Bush Man

Thanks, Coulomb, much appreciated!

Dear All The current setup is as follows: Completely off grid, in the bush, no Eskom, no Wifi. 12x250 Watt panels, 4 strings of 3 each Microcare 4 string combiner unit 2016 Model Axpert/Mecer SOL-I-AX-5M 4kw 5kva Inverter 8 Omnipower 180 AGM batteries (actual rating 150Ah), 2 strings of 4. Very light on power, fridge and LED lights only, with the occasional microwave or a hair dryer use for short duration. Calculated night time consumption with fat built in is 3kwh. The place is used as a weekend place by different people, so there is no one there to monitor and keep an eye on the system. The batteries have served well for 5 years, but it is time to look at replacement. After much reading on the forum and elsewhere, the current choice is for 2 x Pylontech UP5000 4.8kwh batteries, with a combined capacity of 9.6kwh. Now for the one remaining question, specifically relating to the Axpert’s cut-out voltage setting off grid. The Axpert inverter is known for inaccurate SOC readings. It would typically drop the voltage reading by around 2V under load, and then recover. With a 4V range between full (52V) and empty (48V), the system easily temporarily dips below 47V under load. With AGM batteries the solution was simple – set the Axpert cut-out voltage lower to provide for the dip. The Pylontech’s internal BMS will, however cut out the battery when this happens. It can be manually reset, but one doesn’t want unfamiliar people fiddling with the batteries in the dark. The normal go-to for a more accurate SOC reading by the inverter would be Centurion Solar’s ICC Raspberry Pi. However, according to both Centurion Solar and this Pylontech guide this will be of no use in an off grid scenario. I believe it works only for the back-to-grid setting in a grid tied scenario, and not for the cut-out setting in an off grid scenario. In addition, this model inverter will not communicate with the Pylontech BMS through the comms cable available from Pylontech. That leaves the Axpert’s fluctuating voltage reading through the battery cables as the only possible communication between the inverter and the batteries with regard to SOC. The only way to deal with it that I know of would be to set the Axpert’s cutout voltage at, say 47.5V, so that the Axpert cuts out before the batteries do. Switching on the microwave while the batteries are still at, say 49.4V, the inverter voltage reading will drop to below 47.5V and the inverter will cut out. This, however, will mean that a huge part of the available battery capacity (everything below 49.4V in this example) will be lost / unusable. Is there any other way to have more of the batteries’ capacity available with this inverter in an off grid scenario? Regards Bush Man

Afternnon All I am looking for one of these. I have a an existing bank and I need to replace one. Any ideas as to whom I could ask? Zero eight three, six five four - eight two zero one

Thanks, Coulomb It turns out Sun Pays in Cullinan where I bought the newer model without heat sink also stocks the old one with the heat sink. They exchanged it for me. Haven't spent a lot of quality tome with it yet, but fan is definitely running a lot less than the sinkless model, although more than the sink models I installed before. From that I gathered it must be a firmware issue. I'm not very comfortable about computer stuff, so I can't tell you which firmware it is running. If the fan runs too much, I will definitely get back to you. Regards Herbert

I do have a lightning damaged previous model with the heat sink. Any chance of combining the two to get a reliably working inverter with heat sink and without the fans blowing most of the time? I would obviously take it to someone who knows his stuff.

Morning All! The current 4kW 5kVA Axpert comes without the heat sink that was incorporated into the previous model. The result is that the fans work more than half the time. This is very disturbing with the machine in your lounge in a quiet bush place. On the previous model the fans only came on briefly under a big power surge. Any idea where I can still source the previous model? It was generally available until 2017 (I think).

For the record, it did come on by itself after a couple of hours of sun.

Thanks, Plonkster It's an 5kVA Axpert in a remote location and I have guests out there. Wouldn't like them to start fiddling with switches unless necessary. Will give it until lunchtime. Fridge should be OK until then. Low voltage cutout is set at 47V, but after a sunless day yesterday they had two hair dryers going this morning, with predictable results. Sounds as if it is sunny today though.

Morning Guys! Spring and overcast weather is with us again. In my off grid situation, when the Axpert shuts off due to low voltage, will it restart by itself when the batteries have charged again, ot do I have to reset it by switching it off and on again using the power switch at the bottom?

Thanks Guys! Wasn't aware that I could switch off the Axpert as well. Are you saying that even when switched off it still monitors the batteries and keeps them full?

I have an off grid cottage that I use once or twice a month. 12x255W Enersol panels (4 strings x3), 8x260 Omnipower Batteries and a Axpert 5kVA Inverter When I'm not there, should I switch off the AC Mains, or should I leave a fridge or similar running to keep up a little cycling of the batteries? The panels keep on feeding into the inverter&batteries in both scenarios.

Thx! My concern was more that the Axpert cooling fans would start every time the fridge starts up, which would be noisy and add to the Axpert's wear. From my recollection with the first installation though, the Axpert's additional fans only kick in somewhere past 1kW. In addition, the fridge's supposed 800W start-up draw would only be for a second or so, probably in any event too short to trigger the Axpert's additional fans.

Let's say every start-up uses 5 x 160W = 800W, it wouldn't be nice if the 5kva 3kW Axpert has to start its fans every time the fridge comes on. Do you possibly know at what watts the Axpert's additional cooling kicks in?

Thanks! Inverter is a 3kW Axpert, with 8 x 200 (260) Ah Omnipowers and 12 x 250W panels, so start-up current should be fine. I wonder why two similar models would have such a large difference on wattage? Is it possible that the new model has a "turbo" function and only uses the 160W when that is switched on, otherwise only using around 90-100W? Or would the 160W be a fixed figure, with the compressor running for shorter periods than for the 90W model? Will buy, measure and revert for posterity in any event.

Afternoon! Two years ago I installed a Bosch fridge-freezer in an off-grid place which I built - model KGW36XL30S, A++, 90W, 226kWh/year (619Wh/day). It's still running beautifully. I measured consumption over a period of 3 days, and it was spot on at arount 600Wh/day. That model is no longer in stock. For the place that I'm building now (also off grid), I'm looking at the similar Bosch Fridge-freezer KGN46XI32, A++, 160W, 258kWh/year. My concern is the 160W, vs the previous model's 90W, although the annual kWh is similar. Should I be worried about the almost double wattage?