Arandoza

Use a Geyserwise with 2kw element connected to my first online evacuated tube geyser to heat water to 65 deg c from 9:30-14:00. Usually from 9am we are generating around 3kw plus, so can safely spare the power. We use sonoff basics via timers to max out the solar without switching back to grid. On cloudy days one simply turns of the Geyserwise, and powers it back on once the clouds have dissipated.

Hello All, I would like to learn how to correctly build a PV Array combiner box. Obviously they differ dependant on the array configuration and amp / voltages of the array. We use Axpert 5kw inverters and would like to have 6 strings per combiner box, each string with 3 x 275w panels. (50% Oversizing for bad weather, and to compensate for winter.) I understand that the combiner box plays the following roles. 1.) Protection : Fuses for both Positive and Negative feeds from each string. 2.) Protection : Lightning and or Surge protection, which would go to a separate ground/earth spike. 3.) Disconnect : So that one can disable a individual string if needed, I assume MCBs are used. 4.) Output to inverter would use 6mm or better cable, to reduce losses and endure the combined currents onwards to the inverter. What I would like to find out is how one should go about specifying the Fuses and Disconnects (MCBs) as well as the Lightning / Surge suppression and any other considerations. The 5kva Axpert operates on 60-145v(Max Rating) per array, but typically is 65-110v, and the 275w Panel values are as below Open Circuit Voltage (Voc) 38.38v Max Power Voltage (Vmp) 31.34v Short Circuit Current (Isc) 9.29a Max Power Current (Imp) 8.77a How does one then calculate the correct components for the combiner box? I am sure many folks are interested in this topic and I expect it would be great if we had a Tutorial / Guide on how to design and spec combiner boxes If there already is such a guide please point me in its direction.

Interested. Have sent you a PM via forum.

From everything I have read about batteries and charging regimens, it don’t think it would be a good idea. Even batteries that are of the same type and brand vary in their abilities to charge / discharge, and it’s not recommended typically to add a battery bank of the same type to a bank that is the same but more than 6 months older than the existing bank. If you have two different types of batteries calcium and deep cycle they will most likely have different charging and discharging characteristics. And when the calcium’s fail, probably before the deep cycles then the deep cycles will not be correctly charged and potentially could get damaged as the calcium’s probably start to create more resistance in the two battery banks. I think either way you will shorten the lives of both banks, in the long run. Rather sell the calcium’s and get a larger bank of the same model / brand / age batteries for a reliable solution, and without risking replacing your batteries prematurely, they are expensive to replace.

I sourced these relays from AC/DC for use with my sonofs. Not sure if applicable of suitable to your application, but depending on which connector you use 1-2 or 2-3 they can be connected to be either normally open or normally closed. The two red wires at the bottom are going onto the 220v relay coil.

For my RCT Axpert’s 5kva units the manual recommends a minimum of 200ah for the battery pack. I expect due to discharge rate, when under load.

Not sure if there is a Linux version of watchpower. For monitoring and control have a look at https://iccsoftware.co.za/ works with quite a few invertors.

If you are looking at monitoring your a axpert maybe have a look at this. http://iccsoftware.co.za/ it’s locally grown

Try Zettys centurion

Usually the axperts have a serial and usb output, mine came supplied with the necessary cables as well. If you want to use the serial you will also need a serial to usb port cable. You should find the ports at the bottom of the axpert where all the other cables enter / exit the unit.

Hello Soic, I think you forgot to add your volts together per array, 76v x 4 = 304v per array (8 panels)? You added the watts and also the amps together but not the volts. if you combine the 3 arrays in series it will give you 912v if you connect them in parallel it will remain 302v if not mistaken.

Hello Alkafak, The interesting thing I noticed with your photo is that you appear to have two frequency numbers showing 47.6 hz and 51.5hz, not sure if you are running a single or three phase system? Or if your mains power is being supplied by a Generator? Most of the APC type UPS's are quite sensitive to the Frequency variance, and sometimes only allow for a variation of 49.5 to 50.5 hz variance, for a 220-240v 50hz system, otherwise they disconnect the mains input and run on battery, and they are also sensitive to phase rotation (the order the phases are connected) on three phase UPS's. I wonder if this is not where your issue lies? But am not familiar with the Infini 3+ and what frequency tolerance it allows?

http://www.communica.co.za/catalog/Details/P1239073412 add a 15amp plug and a Janus connector to one of the above sonoff pows and you have a on/off switch with power metering, / logging, provided the sonof pow can connect via WiFi to the internet. They seems to be able to measure fairly low wattages and seem to be fairly accurate.

Hi All, Just a bit of feedback, on my original problem. The hot wires I upgraded my cabling from the second array to the 10mm2 cable and also found that the positive PV cable breaker - the cable clamp on the breaker, despite being tightly screwed in did not appear to grip the cable with much force, so I suspect I was also getting a loose connection where the cable entered the breaker? Also adding to the problem. Since replacing the 2nd array cable and the breaker, the new cable definitely runs cooler, around 25 deg c, when compared with the first arrays cable, about a 10 deg c difference. Also bought a IR temperature thermometer, the point and shoot type, and find a big difference under load of the cable and breakers compared to the first array. I still need to replace the first arrays cable, to 10mm2 and also replace all the breakers as @SilverNodashi recommended, on the D.C. Array side. Also I would like put together a 5 or 6 string type combiner box, but the costs are slowing me down, and I will need two of them any suggestions on where to buy the well priced components for a diy combiner or already built version will be welcome. Thanks to everyone for their input, it's always appreciated.

Hi @Kalito This is the software http://iccsoftware.co.za/ it all started here on the forum, A few folks on the forum got the idea going and I think @Manie is developing and updating etc. And it was built for the axpert / infini inverters, and they may add support for more inverters over time, if not mistaken. it works really well and I like the pi version, but am still using an older pc version presently.

Evening Chris thanks for the Reply. The 4 (3000w -250wp) (or 5 (Mixed 260&250wp 3780 total - Not all facing the same direction so unlikely to get to Max - 3 North - 1east - 1 west) ) strings are connected together (parallel-using MC4 Branch Connectors) on the roof and single 6mm set of PV solar cables (Pos+Neg) come down into the garage. For each array. So two sets of 6mm Solar PV Cables. And the 9 amps is about right per string. Originally I was concerned that the MC4 connectors are only rated to about 30 amps from the research i found on the web. Also the Panels only come with 4mm pigtails off the panels. And I had thought the MPPT would keep the voltage higher and lower the amps so this may not have been a concern? Hence the 6mm Solar PV Cabling was used for less resistance, heat etc. And the MC4 Connectors amp rating made me look into combiners but they too only seem to use 6mm PV cable in the box for each string and then from the combiner to inverter? Which did not seem to address the amp rating concern. Will definitely take up your advice on the combiner box and investigate thicker PV Cable sizes, I estimate the runs to be around 30m at max (Array1) and 20m (Array2) across the roof(s) down to the garage.

Hello All, I wonder if you can give us some advice? Recently one of my two Solar arrays has started tripping the 63a 220v Circuit breaker on the PV array input on my second Axpert inverter. And the PV cabling (6mm) to and from the breaker box's and arrray's is really hot to the touch (Maybe 40-45deg?) I take it this not a good thing (one can see the power dip on PVoutput below when the one array trips out.) This appears to only happen when I am pushing the teamed (2) inverters to max capacity, and they are running at 4600-4800W PV input for about 30-45 mins, then the breaker trips, on the 2nd inverter with the 5 string array and the breakers are hot, as are all the cables, for both arrays. What is the normal operating temperature of the PV cables typically? What do installers see in the field? My configuration is 2 X Axpert 5kva inverters paired on a single phase. 8 x 245ah TE35 Trojan battery bank. 1 array x 12 panels of 250W panels 3 Per string, 4 strings for the original inverter. 1 array x 15 panels of mostly 260W panels, So 3 per string, 5 strings for the array, 1 string maybe a set of 3 250w Panels. Each array runs its own set of cables and its own breaker box, to each inverter via a dual 63A (220v) trip switch box, on both negative and positive, on each array. Also on AICC I noticed that the second array and inverter seems to be running at 80 volts and around 46 amps, and the first inverter is also running around very similar Volts and Amps on the first array, when the PV trip occurs. I having been thinking of upgrading the safety protection for the PV side, and have been looking at things like combiner box's but would really like to build my own. And I don't seem to find good reading material on how to spec the fuses, and or trip switches, and lighting protection for such a combiner box. Any tips here would be appreciated.

I started experimenting with the Sonoff switches one can get them at communica http://www.communica.co.za/Catalog/Details/P0240254864 They are "hackable" but haven't started to go in this direction just yet. Want to automate power switching via wifi and raspberry pi using mqtt to read available solar power and then utilize as much as possible without overloading the inverters real time production capability. I would use heating to burn off extra capacity when's it available during the day, but if clouds Arrive it would be nice to read via mqtt the axperts pv and load output and ensure that the pv input is always a few hundred watts higher than the load, as conditions change the app should be able to drop Non essential heating / cooling loads etc, ideally with the system being very dynamic and quick to read current conditions. A type of Home Energy Management solution if you will. Also toyed with a pi and 8ch relay board with home assistant on the pi, it was pretty good, but the electrical wiring to the 8ch board was not practical. Liked the way home assistant worked with the need for Internet / cloud.

As far as I recall the 5kva axpert recommends a Minimum of 200ah battery pack, for a single inverter, 400ah for 2 in parallel etc. 200ah is not that much considering one probably can use only 25 ah - to Keep the dod low and then also to allow any loses, and inverter consumption as well.

Hi, To add to the comments we use a LG Direct drive 9kg front loader on a quick wash, on cold water setting only and spin speed 1400 rpm to reduce drying time as well, definitely recommend this it really helps in Winter when nothing wants to dry, without a tumble dryer When running I have never really noticed a spike in consumption, when viewing the inverter it seems to be running around 150 watts higher than usual but with all the other loads running i can't easily say exactly how much it draws, but it appears to be very light on power and no big spikes. It's also a+ rated - by chance . Model F1403FD5 If the water temp is increased from cold wash I'm sure the power would spike big time, I expect it has a 2kw heater element. As a plus most of the kids school wear including blazers and sports kit recommends cold wash and I can't say it has adversely affected the cleaning ability. But no heavily soiled clothing or greasy overalls being washed Happy shopping

Hello Ridiq, I too am based in centurion. My panels were also at a fairly steep angle of about 28 deg also facing north. I too found that there was a notable top end drop from winter to summer. I cleaned mine and found an improvement, maybe around 10%. But the bigger issue I found was that if I lowered the tilt angle to nearly flat, the power improved once again, although with all the cloudy weather it's been hard to see via pvoutput.org daily figures. However if one loaded the axpert heavily at the same time of day, and compared what the panels would generate it seemed to make a drastic difference. Also many of the tilt angle calculators on the web suggest that a horizontal panel in summer and slightly tilted in winter will give better results for the centurion / pta region due to the arc the sun makes during the year. My own observation has been in winter the sun rises only till about the 11am position, if you face north. However in summer it appears to go to around the 1pm position, which when overhead at midday almost starts to shine downwards from behind the panels when at 28 deg. However when laid almost flat they still perform well. I also find that in summer my west facing roof gets good late afternoon sunlight, in winter almost nothing, have been contemplating adding six panels to this portion of the roof to extend my sunlight hours in summer A further thought. Is there possibly any new shading ? Trees that have grown ?

Hi, 800watts seems very high for a fridge a freezer and some lights. If the fridge and freezer are old it May explain the high usage. I moved to Bosch A++ fridge and seperate upright freezer each consume around 90watts each when running and freezer has a 16 hour period where it can be without power and you won't loose food? I guess provided you don't open it Got my load down from also around 700w with over/under and a side by side Fridgemasters down to around half of that, with lights. Fridges last longer than the batteries, so if these are the culprit for high usage, consider A++ or even better A+++ if you can find them at the right price. Don't consider A+ as the A++ is typically three times more efficient than a A+ based on the info I could find when I changed mine. Also for interest my axpert 5kva has never generated over 14kwh a day and it has a full complement of panels, but not much storage only 245ah. On a bad day I can get around 7kwh out of it. To achieve the 30kwh per day you would need at least two Of them in ideal conditions, and Lots of storage if night Time usage is 14 kWh? Which may get worse in winter with the shorter days. Lower the average load day and night and try To Maximize power Use during the day Not an easy task, but enjoy the journey.

Very sad news jdp, sorry to hear of this misfortune.

I am running glass ev tubes and it won't overheat, only if we don't use the geysers at all. We then catch it in the rain harvesting tank and reuse. If we go away for a few days, I simply shade the ev tubes with high density shade cloth, which means the geysers remain hot but far less likely to overheat and waste water, however our roof lends to easily getting to the tubes, flat roof, where the geysers are.

try metro home city Pretoria? One can buy online their prices were very good in Jan this year