Fritz

@superdiy show off!  grappie net , ,, ek net jaloers. 
 
my DIY cheapy.     10mm threaded rods wat n 50mm x 50mm angle iron regop vas hou. Die panele is voor saam vas met n aluminuim angle. en aan die kante.
So wanneer die wind waai dan stress ek n bietjie.. 
 
 

@plonksterOK, so this demonstrates how much, much better your equipment handles this scenario than the Axperts. In the same scenario with the Axperts, the PV array input doesn't just dip by 150-200 Watts a couple of times - it plumits to zero, holds it there for 7 seconds and then takes another 30 seconds to gradually restore from zero to the full input of the PV array. This is a heavy toll on the battery bank, especailly if you are running a 5Kw load with 4 Kw PV array input. This can happen on a daily basis if, say, the washing machine and oven go on at the same time. It also means that when your input is really good and the whole system should only put a 20 amp strain on the batteries for a while, you have a sudden 100 amp strain (48V system) on the batteries lasting for almost a minute and returning to a 20 amp drain. For many systems the battery bank simply won't cope with this kind of load and even for battery banks that can, it's likely to shorten their overall life. 
This is something I did not know about the Axperts and is an eye opener. Of course these are only features that you can find out about through use and will not appear in the specs.

hi, 
 
 
SOLD
 

I use a simple relay that is closed by high battery bank voltage and with the fact that the Karoo is sunny most days it works well. Tried to keep it simple. Geyser element changed to 1500W which is more in tune with the excess generated by my PV array.
http://www.ebay.com/itm/Multi-function-Voltage-control-Relay-Timer-Delay-Switch-Voltage-Protection-12V-/271832274268?hash=item3f4a77555c:g:PsQAAOSwbYZXcIJf
 

Okay, I see it. While the fuse is intact, the base of the PNP transistor is pulled up to the positive line (well, within about 0.7V of it). This is technically enough to turn a transistor on, but because the LED is on the emitter side that raises the emitter voltage by about the same amount so the transistor is off. When the fuse goes, R2 pulls the base down to ground and Q1 turns on. R1 limits the current into the LED.
For a 48V bank I'd use 6k8 for R1. I can't see in the picture what you used, though it looks like you used 27k for R2 (which is perfectly okay).
The idea I had in mind is closer to what @superdiy posted above. Just stick an LED across it. While the fuse is intact the voltage drop over the fuse isn't enough to bias the diodes (or the LED) forward, when the fuse goes... lighty lighty...
Edit: D1 is there to prevent the base of the transistor from being pulled down to ground via the load. I think. Because if that happens then the transistor goes boom.
Once again, Afrikaans is so beautiful in this regard. We don't bias a Transistor. Ons span hom voor.

My solution was a twin port plate also for Kwikot geyser  and 2x 1500W elements which are reasonably easy to source.
 
Addition: When the photo was taken I had a 1kW and a 1.5kW elements now we have two 1.5kW elements.

Good day, 
I recently finished my solar project installation at home. 
I thought it might be a good idea to phone my insurance just to notify them about my upgrade. I dont want to take a risk with highveld thunder storms approaching. 
The consultant sed its good , just send the COC through.  .... mmmm eish... what COC??.... hehhe
1. Do you guys all have COC's?
2. Did you notify your insurance?
3. Who does COC?
4. How much?
 

@superdiy show off!  grappie net , ,, ek net jaloers. 
 
my DIY cheapy.     10mm threaded rods wat n 50mm x 50mm angle iron regop vas hou. Die panele is voor saam vas met n aluminuim angle. en aan die kante.
So wanneer die wind waai dan stress ek n bietjie.. 
 
 

HI DB9 
I like the idea of having built in redundancy.  Make perfect sense to separate a second array on a separate MPPT. According to the 10-30A Microcare manual the Microcare MPPT cannot be paralleled with another PV array. This is immediately not good news.
Fritz - You might as well get a second Axpert and cover your bases. If you are worried about the high quiescent draw you can switch one inverter off and its SCC will continue to operate and charge your batteries.

yeah i would also like to know this. 
My axpert got its own built in MPPT (60A) and then i buy a stand alone MPPT with its own PV input but both the CC outputs are connected to same battery bank.. 
Thus you can increase your input PV power in theory. 

Your higher usage during the night is probably because of the fact that previously the inverter used battery power to supply the load say until 11:00 and then it went to bypass and used grid power for the remainder of the night.  Now your battery bank changed and you said that all the settings were changed a few times and now the batteries might supply the load maybe only until 19:00 or 20:00 or not even at all and thus you are using grid power for a longer period during nighttime.
You'll have to get the software going to monitor all of this carefully and then you can make a few changes.
I will also start by changing setting 31 to SbE (enable) to enable the inverter to use PV power to supply the load as well as to charge the batteries.

@Marie1, If i were you, I will still buy the Battery monitor even if you decide to go for monitoring software. A battery monitor will show you the true State of Charge of the battery bank. With running a heatpump late afternoon, I can almost say for certain that the 9 panels wont keep up with the heatpump and all the other load and you might actually start to deplete your bank even before the sun sets. Although the sun is still shining, the PV production will decrease significantly in the late afternoon. A combination of the BMV and software will be the best option in my opinion. 
EDIT: While I was typing, i saw @Fritz saying almost the same about the load.

you are using heavy loads late in the day. the SOC might be lower than you think. 
I do my heavy loads (geyser, pool) 10am -2pm
 

Heating your geyser with PV's makes room for a more flexible/adaptable/multi-functional/upgrade-able.. etc etc ....  solar system in my view. 

Hi DB9
It is no contest. A solar geyser will heat water more efficiently than PV.
I will use my situation as an example. We have gas geysers. I use excess energy to heat a standard electrical geyser which preheats the water. On most the water does not need further heating. If however I decide to use that energy in the workshop I can. Why do I have excess energy? I need to cater for some days where we do the washing and ironing and generally use a lot of power. Will I spend my next 3k on a geyser? Probably not. Another R8k  would give me 750W of panels and give me maximum power for a larger part of the day. A friend who owns a game farm has about 50 evacuated tubes in his shed from solar geysers that he has had to abandon. I would consider a retrofit system using his tubes but I am loathed to spend money on a system that can only heat water.
A heat pump is even more attractive but most seem to have a start spike and since I use a relay to switch the geyser on/off a resistive load makes sense. The R3k solar geysers I have seen might give you a hot shower but definitely not a hot bath and if you need to have a glycol system the expensive is even greater.

Heating your geyser with PV's makes room for a more flexible/adaptable/multi-functional/upgrade-able.. etc etc ....  solar system in my view. 

Heating your geyser with PV's makes room for a more flexible/adaptable/multi-functional/upgrade-able.. etc etc ....  solar system in my view. 

Heating your geyser with PV's makes room for a more flexible/adaptable/multi-functional/upgrade-able.. etc etc ....  solar system in my view. 

Which is probably reason number 1 why I changed all the lights to LED.
Now I yell at the kids about the fridge... because they open the door, and then it hangs open while they decide...

DB, there is no way that my solar geyser installation of R17k can repay itself "in a matter of months". It saves R300 power per month so payback is more like 5 years. I didn't pay that amount myself, I was replacing a burst geyser in any case which the insurance covered and I claimed the rebate which was still available from Eskom at the time. But I wouldn't pay that outright to replace the the other geyser.
But again, for this discussion it is irrelevant. I have all the equipment already and it was bought for a different reason/motivation/excuse. I don't calculate the payback on my solar installation, it is not why I installed it. Yes, it saves me money and I try to get as much savings out of it as possible but it's sunken cost. I like the concept of solar and renewable energy, I like playing with the equipment, etc. So I have more personal payback than just the energy saving, it's also entertainment. It's sad, I know.

I think the advantage with the SolarImmersion and PV is that once the geyser is at temperature, you can use the rest of the power generated to save on your power bill. Something you cant do with a solar geyser. Also, if you already have a solar system (PV), the SI is significantly cheaper than a solar geyser.
One of the issues with a typical grid-tied solar PV Installation is that you can have a lot of unused solar power. The SolarImmersion is supposed to increase self consumption.

My Solar Immersion geyser controller arrived a while back and I had it installed last Monday. Unfortunately we've been having some $#%^ solar power weather on the West Coast recently so today was the first day I could get a clear uncluttered graph to show how it works.
This is how my system is confibured. I've got 3kW panels connected to an Infini 3kW+ unit, the inverter has a connection from the DB and all loads in the house except for the two geysers and the oven is connected on the output of the inverter. I also have a 500Ah battery bank that I discharge by 15% every night. If excess energy is available the inverter is setup to export that, which in essence then goes to the DB. If there is no other consumers (geysers or oven) on at that time it will be exported to the municipality who will get it for free as my meter does not turn backards.
The Solar Immersion unit is installed between the DB and the geysers. It can drive two geysers, sequentially, not simultaneous, I currently have it wired only to one geyser as the other is already a solar geyser. A CT clamp is installed around the incomer (connection to municipality) through which the unit senses when you start exporting. As soon as it sees export it starts to send some power to the geyser through what they call frequency modulation. I have no idea how it works. When the geyser reaches temperature the unit can then switch to the second geyser, in my case it just stops sending power.
Below is a graph of my household power today. What you will see is:
Red line is load to the house consumers, output from inverter.
Orange line is the connection between the inverter and the DB, if it goes negative the inverter is sending power back to the DB.
The blue line is the municipal supply, if it goes negative I'm sending power to the grid.
Solar starts at around 07:00, grid and inverter lines split from load which remains constant.
At 07:30 inverter and grid reach zero and the inverter starts charging the battery bank.
Battery charging continues to ramp up as solar power increases until it reaches the maximum of 1.5kW at around 10:00, then the inverter starts exporting execess energy to the DB but the blue line (grid connection) remains zero as the Solar Immersion unit starts pushing power to the geyser. Actually the measurement shows it running negative (export) by a small amount, about 50W.
This continues until around 15:15 today when the geyser reached temperature and the thermostat switched it off, then the export from the inverter goes directly to the grid as there is no other consumers on the DB that can absorb it.
So in general the area between the blue and the orange line is the amount of power soaked up by the Solar Immersion unit.

For now the system works quite well, it soaks up any excess available so I no longer donate power to the municipality. It is not a grid limiter, if the geysers cannot absorb energy the inverter will export to grid. I can now consider adding an additional 1.5kW panels as I do not have enough panels to drive another geyser and will help to cover usage better in case of cloudy weather.
Just thought I'd give a short report is someone else might find it useful.
Cobus

Yes, exactly. Think of it as pushing against a higher pressure (higher voltage). That higher pressure (voltage) can do more work per time )power) with the same flow (with the same current). So you need more power now (charging a battery with rising voltage) so that the battery can provide more power later (58 V at 100 A is more power than 48 V at 100 A).
Conservation of energy.

Fritz: re 7 strings. No, remember that the 60 A limit is at the output of the MPPT. With say 90 V at the panels and say 53 V at the battery, you have 90/53=1.7x less current at the input of the MPPT. So that's a limit of some 60/1.7=35.3 A, say 36 A with losses. So to max out the MPPT when the battery is at 53 V you need 90 x 36 = 3240 W of panels. Working with panel current, that's 36/8.5=4.2 strings. That's about1.7x less than the 7.1 you came up with.
But that's at maximum panel output, which you rarely see. It's better to have more panel power available, so you get more use of the MPPT in cloudy conditions, at the expense of some clipping on sunny days around noon. So 7 strings is probably a reasonable number, just for the wrong reasons ☺
Edit: actually, 1.7x (as pointed out in an earlier post, it varies with battery voltage) is a bit high for an "overclocking factor". 1.3x is more reasonable, so 5 or 6 strings (4.2x1.3=5.5).
Edit 2: ising Solamahn's factor of 1.4x, that would tip it towards 6 strings.

^^^ That one. But lets get rid of the power figures and talk current.
It makes no sense to talk in terms of power because the limits on the MPPT is not in power but in ampere, so the amount of power depends on the voltage that you are working at.
If the controller can do max 60A and your batteries are at 48V, then it can do 2880W. If the batteries are at 57.6V (Absorb) it can do 3450W.
The same goes for the inverter side. At the lower voltage it needs 83 amps to make 4000W. At the higher voltage it takes 70 amps to make the same power. So on the lower voltage, 23A will come from the battery, and at the higher voltage, 10 amps will come from the battery.
The difference will always come from the battery because in the Axpert, the MPPT is connected directly to the DC bus, the DC bus is connected to the battery, and the inverter is connected to that same DC bus. It's all interconnected. It is no different to what us non-Axpert people do with our external charge controllers. We just have extra cables around :-)