superdiy

Not following. You say you have 2x 265W Solaire Direct panels connected in series and want to add another panel in series - that is effectively 1 series string. Then you mention the "bottom side" on all fuses are connected to a bus bar. To me it sounds like the panels are connected in parallel rather that series?

If you have a charger capable of performing and equalize charge, then maybe do it once a year.

Batteries should ideally be charged at rates between C10 and C5. If you have a 100Ah (20h) battery you should charge it at a rate of between 10A (100Ah/10) and 20A (100Ah/5), preferably at a lower current. Just keep in mind that at a lower current it will take longer to fully charge the battery and especially if you are charging it by means of solar, you'll have to make sure that the batteries will be charged fully during the day. According to your batteries' datasheet, they are 122Ah (10h) and you have two strings in parallel, so you effectively have a 244Ah (10h) battery bank, which should be a bit more at 20h, but without getting too technical, lets round that to 250Ah. Your ideal charge rate would thus be between 25A (250Ah/10) and 50A (250Ah/5). Depending on how deeply the batteries are discharged in the morning, you'll have to determine at what rate you'll get them fully charged during the day. I would suggest that you experiment with different charging current settings and monitor the level of charge. Maybe start with a 30A or 40A setting and monitor the batteries' state of charge - if they are fully charged by 11:00 in the morning, then lower the current, but if they are not fully charged by about 15:00, then raise the current etc. etc. The datasheet does not contain a graph indicating cycles @ DoD. It only mentions 10 year design life at 20

I'm using VRLA with AGM tech batteries and the datasheet specifies "Equalization and Cycle Service Charging Voltage", so yes you probably would do it occasionally. Just don't do it with Gel-type batteries, as per above.

For DC: bridge rectifier, resistor and LED. For AC: capacitor, diode and LED - diode reversed and parallel with LED. Depending on the voltages, I can draw up the diagrams and suggest component values. Tell me if you require it for AC or DC and what the maximum voltage across the fuse would be if it blows.

Interesting...

No, infini and cut-off set to 48V.

That is a pity, but practically it is not an option to set cut-off to 42V - that would ruin any battery in no time. At 46V they are already about 85% discharged.

DeepBass Currently, almost a month after the shortest day, my inverter reports on average 2.75KW from my 3KW panels at midday on a sunny day. When I still had only 11 panels installed (2.75KW) I once got over 3KW at midday on a cold day in April. Remember that most of the panels are also rated at -0 +5% output.

Hi Chris It is quite possible to get more than 3KW from your panels, if it is cold and if you are getting almost direct sunlight. My calc to the above would be: P = V x I (91.8V x 36A) = 3304.8 W from panels Power consumed = 2415W Difference: 3305 - 2415 => 890W Battery is charging (not discharging - this might be a cosmetic bug) at 13A => 13A @ 52.1V => 677 W 890W - 677W => 212W in losses? Maybe the 3305W from the panels are not spot on either... Does this make more sense?

Hi Carl, I cannot comment on the "better choice of battery " statement, but when it comes to gel batteries, you have to prevent the generation of bubbles in the gel, because since the bubble generation is not reversible it reduces the capacity of the battery and shortens its life. Bubble generation typically occurs when you charge or discharge the gel batteries at a higher than recommended rate, or "over-charge" them e.g. while equalizing them.

Received the Axpert 3KVA MKS 24V yesterday and I can confirm that it also only has 20A and 30A charging options, nothing less.

Well done Chris!!!

Cool!!! Post some pics.

Hi Carl I don't have an Axpert inverter myself, I've ordered one for my dad, but I'm still waiting for it to arrive. I'll be doing the installation and set-up and only then I think I'll maybe be able to answer your question. A friend of mine do have an Axpert and he is still happy with it. Regards

Thanks alistair.

Best would be to check your specific batteries' datasheet. I noticed in one of the Trojan datasheets that some battery manufacturers suggest doing it once a month, but Trojan recommends doing it once or twice a year at most.

Hi jaco_n The solution with the change over switch/contactor will not work. If you want to be able to supply the load from solar and draw from ESKOM if solar is not sufficient then you'll have to have an inverter capable of combining ESKOM and solar and even more, if you want to feed back to the grid you need an inverter with grid-tie capability as well. Your only solution then would be something like the 10KW 3 phase infini going for about R45000 or maybe another more expensive 3 phase inverter with grid-tie capability. If you however are willing to have your connection converted to single phase, you can look at a single phase inverter, but there you are basically still limited to the 3KW infini which have the grid-tie option and which will also still supply your load when the grid fails (load-shedding). Most grid-tie inverters cannot supply the load when the grid fails - they simply switch off and that is why I say you are pretty much limited to the 3KW infini or may something like the more expensive Imeon inverter. As far as I'm concerned there is no easy (cheap) way out, if you want to keep your existing 3 phase connection and quite high load (40A? per phase).

I don't know exactly how the bridging works and what the configuration options are, but If that is the case, then jaco_n's problems are solved!

Hi Chris That is great news, thanks. I hope the 3KVA can also go that low. I'll report back after I've received and checked mine. Thanks

Hi jaco_n Do you want the system to act like a UPS or are you manually going to transfer between inverter(s) and ESKOM? The reason why I'm asking is that if you are going to switch over manually, you can just as well install a 4 pole changeover switch, which is available off-shelf. If you want an automatic transfer switch you can use a suitable 4PDT contactor and connect its coil to one of the ESKOM phases - as soon as ESKOM fails, the contactor coil will be de-energised and the load will be transferred to the inverter(s). Regarding the solar / battery connections: If you are going for the Axpert inverters you can install the additional cards and cables as per the "bridge" configuration and use 1 inverter per phase. In "bridged" mode the inverters share the battery bank and PV panels. Just keep in mind that the output on the 3 separate inverters will be perfectly in sync as opposed to a normal 3 phase connection where the voltage and current on the 3 phases differ by 120

What I understand from the 70A in the manual (in your case / 4KVA & 5KVA) is that the 70A is the combined charging current - 60A from PV and 10A from Utility, but then again, Utility charging current can be set to 2A (4KVA & 5KVA) as well - then there should have been a 62A option for combined charging as well. I any case, it is not a big issue, I'll just wait for the inverter to arrive and check it out myself and then decide on the battery types and Ah's. Thanks Chris Edit. Re-reading your post now.. You say you have options 10A - 120A for option 2? As I understand the manual the options for the 4KVA & 5KVA's are 70A, 80A, 90A, 100A, 110A and 120A only - is that not the case on the inverter itself? Then the manual is definitely unclear. Guess it would be best to wait until I get the inverter and can confirm it.

Hi Wetkit & Buks This might fix your problems with the readings that are not spot-on: Battery voltage calibration (1 November 2014) from http://www.ostrovni-elektrarny.cz/index.php?page=podpora

Hi Mike Thanks for the info. I'll have to check my infini's version. If I may ask, since you're a reseller / installer, do you have access to firmware and software updates or do you know if there is a way to get updates or a site where we can download updates from? Thanks

Hi Chris That is quite possible since mains voltages and frequencies for example differs throughout the world. Don't they mention anything about firmware upgrades in the Aussie forum?