farmer barnes

I hadn't thought of doing the two sides in parallel. It makes so much sense in my installation. Thank you very much @PsyWulf and @Calvin

I've kind of run out of space for north facing, unless I mount the panels almost horizontally. But I look at the sun as it goes west and I think "you know, that's a real waste of photons"

There are two kinds of "needs" in this thread. One is the compliance requirements of area in which you live. The other is your own safety needs. I know which I value more.

The fact that we haven't been babysitting our electricity is exactly why we're in the position we're in. I believe (quite strongly) that if you're going to the expense of solarising your property, solarise you lifestyle first. Do you really need your water temperature set at 65C? Do you really need to put your dishwasher and washing machine on at the same time? I've just installed a 5kw system, and I'm wondering what to do with it all. As I'm sitting here typing this on my laptop my house is using 250 watts. (BTW I used to have a MGBGT in BRG )

Wow, I thought these things were standard, but apparently not so (see bottom of your 1st diagram). Your 1st diagram indicates that that device only uses CAN-BUS only, so I'm guessing that that's what you're stuck with. Any PC/networking person who can make up ethernet cables will be able to make you a cable linking CANL and CANH between each end. Make sure you mark which end is which, it won't work if you get it wrong. As an old electronics engineer, though, I'm fairly sure that getting the interfaces wrong isn't going to blow anything up - they're just low voltage signalling circuits. It took me a few attempts to work out what was happening on my system (it was incredibly simple as it turned out) and in that time a lot of things got connected to a lot of other things in the interface cables. And then hey presto, it worked. I haven't bothered trying to work out what RS485 can or cannot do differently to CAN-BUS - my Sunsynk-Hubble combo only works with CAN-BUS so I haven't needed to. Maybe someone here has?

I thought I knew how MPPT works, but now I'm in doubt. I have a situation where my north-facing panels only get sun starting mid-morning and lose it mid-afternoon. I have a place that I can mount east and/or west facing panels and connect them to my MPPT2 interface (Sunsynk 5.5kw). But now I'm wondering. As I understand it, if I connect the string half east and half west facing, the out-of-sun bank will kill the whole string. Would I be better off putting them all facing the same direction (east or west)? I have the battery capacity to see me through the non-productive period.

I wondered about that too. I know resistors work like that - if the manufactured resistance of a 1k resistor is 990-1010 ohms they market it as a 1% tolerance, if it's 950-1050 it's a 5% etc. You think you're getting a better quality resistor, but you're not, it just came out closer to its nominal value than others. So yes, it's a thought.

They're not called "solar" systems for nothing. Everything degrades in the sun - mainly due to UV. So connectors will corrode, at the back of the panel and the bayonet type connectors. Even wire itself can degrade over time, as moisture creeps in and starts attacking the individual strands in your wire. But I've been wondering about fault finding a panel arrays too. Especially on panels mounted flat on roofs. I'm surprised someone hasn't come up with a solution for this yet. Or maybe someone has?

5w in 540w is less than 1%. I can't believe anyone is tuning their system that finely - a bird flying across the panels could cause a 1% difference. And they're the same physical size as well. 10% difference I could understand, eg 540w --> 600w, but as it stands I don't get it.

I just found this. Good description of PVs in parallel, use of multiple MPPTs etc. Enjoy. https://www.solarpowerworldonline.com/2014/02/dual-mppt-defined-understanding-mppt/MPPT provides the installer,all using a single inverter. BTW there are lots of other good articles on this site. Jay

Why would you want them all on one MPPT? Not saying you shouldn't, not saying can't I just can't work out why you would, when you've got two MPPTs available to you on the inverter (I think). Jay

Can any one tell me why there are so many almost identical panels being offered by the same company? I'm looking at JA at the moment, but I know that Canadian Solar at least do the same thing. JA have list a 365w & 370w, a 380w & 385w, a 455w & 460w, and a 540w & 545w. This feels like an incredible small difference in spec to warrant a whole different part number etc. I haven't pulled the full specs and looked a power delivery curves and stuff, and I wondered if anyone else has, and what you found. They're all the same at a basic spec level, ie mono, perc, 144 half-cell etc. Jay

I'm an electronics engineer not a power engineer, so the following may or may not be relevant, but I've worked in several places around the world and this definitely happens. "Earth" is not the same everywhere, and it's not necessarily the same in any one place all the time. You can often measure a distinct E-E voltage between two earth spikes depending on their distance apart and the conductivity of the soil, especially between wet and dry. So quite where one binds earth and neutral in a distributed (eg farm) environment like mine always bothers me We have an earth spike at every DB (Eskom in, houses, shed, pumphouse etc) with EL units protecting everything. The one thing I haven't yet done on my new installation is install the E-N link relay, because frankly it bothers me. Not connecting netralsin a small system I get, but I've had some fairly serious tickles in my pump house because of untied neutrals, especially when drawing fairly large power across fairly long distances. Also, floating neutral voltages are a major potential source of RF interference (that used to be my field), upsetting TVs, radios, walkie talkies etc.

Wow. I just turned mine down from 55 to 50 because I thought "what a waste". Horses for courses, I guess. I wouldn't bother with power heating my water at all, but my wife seems to think 6:00 is the perfect time for a shower.

That last paragraph is so not my experience. When I started getting close to buying my new system, I started going to visit companies that looked impressive on the Internet. But after seeing two suppliers working out of their garages, and a couple more saying "well, I can get you anything, they're all the same inside anyway", then I said no. I have one requirement of a supplier - there must a reasonable chance that they'll still be around in ten year's time. Else what's the point of the warranty?

BTW think carefully as to whether you want to go totally off the grid. Eskom will always provide a useful, if expensive, backup for me. And if you buy (and configure) the right system, then you will be able to run all of your appliances at the same time, but like I said, learning not to is the key.

I've had small scale solar for a while, but have just upgraded to a Sunsynk 5.5 inverter and Hubble AM2 battery. I'm slowly adding more and more load to the system, but at the moment I have the whole house including 2 freezers and a fridge/freezer (we're out in the country, this saves us too many shopping trips), washing machine, dishwasher, all the standard hifi, TV & computer stuff, plus hairdryer, vacuum cleaner etc when needed. Mind you we have been careful of the years to buy eco-friendly appliances. We use solar heating, but the geyser backup is connected to the inverter and works fine. We don't have a conventional stove, we cook on gas, including boiling water, but we do have a microwave, coffee grinder etc which are all on solar now. I put in solar for my lights years ago, and I've kept those separate, because when all else fails you can do a lot of stuff if you've still got lights. That's just one small panel, one battery and a 600w inverter (I think - I've haven't looked at it for ages, it just sits there and works). I just tried my house pressure pump on the new system - we have to pump our own water on the farm, so we need a pressure pump (as well as a borehole pump to lift the water). Very frustrating to have no water pressure when the power goes out. But no more - it's working fine on solar. I also just put our small irrigation pump on (about 2kw, I think. It irrigates our two house gardens and our two orchards, but not all at the same time!), temporarily just to see, and it was fine, but I've taken it off again because... My limitation is PVs now. I only have a theoretical 1.8kw of panels, although they seem to only run at about 1kw (according to Sunsynk's monitor) A lot of people seem to forget that there's two side to this game - how much power you use, and how much power you generate. I look at it like this. The inverter limits how much peak power you can take, the battery limits for how long you can take that power, and the panels limit how often you can take that power. Very simplistic I know, and ignores some of the facilities in hybrid inverters, but I've used this to explain solar to a lot of people, and it helps them "get it". The other thing that people don't get is learning to "live solar". Like a shower in the early morning? Fine, but then either have a cold shower or pay money to heat the water. The solar way is to wait until the solar water is hot enough. Similarly with appliances. You may not be able to run your dishwasher, washing machine, coffee machine, vacuum cleaner and gaming computer all at the same time. Tough! If that's important to you, cough up and get a bigger system, or stay connected to what's left of Eskom. Now I'm beginning to look at solarising the main farm, borehole and main irrigation pump etc. I wish I could do without the inverter and use a DC pump, but there are issues with that, one being theft if the system if out in the field! I'm stuck at the moment on sizing 3-phase soft-starters for pump motors. I know how they work, I know they do work, but it's difficult to size the inverter require because I can't find by how much they limit that in-rush current when you start up a motor. Can't find it yet 🙂

@jumper excellent tip. Thanks.

I know it's not critical to operations, but I'd like to get this giving a meaningful figure, if only for bragging rights 😀 If I remember there are three options in the configuration, one of them being "straight". What do I put in there?

Just to try to bring this thread back to my original question, how did/will you choose your PV brand (as opposed to supplier)? Or did/will you choose your supplier first and go with their preferred brand ?

Oh cool. You've saved me a trip up the ladder, and when you're my age and shape, that's a good thing 😀

@jumper have you had a problem with renewsys panels discolouring? See photo.

@JohandupI'm happy for you. It didn't go quite as smoothly for me.

@jumperthanks, I'd seen that. On the subject if renewsys, have you had any panels discolouring like this?

I'm seeing the name "JA" a lot nowadays, but I don't know/can't decide whether that's because of aggressive marketing, whether it's based on quality, or it's simply a matter of "follow the herd" (no offence meant! 🙂). Seems like every panel I see advertised comes from China now, and I dislike monopolies. Pity LG quit the PV game. I understand they were very good.