display_Name

Ok, I've been down a rabbit hole of looking at inverter options for the SolarMD. I'm struggling to like any of them. I mean, I really like the Sunsynk inverters, but that 13A input current has me concerned as it means I'm sitting with a smaller PV array size for a more expensive inverter (6500W vs 9600W). I'm also limited in panel size it seems. Question time... let's assume I am looking at the Sunsynk inverters... if I am looking at panels that are 13.7A, and the Sunsynk MPPTs are 13A, does the inverter clip the remaining current or does this damage the inverter? And if it clips... how much efficiency does the panel loose? I called Sunsynk, and they didn't seem enthusiastic about running a 13.7A panel on the 5kW inverter... but the person I spoke to didn't sound super confident in their answers, so wondering if there is something I can read up about this. I really don't like the other inverter options I've seen that support SolarMD (including Victron, which I though I was really going to like until I dug into the MPPT charger sizes, and there is something about having 5 different boxes sprayed all over my garage wall that I don't like instead of one inverter). My next option was to actually consider other batteries, which I was really hoping not to do because I was set on SolarMD... being based here in Cape Town and all. I looked at this, and in there I see a Dyness battery which I can find locally. Does anyone have experience with Dyness? I see they are 6000 cycles as well. Are the CATL cells? Is there good local support in the event of an issue with the battery? EDIT: Ok, so after some more searching around, and looking at some other battery providers, including Hubble and Volta, I'm thinking possibly the following: 2 x Dyness Powerbox Pro 10.24kWh 2 x Solis S6 Pro 6kW Advanced Hybrid Inverter 32 x Jinko Solar Panel Tiger 560W Mono-Facial The Dyness batteries are only 0.5C, but I'm considering 1 per Solis Inverter, giving me a combines 10kW peak power from the batteries, which would be what I'd be getting from the SolarMD batteries, but I'd have 5kWh extra capacity. Solis has the Dyness Powerbox on it's support list, so that's a win at least. What am I missing?

Ok, so an update on my side. Contacted SolarMD. The Solis inverters don't communicate with the SolarMD batteries. They would need to measure voltage. Not ideal so I'm going to look at other options. Will revert with more in the next day or 3 after some more hunting around. I see online that Deye have a 6kW unit, but I don't see any suppliers here in South Africa. Their 5kW units only support 13A input current, where the Solis 6kW supports 16A. I have some more homework and will revert once I've done this. Would love to see when these arrive on the market. 18A input current on the 6kW: https://www.deyeinverter.com/product/hybrid-inverter-1/SUN3-6-5-6-7-6-8KSG05LP1EU-3-68kW-Single-Phase-2-MPPT-Hybrid-Inverter-LV-Battery-Supported-2344.html In other news... https://mybroadband.co.za/news/energy/532079-solar-silicon-prices-plummet.html

Brilliant, thank you. So If I sum up the AC column and divide by 365, I get to 65.6kWh per day, which is actually not far from my estimate of about 68kWh per day on average. This is fantastic validation.

No we're aligned. The peak value there of 4.7 to 6 (Western Cape), is what I derated to 3.8, so I am assuming that I will only get an effective 3.8 hours of peak sun... just spread out over the day and not in exactly a 3.8 hours period, meaning I'm probably not being limited much by the inverter's 12kW limit too much. I assume that this (Mid-Summer): and this (Mid-Winter): Taking the angle of the sun, the rainy days and all the other negative stuff would equate to the 4.7 - 6 value... and I'm dropping that to 3.8 because of orientation etc. Does anyone here perhaps have any actuals they could share of what they're getting in terms of kWh per day per kWp, over the year? I'm all in theory land at the moment.

Just able to get back to this thread now. Really appreciate the comments here. It provides an opportunity to correct any thinking I have. I've tried to shy away from extreme optimism, and I also have some unknowns which will create some variance. I'll list them here as you may have some answers for me. So I took my average consumption over the last year (some heavy months like July / Aug compensate for some lighter months like Jan / Feb), and on average I'm on about 32 kWh per day (works out to about R96.40 cost per day). In terms of panels, I'd have 560 x 32 = 17.920 kWp. I used the factor of 3.8 x kWp to get to Generation of around 68 kWh per day. What I don't know... is what the impact of the clipping will have on that value of 3.8 (I've tried to max out the 17.9kWp of panels because if you assume a poor power factor of 3.8... I'm not sure the panels are ever really taking the inverters up to max output of 12kW to grid). We have 14 hrs of sunlight a day in midsummer and 10 hrs a day in winter, so 3.8 is fairly low, and I want to keep it that low to be conservative ideally. In winter the panels are probably not pushing anywhere near 12kW taking cloud and Azimuth into account, and in summer we just have sun for so many more hours in the day. This leaves me with about 36kWh on average per day spare, which would nett me R37.54 if we assume Eskom (78.98c) + CoCT (25c) = R1.04. So if I take my average daily difference (R96.4 not being spent + R37.54 being earned) I should get to about R133.94 per day or R4152.14 per month change in my current position. I don't know what impact clipping will have on my calculation above, and while I tried to drop the avg generation of 4.8kWh per kWp down to 3.8 for safety, maybe that's not enough (shrug emoji?). I need to draw a line somewhere, so that's an assumption that may hold out to be true or false. It would be great to get some stats on your measured kWh per kWp on average over the year and get a sense of what a real world value could be. Ok, now for cost: From what I can find online: Panels: Jinko 560W panels from inverter-warehouse.co.za: R1,695 per panel. 32 panels = R54,240 Inverters: Solis S6 Pro 6kW from thepowerstore.co.za: R19,585 per inverter. 2 inverters = R39 170 Battery: Solar MD 14kWh from solarspot.co.za: R62,500 (I've seen them for R60K, and I think with lithium trending cheaper, and the new SolarMD factory happening this year, I expect this to continue the drop over time. Mountings: Axe Struct: They helped me get the part list I need for 32 panels in the layout I need (they have a configuration tool that's pretty good), and I got the quote from ARB for the parts: R28,569.11 This gets me to R184,479.11 Now I need cables, fuses, DB boards, and the actual installation. I've priced most of this, and it's not that much, but the big variable... what will installation cost me? If I had to thumb suck and say shipping, cables, fuses and installation could cost me R40 000 (I may be high or low here... I just don't know what the remainder will cost me... hence some estimates), then I'm sitting at R224,479.11 If I do the divide (R224,479/R4,152.14), I get 4.5 year payback. This is different to the 3.9 I had above because I removed the Solar Tax incentive that I still had in there (that lapsed in Feb this year), and I added more buffer for shipping - also guess work. I really don't know what to expect for the install cost quotes here, and that's the main variable at play here for me. I mean... I really want to do most of the DC side of the installation myself, including mounting the inverters, battery and panels (excluding AC wiring), but I'm not sure how much I'm allowed to do, and where I have to bring in an installer / electrician, or what that cost would be. Interesting note: What really struck me, is just how far the equipment costs have dropped in the last year. I have been tracking equipment cost over the last year for my install. In July last year, the SolarMD battery was R85,000, Sunsynk 5kW inverters were R28,000, 555W Jinko solar panels were R2,300. That R184,479 figure that I came to earlier (excluding cables, shipping, install) was R234,000 in July 2023 for a smaller system of 28 panels and 10kW of Inverters. SolarMD cost drop for the 14.3kWh In July 2023, the battery was R85 600.47 (arb.co.za) In August 2023, the battery was down to R76,923 (jcsolarpanels.co.za) In December 2023 it was R73,363.88 (jccolarpanels.co.za) At the moment I can find one for R62,500 (solarspot.co.za, with others not far off this) Anyway, apologies if that's too much detail, but that's my thinking anyhow. I'd appreciate any holes being poked. I'd rather them poked here on digital paper where only my fragile ego can be dented, than in my pocket during the install. Any insight on my unknown costs would be really appreciated.

Oh definitely. I was hoping that by having 12kW on the inverters (limited by 10kW peak from the battery in the beginning), I'd be pretty close to supplying what municipal mains can supply for my house (13kW from what I understand). Great question! Check my logic for failure please:) When I do the math, as weird as it sounds, maxxing out the system panels pays it off way quicker when pushing all the excess to the grid as the panels and mountings are the cheap part. Let me explain my thinking: Essentially, I want to sit as close to the municipal max (I've been told it's 13kW for my house) that I can. Firstly this is so that I can better absorb the peaks Bobster refers to. With 2 Sunsynk 5kW units, I'm at 10kW. In theory this matches better with the SolarMD battery's max. However I can see myself adding another battery at some point, allowing me to fully utilize the 12kW peak of 2 x Solis 6kW inverters and have better backup for winter periods. Then from a panel perspective, I want to get as close to that as possible, so if that's 4.4kWp on each string facing East / West, then midday it's probably going to clip a little and max out at 6kW (hopefully at least some of the time). In winter, I am hopefully never drawing from the grid, and thereby not paying the more expensive rate, improving my differential. Secondly, I'm now maxxing out what I can send to the grid (as close to municipal mains threshold). This is where the payback figures flip around. Because I've already committed to 2 x 6kW inverters to handle peak load, adding panels becomes the cheaper part that really drives down the overall payback period when feeding back into the grid. Back of the napkin calculations taking an average production per day (averaged over the year) of 3.8kWh per kWp (apparently cape town is around 4.8, but I'm derating that because I'm not going to be at a perfect orientation), I should reach payback in 3.9 years. Even if that extends to 5 years, that's a solid payback period. This is without the eskom price increases coming. Second to this comes the warm and fuzzy feeling of contributing a little to solving the load shedding issue in a tiny tiny way by creating more supply. Anyway, that's my thinking... Bottom line, even though the overall system cost is more expensive, it's payback period drops by several years if I do it this way.

Brilliant. Yeah I think I'll go with 8 per string then. From an inverter perspective, I'm fairly comfortable with the Solis inverters, and have been in touch with Solis, understand the return process if needed, who the distributors are etc. But... I've seen a number of posts on Solis here on the forum... any reason I should not be going Solis? My thinking is that I want to keep this simple, and just put the whole house on the backup load (I'll put them in parallel). I don't think we'll go much higher than 6-7kW draw, and the SolarMD can max out at 10kW, so I shouldn't be pushing that to max. I can always double up on that if needed down the line. Bad idea?

Loving the replies, thank you. My thinking is that each inverter has 2 MPPTs... so put the panels for one of the MPPTs facing East (on one string), and the panels for the other MPPT facing west (on one string). I.e. only ever using 1 string per MPPT. Then do the same for the second inverter. If I instead split 2 strings East / West from one MPPT, would I not be leaving MPPTs on the table? Or are you thinking smaller strings?

I'm ready to press go on my install (very excited). Would love some thoughts on the chosen setup, and if you have any recommendations for installers in Cape Town Northern suburbs, please DM me. Here's what I'm looking to set up: 2 x Solis 6kW Inverters (S6-EH1P6K-L-PRO) 32 x Jinko Tiger 560W (JKM560M-72HL4) Axe Struct Mounting system (Railed Roof Top) SolarMD SS 4143 14,3kWh Mock up of the roof attached. Mostly East / West, I've added summer / winter sunrise, midday, sunset lines to show morning and afternoon sun. I can't mount on the north facing roof (geometry won't allow). My thinking is to have 4 strings of 8 panels per string, with the strings of each MPPT split East and West. So MPPT1 String 1 East and MPPT 1 String 2 West. Was looking at 5kW Sunsynk inverters initially because the software is apparently pretty good, but the panels I'm looking at are 13.6A (over the Sunsynk rating of 13A), and the Solis 6kW at the same price looks like it makes sense with the additional headroom. Unless I'm missing something. The equipment above comes to R185K excluding shipping. I'd still need fuses, wire, connectors, DB board, breakers, conduit etc etc... and of course the installation. Does this look about right for a setup?

Hey I'm trying to get a sense for which cost effective mounting solutions I could use. I'm looking to install potentially quite a few panels (32), so I am trying to bring the cost per panel down if I can. Please critique my thinking, and if you don't mind, share what you used as a mounting solution? It's a clay tile roof. P2000 unistrut rails (Galvanized & Slotted) example: https://www.solar-europe.co.za/product/inge-p2000-unistrut-galvanized-slotted-6ml-us008/ Roof Bracket example: https://umoyasolar.co.za/product/solar-adjustable-roof-bracket-430-stainless/ Mid Clamps example: https://umoyasolar.co.za/product/mid-clamp-for-unistrut/ End Clamps example: https://umoyasolar.co.za/product/end-clamp-for-unistrut/ I'd need a few other pieces in here, but I'd be keen to hear some suggestions.

Thanks. I still need lots of reading. So many questions in my head right now regarding everything.

If it was important to keep the Max wattage per MPPT to below 4800W (as TaliaB said above), then on my roof it would likely make sense to keep them both at max panels, and that would mean balancing them at 8 panels a piece. If I was able to go over 4800W, then I'd probably have one MPPT with more panels, but at this rate, I want to max out each one. Next (last? probably not last tbh) question on strings etc. The MPPT supports 2 strings. The strings need to be the same size if I use 2 strings. I'm probably going with one string per MPPT, and putting all 8 panels on the one string to max out voltage for earlier morning kick in, and for winter etc. However... let's say I want to utilise another portion of my roof because maybe I can better utlise some sun for a portion of the day... can I face 2 strings on a single MPPT in different directions? Would that not have the same effect as making the two strings on the one MPPT a different size? And to your point about East / West... I do have a bit of an East / West split... with the one side getting more morning sun, and the other more afternoon. Was wondering if I could put one string from each MPPT on each side of the roof, or whether I put one MPPT (single or both strings) on each side?

Ooohh.... this is great, thank you.

Ok yeah, as per GreenFields... perhaps 8 panels (if they are 550W) per MPPT would be a sweet spot... and that would only be a Voc of414V and max power of 4400W.

Ah, I missed the 2/2. Thank you. What is the giveaway that it's max power/mppt is 4800? Is it just that the max power is halved because it's 2 x mppt? Then do you mean that each string on the same mppt must be the same, but the second mppt can have different string size? Related question... Is it better to use a single string per MPPT to get a higher minimum voltage? My roof is a peaked roof and I will have panels on 2 sides only... so no need to have 4 different orientations. So orientation aside... my assumption is 1 string used per MPPT?

I was reading some reddit posts on some solar installations, and they were talking about how they had to leave some space specifically for firefighter access to pass regulation in their state. That got me thinking... what are the laws / obvious considerations for access that I would need to consider while calculating how many panels I can fit on my roof here in SA? Space from edge of roof etc. If I can properly calculate usable roof space, I can choose the correct PV panel size to maximize coverage. Are there any links that you can share where I can do some reading?

Thank you. I'm busy plotting this all out in excel at the moment... and I'm also looking at smaller panels as well (460W range). Some of it will come down to roof space and how much space I might need to leave near the edges. Was also thinking of dropping string size to keep voltage within MPPT if I'm going to be limited in any case by having one smaller string. I'll revert here with my thinking if you don't mind having another look. Thank you.

Brilliant, thank you.

I've been trying to wrap my head around the system I am looking to install, and I'd appreciate some input if you have some to spare please:) For a guide, I've been following this site: https://solardesignguide.com/calculating-string-size/ It feels like a fairly good place to start in getting my calculations right, but there's something fairly trivial that I'm not understanding. By way of example, let's assume a Solis S6 (Tech Specs: https://drive.google.com/file/d/19Ay6UZRCvoYI2LsUeAHu-b2gQaiDDdjx/view) and Canadian Solar HiKu6 Mono PERC 550W (Tech Specs: https://static.csisolar.com/wp-content/uploads/sites/9/2023/09/26103742/CS-Datasheet-HiKu6_CS6W-MS_v2.8_EN-2278mm-1.pdf) The inverter's Max Input Voltage is 600V with the MPPT range between 90 and 520. In my area, the coldest day I can find is about 8 degrees C. So with a temperature coefficient of 0.26%/degC, the Voc in theory can jump from 49.6 to 51.8. That gives me a theoretical max of 11 panels (11.5 panels rounded down). 11 panels gets me up to a max of 6kW. The inverter spec has a Recommended max. PV power of 9.6kW. The inverter has 2 strings. I guess my questions are 1. Are my calculations correct? 2. Is Max PV Input voltage actually 600V on each string? 3. Would this mean I have a second string that I can add up to 3.4kW? 4. Should I be looking at 2 equally sized strings? Should I be looking at a a different spec PV panel to achieve the best matching where I'm maxxing out production within the right limits of the inverter? Would be happy to move up and down the range to get the optimal PV panels sizes to max out the inverter (the panels will never be in the perfect orientation to max it out anyway, so I want to ensure that I don't set it up too far under what I can get). Also going to run similar calcs on the sunsynk 5kW, but will post a separate question on inverter comparisons (software etc). Right now my brain says 2 x 6kW inverter with 16A current > 2 x 5kW inverter with 13A current. I know this is a mouthful to read, so any insight here would be amazing, thank you.

Appreciate the reply. I was thinking either the Sunsynk 5kW Hybrid (x 2), or today I saw a very good write up on here about the Solis S6 Pro (perhaps 2x 6kW). I suppose I'd need to reach out to those companies ad check compatibility.

Heya... new poster here (been reading up on here for quite a while). Over the last year, while I save up, I've been tracking the prices of the system I'd like to put together. I'll probably make another post asking for input on my thinking, and finding an installer. Anyway... until now, I've been watching the price drops on the SolarMD 14.2kWh battery with great interest. Tonight I saw a New Sphere 5.12kWh battery, and 3 of them come in way under the SolarMD 14.2kWh. I can't find anything online about them. They are obviously a rebranded battery from China or somewhere, but does anyone have any information on how well they work or have them installed? Would stacking 3 of these together beat a SolarMD 14.2?