Sean White, South Africa

Have you done any checking of your grounding system to see if there is a problem. Could you have a ground to neutral connection in your wiring? Continuity Checks? I am not familiar with the code requirements with your area. Are you required to separate the neutral and grounding conductor?

Thank you for your response.

Here is a breakdown on the layout. The power comes into the invertor from the grid. The main neutral on the grid side is bonded to an earth spike. this earth and neutral are then seperated at the db board. The solar panels are also feeding the invertor. The invertor then feeds power from the grid and the panels if necessary. If the panels are feeding enough power the grid power is shut off automatically. When the panels no longer supply enough power the grid kicks in again. The power fed from the invertor to the db is fed to a main switch switching live and neutral. It then passes thru an earth leakage to feed the plug circuits. There are no neutrals shared with the panel once it has passed thru the main switch in the db board. I have used a megger to check all circuits running from the db board and they are all clear. No Conductors or neutrals are down to earth after the main switch. The panels are earthed to the main earth.

could it be the solar panels interfering on the neutral side.

i assume the neutral goes back to db then onto consumer unit where it is attached to the earth so when the panels is on the resistance between the pos and neg or neutral is low the earth leakage might be seeing this as live to earth if you get my meaning

poss fitting a blocking diode on the neg/neutral from the panel might help

or the inverter if there is an inverter this may be the cause

The diode won't help with AC. The solar panel output is typically fed to an inverter before the power goes to the distribution panel.

I assume what you call an "earth leakage" is the same thing as a ground fault interrupter (GFI) in the United States. These work by comparing the current in one supply conductor with the current in the other. If they are different, it is assumed there is a ground fault (earth leakage current).

If the GFI is monitoring only grid (or only PV panel inverter) current on one conductor, but the other conductor can carry current from both, it should trip every time current is coming from both. In the US, this would most commonly happen if a single "neutral" conductor carries the current from both, but the "hot" conductor on the GFI comes only from the grid. The solution is to rearrange the wiring so both conductors come from the same source. Check your electrical code requirements to see where the GFI should be monitoring the current.

This may be obvious, but are the 2 supplies being kept in sync with each other?

If you connect 2 alternating (AC) sources (i.e. the grid power, and the output from the inverter), then they must be in phase with each other. Is this what your "Control Panel" is doing? If not then you will definately have problems when both sources are connected together.

If this is not possible / too expensive, then the only way around this is, you MUST disconnect one supply BEFORE you connect the other. I realise this means an interruption to the supply to the house, but you either have to keep the two alternating supplies in phase with each other or have a disconnect period between the changeover.

Otherwise I agree with previous posts that the Ground Fault / Earth Leakage unit must see the same current on both Neutral and Active feeds.

Tony

Hmmmm, that makes sense, thanks for the clarification. I was going to suggest an appliance with faulty wiring, but that should trip when either supply is on.

Can you ask Inverter supplier for advice?

Does it trip when nothing is plugged in? Is there anything that only operates when both supplys are on?

My other question would be - Does it trip the Eth leakage unit when only on Solar? or only when BOTH Supplies are on?

You've got me puzzled, but I'll give it some more thought.

Some local assistance may be called for. We may have overlooked something simple, that isnt obvious without actually seeing the installation.

Tony

P.S. Where in SA are you located? We travelled there last December - had a great time!

"I was going to suggest an appliance with faulty wiring, but that should trip when either supply is on." Maybe not. If in one condition the panel voltage is higher than under other conditions, and there is something with marginal insulation connected, the insulation could permit significant leakage current at the higher voltage - most probably through an arc fault to an earthed structure. It's rare, but I've seen it happen with poorly made goods. I suppose such a situation should have been detected with the megger test.

Another possibility is that a switchover transient is causing a nuisance trip. This would likely be an inverter fault, especially if the inverter is supposed to synchronize the panel power output with the grid.

We are located in cape town. More specifically, noordhoek in cape town.

During the course of the week i spent an entire afternoon at the house. I used my megger to check all circuits running off the earth leakage and all came up clear. During the time we were there i switched various appliances on and off to increase and decrease the load which in turn brings the grid power in or out depending on how much power is needed. as murphys law would have it, it never tripped once while we were there. The client maintains that it trips up to 8 times a day. The supplier/installer of the invertor insists it is a fault on our side. I have however been thinking what effect the earth on the panels being common to the db earth is having on the system. Another possibilty is that one of the appliances is causing the tripping, except that when running on grid power it never trips. Not sure any more.

Is your AC ground independent of the DC ground? Or are they coupled? Is the AC to DC charger part of the inverter or a independent unit?

my ground on the panels is common to the main earth on the db. I have been thinking that this may be the cause.