Tacet

This is the part I'm worried about - the fuse holder is an Inge, which I'm not too familiar with. I'd have preferred something like Schneider or ABB, but I didn't have control over the installation. Good point - I haven't considered the resistance of the fuse itself (was fixated on the fuse holder). Ventilation slots are open and clear, the holders are mounted vertical, and the layout is fuseholder, SPD, fuseholder, SPD. I'm not at liberty to post pictures, but the warmest part of the fuseholder is in the bottom half of the older.

True - any switchgear has internal resistance, and putting current through that will always result in P=I^2 x R. That power can't really be converted to anything else than heat. I just haven't seen a fuseholder go this warm on any other installation - mine at home and the others I've measured are usually about 2-5 degC above ambient. So I'm trying to figure out at what point I should start worrying. It is a 3-phase 12 kW. But yeah, I was lazy - typed "< 700 V" rather than recalculate the actual Voc. Voc @ 0 degC is 637 V. The PV input range is up to 800 V on those. MPPT stops tracking at 650 V, but with a Voc designed for 637 V @ 0 degC the system is pretty well within spec.

Friends of mine have a Sunsynk installation with a 12 x 550 W (Imax < 16 A, Voc < 700 V @ 0 degC) panel string. The installation is working well, as per expectation, but the fuse holder is running hot (~40 degC). The fuse holder is an Inge, rated at 1000 V, 32 A. The fuse is a 20 A fuse protecting a 6 mm2 cable. We've double, tripple, fourdouble-checked all the connections; there's no loose connection. Anyone else with experience of fuse holders warmer than expected? Most I've seen are running at 2-5 degC above ambient, which I expect due to the internal resistance of the fuse holder itself. But the 40 degC we see here is close to 15-20 degC above ambient. The temperature was measured at ~11:00 in the morning on a sunny day with 5 kW solar yield.

Morning, I suspect that this must have been asked before, but my searching yields very little results. I have a Deye system on Solarman Smart, connected on the app by a normal user. Is it possible to share the plant with additional users to see e.g. the yield? Thanks!

I was about to ask the same - in our experience the structural engineers are not likely to sign off on such pronounced tilt without serious reinforcement of the supporting structures. The wind load of the panels become a key consideration. @Steve87 - are you using the Enerlog for monitoring? Have you been able to find a means (excluding Home Assistant) of remote control of the inverters?

Hi all, I hope my searching skills didn't let me down, but I can't find the answer to what is probably an easy question. If I have a Sunsynk 12 kW hybrid inverter, how does it handle the balance between battery charging and load (assuming night, so no solar)? If my load is 10 kW, does that mean that I have only 2 kW left for battery charging? I'm trying to see what a realistic maximum constant power load is, taking loadshedding's recharge requirements into consideration. Thanks!

Yep, that is the concept I use at home (my personal install is a Victron Multiplus II - works extremely well). Most telco sites, though, has too little roof space to supply even close to the full load from solar. The loads are usually connected to the batteries via an LVD that is controlled by the rectifier. Under normal operation the LVD will be closed. The batteries themselves are a fair range: 2 V VRLA, 12 V VRLA, lithium...

Some perspective - most operators are preparing for >15 kW loads for each mobile site when 5G comes. I've seen small 19", 5U rectifiers that can do more than 20 kW. I see pros and cons to mixing on the AC side or on the DC side. Mixing on the AC side: As you say, it may well be cheaper. Extra conversion step - extra losses and extra things that can break. A really nice pro - on a site with multiple small rectifiers, a single solar installation can benefit all the rectifiers as well as ancillary equipment such as aircons. I don't think you'll be able to keep the inverters up if the mains fail, unless the solar installation/yield is larger than the site load. Mixing on the DC side: Simpler equipment, but a more difficult solution. You don't have to worry about the AC side at all. No backfeeding issues, no anti-islanding required. In case of an AC fail, the solar will still contribute. Thanks for the inputs, people! You're making me rethink my stance on mixing on the AC side - there are more benefits than I realized.

That's certainly the easiest solution, but not very efficient. Instead of a single DC-DC conversion you now have DC-AC-DC. Also, inverters tend to be more expensive than charge controllers, so it makes the ROI a more dubious deal. I try to keep work and forum separate, but this question piqued my curiosity, which is why I brought it here. The industry is telecoms, so the main reason for operating at DC is to keep the equipment permanently on batteries. A rectifier will typically be used to supply either multiple DBs or equipment racks, so in most cases you won't pull 625 A to a single load. And yes, paralleled 150 mm2 or 185 mm2 cables does happen. In some places busbars are used between the battery cabinets and the rectifiers. For high power solutions we prefer a UPS solution to carry the load until the site's EPS kicks in. Unfortunately some of the equipment manufacturers are totally happy to have 18 kW devices that can only operate on 48 Vdc.

System sizes are scalable - I'm looking at systems from 2 kW to 30 kW. I'm not worried about wire sizes - it is easy enough to bring your PV down to the charge controller at e.g. 250 V, and to install your charge controller next to the rectifier. I don't think it is quite that easy. If you simply parallel them and the output voltages are not exactly the same, the load will draw from the highest output voltage. If that is rectifier, then the solar charge controller will idle. If the charge controller tries to keep its output e.g. 0.01 V higher than that of the rectifier, the load will be supplied first by the charge controller and then by the rectifier. We often parallel rectifier systems for redundancy purposes. Even if the two rectifiers are from the same supplier, same model, in the same room (thus the same temperature) with the same configurations, you often see the load shift between the rectifiers under normal operating conditions. Those minute differences between temperature readings and output voltages makes a difference. Add battery charging to the mix: you want the existing rectifier to control the battery charge voltage and to limit the charge current if necessary. You still want to use your available solar energy to provide the load and charge the battery, but you don't want to overcharge the battery. The best idea of how to do this I have at the moment is to configure the charge controller independent of the rectifier, but with a float of e.g. 0.01 V higher than that of the rectifier. There may be times when the temperature compensation inaccuracies pushes the rectifier voltage higher than the charge controller voltage; it will be interesting to see how often that happens.

A device that takes as input either 3-phase or single phase AC, and rectifies it to -48 V DC. On the DC side it will usually connect to both load and batteries, and the user will be able to set the float voltage as required by the batteries. The rectifier can do temperature compensation and is able to limit the charge current to the batteries.

Hi all, I'd like to pick a few brains, to see what the possibilities are. The company I work for have a few DC rectifiers supplying -48 V to various battery banks and equipment. We're unlikely to go for solar as we don't really have enough roof space. However, I'm curious about the concept: how would you supplement an existing rectifier with solar? The rectifiers are reasonably good at what they do, so you'd want the rectifier to retain control over the float voltage, temperature compensation, charge current limiting, LVD control, etc. Simplest way: install hybrid AC/solar rectifier systems. Various manufacturers make them, and they will do the job perfectly. But replacing is expensive - supplementing should in theory be much cheaper. Slightly less simple way: grid-tie inverters on the AC side. However, that feels like you're simply adding unnecessary conversion losses and an additional layer of equipment. The solution is readily available even in the retail market. More efficient and cost effective way: supplement on the DC side at -48 V. I've never seen solutions designed to do this, though. I'm not even sure if it possible to do it without communication between the rectifier and the solar regulator, especially if it comes to charge current limiting. Any thoughts, solutions, ideas?... I'm guessing that my preferred way is a pipedream. If it was possible you'd probably see it punted widely as a way to easily increase solar capacity on the DC side, irrespective of what equipment is already installed.

Oh, the diagnosis is pretty easy. The key issue in that installation is the installer. 😅

Agreed. I'm not an installer, and for me my installation was mostly a fun DIY project. But my Victron installation looks neater, is certainly safer, and has been working for months now. It doesn't cost much homework to realize that you really do want a GX. As for battery compatibility - as long as the battery can put out 48 V there's no reason for it not to work. I'm using Narada lithiums that can't speak to Victron at all, and it works. The drawback of not having communication is that you have very dodgy SoC readings (Victron think that mine is at 85% when it is fully charged), but that doesn't stop the inverter from inverting.

@Pietvis - sorry for the slow reply, I don't browse the forums that often. The NPFC should have a little pinhole with a reset button behind it. IIRC it is to the right of the RJ45 sockets. It is pretty simple - you press and hold the buttons for a few moments. The status lights will cycle, and then the battery will switch off. Pressing the button again will swith the battery on again. I've found mine to be pretty finicky when connected to a Victron 150/75 MPPT - if there's no solar/inverter input to the MPPT the batteries tends to see the MPPT as a short and go into protection mode. That usually happens if Eskom is down at night. Then I just disconnect the MPPT, and reconnect it later when the sun is up or when Eskom is back.