as you have indicated but these are not very efficient. (i.e. Using a low voltage battery to generate 220V only for that voltage to be reduced to the battery voltage again)
What you could try is to use a power supply for your PC like this: https://www.powerstream.com/dc-pc-48v-1200w.htm
So with only a battery bank (don't use 12V!) of 24/48V you could keep your PC going for longer by comparison. You will also need a charger..
I don't know if your monitors have external power adapters but if so you can power them directly from 12V (which is their typical supply voltage)

I just have one very bad part of me and I talk better to computers than humans.  But I will sit and draw my system on a sketch one day.   Rebel I am fir sure.

The council every two/three weeks came to inspect my house for what I was doing but in the end they got tired.  😇 I personally believe in time to come we all will only have low voltage DC homes with a few sockets AC. That is if we have leaders and not followers which seem to be so common(algemeen).

With the dry contact set to 51v on and 50v off the geyser will only run in this range. If any other large load example the oven is on then the oven will receive priority, the geyser will switch off.
If there is not enough solar power the battery voltage will dip below 50v and the geyser switches off automatically and will not drain the batteries. 
We're running off grid, this voltage range works well with our batteries and system. 

No I will just add panels to my existing solar setup. During Winter I have enough power to heat the geyser. Summer time we run a pool and will need an extra 750 Watt for a few hours a day. The geyser was done a few years before the solar. The EV system has too much maintenance. The water pump failed this week. It also melted the insulation tube covering the copperpipe on the roof. The pipe was at 144° C when the pump failure was discovered. 

Hi Getskay
What type of USB extender are you using? A normal USB to USB extender is limited to 5m as explained by Richard.
The extenders that use lan cables can go up to 50m. I do not know how good or reliable these are.
I see you can cheap and expensive versions of these extenders.
I have not tried them personally.

OK.... so the solution I have for now is to run my Goodwe on the 50Hz Grid Default setting rather than the "South Africa" setting. Goodwe tell me that under the latter the inverter will disconnect at 195 and only reconnect at 200. They recommended the change to the default setting. I discussed this with the installer and we'll see if it improves stability. However there is a warning that some some "protections" on the system will be disabled. Too much for my tiny little non-electrical mind. So we made the change and we'll observe.