BenDL

I agree, equipment earthing (or grounding, same thing different words) makes sense & is straightforward. System grounding is about whether to earth one pole of a battery to an earth conductor or not. As far as standby battery installations are concerned I prefer not to earth a pole neither on PV side or on battery side. If you were to earth one pole, you are effectively creating a "first earth fault" which is fine. (nothing happens as there is no short-circuit return path created to the other pole.) Problem arises if you accidentaly create the "second earth fault" i.e. when you accidentally earth the other pole. If you install earthing protection then you may sometimes require one pole to be earthed. There is nothing to be gained by earthing one pole of a DC system other than if you wish to use the earth/ground as a current return path. Cars work that way: you attach the negative pole to the body of the car. (some older cars use the positive pole) But in that case it is about saving conductors as you use the metal shell of a car as the negative conductor.

Thanks for the detailed updates. I pretty much went through this same sequence of events last year, increasing battery capacity, then increasing the MMPT, etc. etc. Putting more & more money into trying to reach that elusive optimal point... Problem we have in SA is that we have lost confidence in the reliabilitu fo the grid & that is really where the hassle factor is introduced as we want to be "off the grid". Although this process is initially enjoyable, one becomes a bit of a power station manager. After a while the novelty wears off. During winter 2013 in my area the grid was quite reliable so you start questioning whether this is worth all the hassle & expense. My learning points were: Payback time on most of these systems is 6+ years, if you do a lot of work yourselves & buy wisely. (<R10/W) The sun doesn't shine 24x7 - Started mid Nov 2013 and the first full sunshine day was 1Jan2014. And even then you really get decent power from 10:00 to 15:00 in Gauteng. Battery capacity is the limitation. Adds expense & yet to see if batteries really will last 5 years. Grid-tied inverter is really the way to go if the grid is realiable - optimal use of the PV panels & use the grid as the battery. (Sure there are issues with City Power...) But munipalities are not very supportive of this - eats into their revenue stream, and all sorts of other excuses.

This looks like a seriously good piece of kit if it all works & is reliable. MMPT built in, on-grid, off-grid. You'll need what, at least 5 x 24V panels in series to get to the minimum voltage for operation? But I would imagine that 10-15 panels would be the norm? Any idea on the price point? Ben

Hmmm, the diagram. Yes, if you have a surge arrestor that will have to be connected to the body of earth. (But the negative pole of the battery is not earthed) What leaves asked: "Should the negative terminal of the battery be earthed/grounded?" I see no advantage to doing this. Ben

If you are talking about the DC side, then you would not ground either the positive or the negative. (By Grounding do you mean connecting to the system earth? Alsorefrred to as earthing?) The schematic provided by Wetkit also does not show any grounding of the DC side. It clearly shows running two conductors from the solar panels to the batteries. Motorcars use negative grounding just to save on the use of conductors - the body of the car is used as one conductor. (Some olde cars used positive grounding, proabably just to be different & to confuse the lawyers...) I hope I have inderstood your question correctly?

My house is also filled with the 12V/50W units & each light has its own transformer (recessed into the concrete ceiling). Gives a beatiful light I have replaced some with 12V LEDs - easy straight swop out. But makes more sense taking the transformers out & going to 220V units. (Transformers are another couple of Watts of losses?) Problem that I have is that all of my lights are on electronic dimmers. If the load goes too low (too many LEDs) the electronic dimmer cannot extinguish fully. So I normally keep one or two 50W bulbs in the cicruit for the time being... (Only seen the warm white which are a good colour - I would imagine the daylight even closer in light colour to the incadecent?)

Well if you have done nearly 2 years without interruption, then you had it pretty much spot on! You think you would get it to work even with half the panel capacity? What life-expectancy are your expecting from the batteries?

Would be interesting to see if you will get through a couple of cloudy days on that battery capacity? I would think not, especially if the batteries start ageing.