maxomill

sorry for the too late reply
I have had good results using 12v 10w flood lights . about 800 lumens
also if you want to shine quite far then eurolux sell a I think 3w 220v led gu10 globe that has 3  1w  leds in it and I've shone it 20m +
cheers

but all things considered    can you not just connect to the bottom outlet then all problems are solved
 

v series inverter running self consumption
20A inverter supply
63A Eskom supply breaker use max  6.5 kw
 0 DC battery demand unless eishkom off
10a charge from inverter
35 A PV max current
0A export but can do 1.2 kw
 cheers
 
 
 
 
 
 
 

It has to do with earth faults (eg a short from the PV cable to roof material for example). An earth fault can cause one fuse to get bypassed, and the system will continue working normally as long as no second fault develops. If you have no second fuse, a second fault potentially causes disaster.
If no second earth fault is reasonably expected, for example on the cabling from busbars to inverter it is rather unlikely as it all runs in PVC trunking with thick insulated cabling, then you don't need the second fuse.
Edit: Granted, if both fuses are on the ground, an earth fault developing at any point before that is not going to blow any fuses :-)
 

The reason I am unconvinced about fuses, is not that they aren't a legal or safety requirement.
Yes, I'm convinced to install them, but I am unconvinced that they actually blow and notify me that I have a circulating current issue.
A PV panel will only conduct in reverse after Voc is exceeded, and at Voc the parallel strings provide zero current by definition.
Now a blown bypass diode could provide sufficient voltage mismatch, but I think you'd still be splitting hairs whether you'd get enough current to blow a fuse in say a 3 string array.
Maybe even a four string array would be pushing it too.
Granted, if there is 1.5X the rating the fuses will blow, I just think the likely-hood of this condition carrying on merrily under that current level is high.
A blocking diode would stop this, but I wouldn't use one because of power loss ( .7V x whatever current in each string ( say 8A) , about 5Watts/string).
So put fuses in, but can I suggest this as well.
This would cost no power during normal operation, use lightweight wiring, and indicate if you had a problem and where it was.
It uses two pin bidirectional two colour LED's, during normal operation they would be off. In a circulating current condition the combination of LED colors would indicate in which string the issue is. The resistors would be sensible values found by initially adjusting a pot.
 

 
 
 
 

Ok guys
the spare panel and test was just my way of explaining  how I got the idea
 sorry I didn't make myself clear, my bad
my big picture or question  is
would it be possible to use this idea on a bigger scale like connecting to a house that has a larger solar set up  ?
first of all  could it work ? and if so, what  do we need to do it  so on and so forth
so my theory is  that when the batteries are full or the load is small  then all excess energy goes to heating (geyser) and is not being wasted
like having an inline dump load
my thoughts go along the lines of having  a geyser pre feeding your regular geyser  which has say a 4 kw element  ( 220 v x 18a or 100v x 40 a )  ,  and gets heated by the pv   panels 
I've seen a couple of posts about heating water with the excess power which is where I'm going but just from a different approach or thinking out of the box
im wondering if this way could be easier than monitoring the batteries voltage  and special contactors  and all those things
 
ps I did like the idea of placing the element in parallel and not series  nice
pss  the hair thing was  just a pun as I  have very little left , also used it just to emphasize how hare brained the idea  actually is ,  glad to see someone is awake
psss what do you call 10 rabbits walking backwards     a receding hare line
 
cheers
max

Many of them cannot handle it. They use a FET that is PWM pulsed (very similar to a MPPT, except no inductor and no fly-back diode), and hence it has the same open circuit voltage limit.
You need to impedance-match the load with the PV panel. If you want it to work, then 6A must flow at 37V, so the element you use must have a resistance around 6Ω.
If it doesn't, then you need to buck or boost the voltage to match it, and then you have an MPPT for all practical purposes.
But...
Excuse me while I play Grammar nazi for a bit :-)
It's a hare-brained idea, as in a species of rabbit. I'd let that one slide, but you also bear with someone (as in carrying something), not bare (as in getting naked). Please forgive me for that :-)

Our local electric shop sell screwtipe 650 , 1000 - 3000 watt . I have a 650 watt spare . The flange tipe is available with a 1000 watt . They are standard with GAP 50 Lt geysers .

I use similar DC buck boosters and they're generally very stable, as long as the input is higher than the output. 

Hi guys and girls
 I found an interesting online local shop which seems to have a variety of Electronic Modules Boards which could be used for charging and controlling ideas
also dc low power geyser elements
arduino
 led and other things
http://www.elexco.co.za/index.php?route=product/category&path=60
never tried it but thinking  about it  so don't blame me if they no good
cheers
max
 

maybe placing it in the off position with a timer that charges it for some time once or twice a week or month or something along those lines
cheers

Here are some pictures of the finished install.
The BMV702 sits inside the house. Rest of the equipment is in the garage.
I am happy with the install, though I had to neaten up cabling afterwards. I do wish they used better quality circuit breakers.
I am also extremely impressed with these Solar Frontier panels. They are producing for 12 hours in winter. Peak power has been 2.1KW on a 2.04KW array so they peak at over 100% their rated capacity. I have had days with over 11KW production which is 5.4KWh/KW in Winter. I was told to expect under 4KWh/KW in Winter. I can't wait for summer.
 
We have had some net export days where house consumption has been 10KWh and we have generated 10.5-11KWh. I think they system is the perfect size.
 
 
 
 
 

If I remember correctly it will error if it detects the water temp does not rise by a certain predefined degree and time

Don't know about the ones from the china mall, but the one I got from eBay is very good (pics attached of off and on).
 

Slightly simpler... 1.16Wh per liter per degree centigrade. You can derive it from basics if you want to, but I find this is a little easier to remember.
So lifting 300 liters of water by 20 degrees: 300 * 20 * 1.16 ~= 7kwh.

I believe the Kill-a-watt and the Efergy I linked does take into account power factor. The Efergy I have even measures and displays the power factor. In my experience, the plug-in meters do take it into account while the CT-clamp type does not.

Hi Maurizio, would you mind explaining how energizing the timer for 1 min/day will increase the sacrificial anodes life span?

Perfect

The Finder relay's coil and its AC load side are isolated from each other and not related at all. The Finder's coil is the load seen by the BMV's relay and the Finder's coil is a 230V coil and the 230V is switched by the BMV's relay, which is more than what is recommended by Victron.
The geyser's element is a pure resistive load, so if the relay contact is rated for 15A @ 240VAC, and the geyser element draws 15A @ 240V AC, the relay should be able to switch the load for a few hundred thousand cycles as per the datasheet without any problem.
The problem comes in where you are using a relay rated at 60V to switch a 230V relay coil and to make it even worse, a relay coil which is an inductive load.

just a quick 2c worth
what about a dc motor running hydraulic pump and hydraulic motor running the gearbox
by controlling the speed of dc motor you control the speed of the tractor
or
by simple hydraulic valve you control the speed of the tractor
 
cheers
 

I used around 10kwh to get through the night last night, no special treatment, so 16kwh really should be enough.
I don't want to chase up any ghosts (Afrikaans expression: spoke opjaag), but when I hear things like this (large battery that's not lasting the night) I start to think it might not be charged properly (Axpert bug going to float too soon?) or those parallel strings are causing trouble, or something. And usually by the time people ask for help the bank has already sustained damage. I hope for your sake this is not the case.

Hi there
I will try to simplify your system
are you on 3 phase or is there another reason for the 3 inverters?
at a quick glance I think  your system is great
if anyone thinks I'm wrong then please  tell me
my bottom line is this (dumbed down version)
you have 16 batteries  in the picture
therefore each bat has about 2 kw( 200a  x 12 v  = 2400w ) of power but since its recommended not to take the bats below 50% discharge ,  well now you have 16 kw of normal use
my house usually runs a base load of 800w  so with your bats I would last   about 20   hours ( 16000w / 800w)
your solar starts dropping off at 5 ish in summer and starts making reasonable power at 9 ish in the morning( btw what panels do you have)
that equates to 16 hours on batteries
im on single phase (1 inverter)  and only things not connected is geyser kettle and stove (yes I have a pool which runs from 9 30 till 4 ) also I run Eskom at night
if I had your panels I think I could throw in the kettle and geyser
and I think you are right to want to monitor you system
my 2 recommendations are
 check your battery cables connections as mentioned  in the above posts and
 buy cheap  led or digital voltmeters and place one on each battery to monitor your batteries at a glance   ( im sure some one else on the forum will also mention  battery balancers which I don't have)
like I said if anyone thinks Im wrong please  shout
cheers
max
 
 
 
 
 

Hi there
I will try to simplify your system
are you on 3 phase or is there another reason for the 3 inverters?
at a quick glance I think  your system is great
if anyone thinks I'm wrong then please  tell me
my bottom line is this (dumbed down version)
you have 16 batteries  in the picture
therefore each bat has about 2 kw( 200a  x 12 v  = 2400w ) of power but since its recommended not to take the bats below 50% discharge ,  well now you have 16 kw of normal use
my house usually runs a base load of 800w  so with your bats I would last   about 20   hours ( 16000w / 800w)
your solar starts dropping off at 5 ish in summer and starts making reasonable power at 9 ish in the morning( btw what panels do you have)
that equates to 16 hours on batteries
im on single phase (1 inverter)  and only things not connected is geyser kettle and stove (yes I have a pool which runs from 9 30 till 4 ) also I run Eskom at night
if I had your panels I think I could throw in the kettle and geyser
and I think you are right to want to monitor you system
my 2 recommendations are
 check your battery cables connections as mentioned  in the above posts and
 buy cheap  led or digital voltmeters and place one on each battery to monitor your batteries at a glance   ( im sure some one else on the forum will also mention  battery balancers which I don't have)
like I said if anyone thinks Im wrong please  shout
cheers
max
 
 
 
 
 

When I first installed my first solar panels I saw that I needed Type 2 surge arrestors for lightning protection.
My series pv array would have to be less than 145vdc open circuit for the inverters I was using.
I started looking and asking for dc surge arrestors. I did find them but they were very expensive compared to the ac ones.
I did a little more investigation and this is what I conlude from my research.
 
You can use a standard type 2 surge arrestor that you would use in your home  DB board 230vac and it will be good to protect dc even at a higher value  typicaly up to about 300vdc.
This is because ac is measured in rms value and is .707 of the peak value which makes the dc value higher.
The surge arrestor protection component is a metal oxided varistor.
Type 2 surge arrestors can be used for ac or dc.
I had some 230vac surge arrestors spare and used them in my installation.
 
 Later I decided to change my inverters to grid tie.
When I changed my inverters I had to change my pv array to have more panels in series.
The inverters would allow 580vdc open circuit. My pv array would be 450vdc open circuit max. but I wanted  the protection to be higher for me to add more pv panels later.
The surge arrestors I had  would no longer be suitable for the installation.
I started my search again for suitable surge arrestors. 
Larger value surge arrestors were expensive but I did find one place that was very reasonable.
I evaluated the costs and this is what I came up with. The drawing is below.
You can use your standard 230vac surge arrestors in series and for a sigle series pv array you would need 3 surge arrestors to protect a pv array up to about 600vdc.
I hope this will help anyone looking for suitable surge arrestors for protection.
Simple any easy to install.
 
 
 

Have you considered that the fault might be with the multi-meter that you are using and not with the inverters? It is very unusual for 3 systems to have the identical fault.