superdiy

Under ideal conditions you will get close to that, that is if the sun hits the panels at 90

Yes, they suggest that the minimum is 200Ah, because if you are thinking about it, if you draw full load from the inverter @ 4000W and 48V you draw 83 amps from the battery bank (losses ignored) - how long would a smallish battery bank be able to sustain that? The 5KVA Axpert can charge the batteries at 60A via solar and 60A via utility and combine the two to 120A - it is recommended to charge the batteries at C10, thus you can effectively add a 1200Ah battery bank and still charge it without a problem. You may even add a bigger bank, but you'll have to manage it and ensure that you can keep the bank charged or not partially charge it and use it on a regular basis - here I'm not referring to the odd rainy day, but rather to daily cycling.

Yes, those are the zener diodes, but I've modified the circuit a bit since those are 8V batteries and I only had 6.8V zeners. I have 7 x 2A schottky diodes in each "balancer" as well. I played around on the workbench and fiddled the circuit until it gave what I needed. Those batteries were at 9.7 V each at the time the photo was taken and that is why the LEDs are dimly lit. I still have to make my own balancers for my 16 batteries.

What if you bridge the two string inputs, maybe not directly but through two schottky diodes to fool the inverter?

Yes.

Welcome to the forum. I quickly scanned through the manual and could not find anything that indicates that you HAVE TO connect to strings of panels. They do however mention that the 2 strings must be identical in configuration, which makes sense since the unit has only 1 MPPT and not 2. I can understand that they maybe designed something which might work well with two similar strings, but in real life situations anything could happen to either one of the strings (e.g. partial shading etc.) which would put them out of balance and in such a case the inverter should still be able to perform. Have you tested the inverter with 1 string only?

Yes, there is another lamp on the Main DB as well.

The way they "clip" into the adapter plate is a bit iffy and they do sometimes "fall out".

I would prefer having the breaker first and then the E/L, but it should not really make any difference. Inverter OUT - breaker - E/L

I'm not sure about din rail, but quite possibly. You do get Heinemann adaptor plates which you use with the CBI MCBs (13mm breakers). You can actually see them in the top rail next to the CBI MCBs and it looks like one is installed next to the E/L unit as well.

The one with the test button is a 3 phase E/L unit.

I agree. PS If you follow the images in this thread you will notice that the "inverter db" was only added later on - initially the inverter was simply "wired into the main db", but the better choice would be to move all the "inverter circuits" to the "inverter db".

Yes, like that.

Yep.

I've never complained about cloudy days in the past, but since I've installed PV panels I don't like them - the sun must either be shining or it must rain (because we need the rain), but these cloudy days... I don't like them.

This is a sub DB in the garage, 20m from the Main DB, the "Main switch" is a SP+N isolator on the incoming line from the Main DB. The "Plugs" circuit is connected after the isolator and services a plug socket (on utility power) close by. The "UPS OUT" breaker is the breaker on the output of the inverter just before the "UPS/Inverter E/L". From the "UPS/Inverter E/L" it goes back to the Main DB into another SP+N (isolator) on the Main DB. From that SP+N the new neutral bus-bar, CBs and panel lamp (on the Main DB) are fed.

No, like this.

Axpert MKS 3KVA 24V & 3 x Trojan T875's. Sorry for the terrible photo quality.

The Indicator / panel lamp is still not "wired" correctly. It will not be connected "in series" with the live from the changeover switch to the set of red CBs, but rather connected to the live and neutral coming from the changeover switch. Will the "Inverter DB" be close to/next to the current DB?

Yes, that is pretty much it. I've added the one I've been working on in the mean time...

That is unless the inverter is not going to be installed close (1-2 meters) to the DB. If the inverter is going to be installed further away you will have to install more breakers, at least one SP+N on each side. And something I forgot, you have to have another earth leakage unit on the inverter output between the inverter and the bypass switch. And an indicator to indicate that there is power in the DB when the inverter is running, but utility power is off - safety requirement.

Almost, but the inverter input will not go through the bypass switch. The inverter input neutral will be connected to the current neutral bus-bar and the breaker in the live line to the inverter input will be mounted in the DB and fed from the current red 3-phase line.

Yes, your diagram makes sense. Just change the changeover / bypass switch wiring. It will be similar to the top section in this diagram: http://3.bp.blogspot.com/-wS0Fw0Vqoog/UiQzXb403BI/AAAAAAAAFGQ/d5flEUPIxjs/s1600/inverter+to+AC+mains+changeover+circuit.png The DPDT Relay would be your switch, just with another off / dummy position on the switch in-between the "AC OUT" connection from the inverter and "To Mains AC" connection. "To Appliances" in the diagram would be the live feeding the breakers and the neutral feeding the new neutral bus-bar.

The OP does not mention which PWM charge controller he uses, thus we don't know what can be connected to it i.t.o. maximum voltage & current, but the 50A charge controller should be able to handle more panels if the OP has mounting space for them. If you do a rough calculation you will get 300Wp / 24V => 12.5A from the panel and charge controller at ideal light conditions. A 102Ah battery needs to be charged at about 10A (for 10 hours), that is 10A per 24V string. In this case the total current of 12.5A is divided between the 2 strings which leaves each string (battery) with 6.25A. Therefor it will take 102/6.25 => 16.3 hours to fully charge the 4 x 102Ah batteries, but remember, these calculations are for a perfect solution without any losses etc.etc. On a typical 5.5 hour (available sun) day, these batteries will not nearly be fully charged after a single day and by adding 2 more batteries the matter just gets worse. The best option here would be to increase the number of panels or to charge the batteries by means of utility- or generator power.

Hi douwgza You have a 100A breaker on the input of the inverter - that should be 50A maximum. (page 7 in the manual) You have a 60A breaker on the output of the inverter - that should be 25A maximum. (5KVA / 250 V => 20A output) The bypass / changeover switch should be something which can switch both Neutral and Live with preferably an off position as well. You will connect it in a similar way as with a generator installation where the one side is fed from the utility and the other side from the inverter output - you then route either the utility power or inverter power to the load.