Chris Hobson

Hi All After a period of absence I am back without my much loved dual Axpert install. I now lived in (clears his throat) Gqeberha (Port Elizabeth for those of you without a throat infection). My new home has a 3 phase supply and a massive 30 kVA 3P generator for the regular power outages. Heaven help us once loadshedding starts. The roof is slate and probably singularly unsuitable for a PV install. Not to be defeated I do see there is space for a double carport which will then accommodate PV on the roof. At this stage I am looking at a Solis 3P GTI. Anyone have a system that they find superb? Chris

cheap and simple.... CT Ammeter.

I just want to check you have a combiner box for your 5S/2P array.

OK CB on PV to MPPT and depending on load CB/battery disconnect between battery and load I have seen a 125A DC CB but they are not common.

Use the direction of current flow into the switch i.e. the source side (PV in this case). You understand why you cannot use a DC CB between MPPT and batteries as sometimes the MPPT is the source and sometimes the batteries are the source. If you have a separate set of wires directly from the battery to load then you can have a CB between MPPT and batteries but then you need a CB/battery disconnect on the load cables depending on the maximum possible draw. I think you have a Victron MPPT. Some Victron MPPTs have terminals for load and others do not. I would be inclined to have a DC CB between PV and MPPT and a battery disconnect between batteries and load. A second DC CB would be superfluous between MPPT and batteries. Just make sure your cables are specced properly.

Morning you need to be careful wiring up DC breakers so that the magnetic field directs the DC spark into the catch cage. If the source is your PV you can bring the wire into the CB either at the top or at the bottom like an isolator but then you must be consistent and ignore the + and - on the other side. Your current flow between MPPT and battery is usually bi-directional and DC circuit breakers are not designed for bi-directional use. The Amps you are going to draw from your battery is could exceed what a DC breaker is able to switch. So I would recommend you have a DC breaker between PV and MPPT and a battery disconnect between battery and MPPT. You don't mention what size you PV array is and whether the array is made up of several strings or the size of your inverter. So my recommendation is made with incomplete facts. https://www.youtube.com/watch?v=Cup5fMGaE2g

The fan speed is definitely related to the SCC. We are having a day with broken cloud and the fan speed is varying all the time. Since I have the model with external SCC heatsink the increased fan speed seems unnecessary although I would admit the heatsinks are considerably cooler.

I am going to have to go back to 72.70c. The noise levels are too distracting and although the ability to go into standby is really convenient the noise trumps it. I don't think the fact that the machines run 8 degrees cooler can be used to argue in favour of the more responsive fans. Reversing the fans in 2016 has already got the machines running 15 degrees cooler.

Morning Gerrie - the inverter not switching back on is due to the battery voltage being too close to the battery low cutoff voltage. What the difference needs to be depends on what firmware you have. With @Coulomb's lithium firmware I think it is 2V and vanilla it's 4V. It may be 1V and 2V respectively I can never remember. You can solve this by temporarily lowering the setting of Program 29, switching on the inverter and raising the setting back to its recommended value. There are scenarios where the battery voltage is low and if the inverter was on it would run but the voltage is too low and the firmware prevents the inverter from switching on.

I noticed yesterday that the SCC heatsinks were considerably cooler and that the inverters became quiet when we were in float even though I was still drawing 2kW. I have 3000W of PV on the one inverter and 1500W on the other.

My inverters are in our family room/TV room/office next to my desk. The inverters have never bothered me before - when someone used the microwave the fans would be noticeable but other that that the PC made more noise than the inverters. Now with the 2kW baseload I have during the day the inverters are 8 degrees cooler but irritatingly noisy.

A DC contactor where the coil is closed via AC would be ideal NO would power off grid NC would power grid tie. ABB make a DC compliant contactor or you could use a ordinary contactor with a snuffing capacitor.