NigelL

AC-DC Dynamics (Paarden Eiland) also sell the threaded copper bars in various sizes - e.g. https://www.acdc.co.za/pages/product-individual?BFC3010 See Rubicon for DC Fuses and Holders - https://www.rubiconsa.com/files/2019/04/Pv-fuses-and-holder.pdf

You may still run into problems if there are single-phase loads that suddenly get a step-change in voltage due to the sudden phase change, as the contactors switch over. It may also be tricky to coordinate the disconnection of 3-phase loads and the switching of the contactor. There will be a lot of smoke and tears if there is even the briefest overlap 😬 A single-phase Inverter must synchronise its output to one of the three incoming mains phases - and should then only supply power to loads that same single phase. This is normally done via a change-over relay that cannot ever allow a cross-connection between the inverter and the incoming mains, even with a relay failure.

Unfortunately this scheme will not work if you have 3-phase loads (e.g. motors). The problem is that each of the incoming phases of the 3-phase mains are 120 Degrees out-of-phase with each other - there is approximately 400V between each phase. To suddenly switch this to single phase, with 0V difference between the phases, will cause havoc with any 3-phase loads!

The City of Cape Town regulations are as follows: Maybe there is a similar exemption in your municipal regulations?

I still think there is a possibility that noise is coupling from the AC Mains to the ADSL line, via the Router Power Supply. A transformer-based power supply should not couple noise into the ADSL line. Alternatively, if you have a small UPS, try using this to power your ADSL Router with AC mains to the UPS unplugged.

An ADSL router will typically loose sync if there is interference on the telephone line - especially if the interference couples slightly differently into the two telephone wires. My guess is that the problem is caused by switching noise, generated on the Axpert AC output, which is being coupled into the ADSL line. Suggestions: Try a different power supply for the ADSL Router (ideally a transformer-based PSU). Try re-routing the ADSL line so that it does not run parallel to any mains cables.

Yes - that makes sense. Maybe the "first" battery, that DeepBass9 mentioned, was the one connected to ground?

Hi Phil, of course you would not get fireworks in your situation - due to your battery being "unearthed". I do understand and agree with your explanation - my post was aimed at DeepBass9. Given the assumption of a ground reference (as stated in my previous post), this is a reasonable explanation for a (very) small electrical difference between batteries, dependent on their position within the string.

Another possible explanation is that the first battery operates at the highest voltage relative to ground (assuming 0V ground reference). This high voltage, relative to the surroundings, creates an increased opportunity for an unwanted low-level conductive path to ground. This could be from accumulated deposits from vapour released during charging etc. One can observe a related effect in electronic circuitry that is installed near the coast - i.e exposed to humidity/salty atmosphere. The corrosion and degradation of electronic parts increases significantly as the operating voltage increases (unless protected with conformal coating).

This voltage is most likely due to the input-filter capacitance of some switching power-supplies connected to the output of the inverter. This also points to a possible mechanism which causes the tripping. RCDs are designed to trip if there is more than a 30mA difference in current between Live and Neutral. There is a fair tolerance on this level, so one can get RCDs that will trip at say 20mA (your electrician should have a meter to measure the trip threshold). When the Neutral-Earth voltage jumps from 0V to 60V, as the grid is disconnected, this could result in an additional small current between Neutral and Earth - which may just push you over the limit for the RCD. The tripping problem could also be a combination of factors - i.e. an overly sensitive RCD, a high residual earth leakage from your appliances (especially "surge-protector" plugs and anything with a heating element) and the problem of the floating Neutral on the output of your Inverter. I recommend contacting someone with experience in wiring the Goodwe Inverter.

I am not familiar with the GoodWe inverters, but this does not look correct. I suspect that you will solve the tripping problem if you can work out why you have a high voltage between Earth and Neutral, when disconnected from the grid.

A high Neutral-Earth voltage, on incoming mains, suggests a fault in the Protective Earth-Neutral (PEN) bond, or some faulty wiring between the incoming mains and the main DB. A high Neutral-Earth voltage, on the Inverter output, points to a wiring problem between the Inverter and the backup circuits or an internal fault with the Earth Relay. What brand Inverter are you using?

I suggest that you verify the following two things: The voltage between the incoming mains Neutral wire and Earth is close to zero. The voltage between inverter output Neutral and Earth is close to zero. Test this with Mains connected and also with Mains disconnected/Loadshedding. If there is any significant Neutral-earth voltage, or change in voltage as the inverter kicks in, this could point to the source of the problem.

Remember that the output current (into the battery) is limited to 70A, so strictly speaking the max charging power (@48V) is 48V x 70A = 3360W. The battery will most likely go above 48V so you do get a bit more than 3.36kW, but 4kW is a bit on the optimistic side. Assuming your batteries are okay with the higher charge current, I would personally opt for the 85A version so that one can take advantage of hazy/cloud-edge conditions where your panels can generate over 120% of their rated power. The MPPT will also then spend less time running at max output - possibly improving long-term reliability.

Hi Andrew I have had the BlueNova BN52V-230-12k (52V 230Ah 12kWh) for just over 1 year and am very happy with it. The guys at BlueNova have also been very helpful with the odd technical question. The main point to note is that the internal BMS is not very accurate at measuring low discharge currents - so you need to include a BMV712 (or similar) to accurately measure current into/out-of the battery so that you have a realistic idea of the SOC. Edit: BlueNova is now part of the Reutech group, so have significant backing, which is useful for a product that has to have long-term support and warrantee.

This only applies if you want to export power back into the grid. You still have the option of staying on the Home User tariff and keeping your existing prepaid meter (non-AMI type) - as long as you choose not to export power to the grid. I have recently had this option approved by CoCT.

It is also worth noting that, even if you get approval to export energy back to the grid, the following rules still apply (for the City of Cape Town): You have to remain a net-consumer of electricity over a rolling period of 12 months (i.e. you cannot export more kWh than you use in one year). If, over a month or so, you export lots of more power than you use, any "credit" will carry over to the next month (but will never be paid back to you, because of point #1). This makes it hard to justify the installation cost of an AMI meter.

Hi Plonkster I see that ElectroMechanica have some options - see http://www.em.co.za/Home/Industrial-Plugs-and-Sockets/#2 Maybe a panel-mounted "inlet" on the back of the cabinet? I'm not familiar with the electrical wiring rules relating to this type of connection..

See my post here https://powerforum.co.za/topic/2111-blue-nova/page/2/?tab=comments#comment-58949 Before I installed the BMV-712 I had no real idea of the real state of charge, so had to frequently check the battery voltage and manually enable the charger (i.e. lots of time and effort). Since installing the BMV, one can rely on the SOC reading, so ESS can work effectively. There is no need to micro-manage anything anymore 🙂

Have you considered fitting a BMV-712 to monitor the state of your batteries? I am not sure how accurately the Pylons measure the battery SOC - I had to add one to my system and would ideally have planned this from the start. I'd rather do the trunking etc. once 😉

You will also need to add a parallel diode (e.g. 1N4007 or similar), connected in reverse to the LED, so that the LED is not exposed to a large reverse voltage when the mains voltage polarity is reversed. Most LEDs will have a maximum reverse voltage rating less than 10V so will degrade quickly without this reverse diode protection.

Yes, a dimmer module will normally consume about 1W when "off".

The dimmer control module is designed to have a small current flowing through it even when "off" - this is used to keep the electronic control circuit powered so that it can react to button presses etc. While this current is too low to power up the 50W downlights, it is sufficient to keep low-power LED bulbs partly illuminated. There are two of solutions: Remove the dimmer module and fit a regular on/off switch. This makes the most sense if you are not fitting dimmable LEDs. Some lighting suppliers stock a "dummy load" that one fits in parallel to the light bulbs. This passes the low-level current that keeps the dimmer switch happy and the LEDs should then operate correctly.

I recommend contacting your supplier - a 5kVA Multiplus 2 should not be thermal-limiting at around 2000W when your ambient temperature is 22C. I have the smaller 3000VA Multi-2, and it has never once had an over-temperature alarm even when running at full power (2400W). The ambient temperature in the house has often been over 27C in summer.

Can you confirm that the internal fan in the Multiplus 2 is turning on when it is supplying a load as shown previously?