Combining MicroInverters and String Inverters - Page 1
Forum section: electronics / general

author: fastbike
author_rank: Regular Contributor
timestamp: November 02, 2024, 04:43:20 am
content: So long story short: we are commissioning the house with 27 panels on a 3 phase Solis 10kW inverter. The standalone garage is getting 14 panels which will have micro inverters due to some shading issues (rails installed today, Enphase gear ordered).The garage and the house share a common meter for the connection from the street, but each is treated as a separate installation with its own distribution board with independent MEN connections.We are using 3 phase Iammeter energy meters to measure the power drawn/exported to the grid, and a separate meter on the output of the house inverter.The Enphase gear comes with some type of gateway device (I've not read enough about it yet to know exactly what it does). Will I need another Iammeter energy meter to measure what it is supplying and then use OpenHAB or similar to control daytime loads i.e. integrate the output of the two solar installations ?Has anybody got a similar setup I can study ?

author: Siwastaja
author_rank: Super Contributor
timestamp: November 02, 2024, 03:48:19 pm
content: You are planning using some kind of optimization device or DIY setup increasing your self-use? Then best would be to let it know total power flow (same which goes through the single meter from the street). Which you can do by adding measurement on common part of circuit, or by measuring the two branches and summing them somewhere. Read the documentation of whatever optimization product you are going to use if they support this kind of summing of branches.Or, you can just optimize based on the house measurement and let the garage PV system live its own life. Maybe that is good enough.It seems to me project like OpenHAB or HomeAssistant and similar are pretty good in integrating data of gazillion of devices together but they lack the big picture about doing automated control (energy or cost optimization). Expect some DIY.

author: fastbike
author_rank: Regular Contributor
timestamp: November 06, 2024, 01:42:18 am
content: I've had two quotes back for the Enphase gear (can't find a local supplier for Hoymiles).It's quite spendy: NZD$200 per inverter, plus another $30 for the cable per panel. And the Envoy is around $500. Another $140 for the disconnect relay. And then the mandatory box plus the breakers to put it all into.Would a 5kW 2 MMPT 3 phase inverter be cheaper - I think so. Would it handle the weird shading patterns that I can observe on that roof - don't think so.So I'm about to pull the trigger. I hoping the Envoy has a local API that I can query for power production.

author: Siwastaja
author_rank: Super Contributor
timestamp: November 06, 2024, 08:15:00 am
content: Usually it turns out that if the place is shady enough for a microinverter solution to producesignificantlymore than a string inverter, then it still produces absolutely so little (due to all that shading) that investing in the more expensive system never pays for itself. I would primarily avoid installing PV in mediocre or poor places, because there is no lack of good places (if you look at the big picture).But of course, there can be other type of motivation than just money. If you want to maximize the amountyouare producing, then you are limited by the install locations you have, and maximizing production with microinverters could be emotionally the right thing to do.String inverter does not care about the "weirdness" of the shading pattern. But if the minimum MPPT voltage is say equivalent of 6 panels (quite usual rating) and you have 10 panels out of which 5 are seriously shaded (so only 5 produce), then it falls below the minimum voltage and goes close to zero while microinverters would still produce 50%. But if this happens "all the time" then the question indeed is how much you are paying to be able to produce 50% of rated power. Like, you pay 30% premium to produce only 50% of an "optimal" system. Given long payback times of any PV install it makes no sense.On the other hand, continuing with the same example, if you shade 3 panels out of 10 then string inverter and microinverter produce roughly the same: string inverter produces a tad below 70% of total rated; microinverter is able to getsomepower out of those shaded panels (but not much because, doh, they are shaded) so maybe it produces 75-80% of total rated during that condition, but loses that extra power, if not more, in generally 1-2%-point lower efficiency and usually higher idle power draw, which affect the system all the time.TLDR:* Partial shading of 20-30% of the roof for hour or two per day or so: just get a string inverter and verify you exceed minimum voltage most of the time* Significantly more shading than that: don't install PV at all* If you are desperate to get some power out of such crappy location, then microinverters or optimizers.

author: nctnico
author_rank: Super Contributor
timestamp: November 06, 2024, 11:42:39 am
content: I'd be careful with string inverters and shaded panels. From a quick scan I did recently, it turns out only the more expensive string inverters can deal with shaded panels. If there is no mention a string inverter can deal with shading in the manual / datasheet, then assume it won't deal with shading at all. Using optimisers which deal with individually shaded panels (for example due to a chimney, pipe, etc) could be a more economic solution.

author: Siwastaja
author_rank: Super Contributor
timestamp: November 06, 2024, 11:52:23 am
content: Quote from: nctnico on November 06, 2024, 11:42:39 amIf true, it would be an alarming defect. My ages old Stecagrid seems to do fine, for example. Every cheap brand at least theoretically have proper wide MPP scan to avoid getting stuck in local minima, but of course there can be bugs and poor implementations. Still, it's 2024 now, not 2014, this is such fundamental basic feature that I would say "extraordinary claims require extraordinary evidence". So it would be interesting to see what sources you found for your "quick scan" and if the claims are credible.I'm not saying you are necessarily 100% wrong, just that if you are right then the situation is pretty bad and worse than I think it is.BTW, I think that if a string inverter gets seriously stuck in local minima even when minimum MPPT voltage is clearly satisfied that is enough reason for demanding a repair or replacement with an inverter which works in the expected way. People should not accept crap like that.

author: nctnico
author_rank: Super Contributor
timestamp: November 06, 2024, 11:58:30 am
content: Growatt is a pretty popular brand and it won't deal with shading at all. The supplier confirmed that. As I added above: If there is no mention a string inverter can deal with shading in the manual / datasheet, then assume it won't deal with shading at all. This could be a patent related issue BTW where the inventor wants crazy money to implement searching for a better optimum.

author: Siwastaja
author_rank: Super Contributor
timestamp: November 06, 2024, 12:20:53 pm
content: Maybe you are right that Chinese are still behind in this. Western inverters have had this since forever and I have assumed Chinese would have implemented it too being such fundamental feature and these inverters otherwise being quite mature already.Goodwe (another cheap Chinese brand) is at least discussing about it:https://community.goodwe.com/solution/How%20does%20Shadow%20Scan%20Work?But even they say it's OFF by default and needs to be enabled (so in practice remains disabled because no one reads the manual).Solinteg, a Chinese brand which I have never heard about talks about it, too. Maybe it's their strong point.Googlingsays that Solis S6 series should have a decent scan and people are happy with the results.My system (Stecagrid) has been working as expected. I had partial shading (4 out of 10) with string going below minimum MPPT voltage which obviously killed the performance. After adding four new panels in series, in unshaded area, the problem basically went away: 10 of 14 panels are producing fully and the four shaded panels bypassing. Been monitoring it since installing the new panels with no surprises, the global scan clearly works and does not get stuck in another local maximum at higher string voltage.

author: tszaboo
author_rank: Super Contributor
timestamp: November 06, 2024, 12:23:47 pm
content: I wouldn't do that. I would either get Solaredge inverters with optimizers on every panel. Or use your selected inverters and place Tigo optimizers on the shaded panels. I have solaredge at home. It's good. Not affiliated. Enphase is just really bad value.

author: nctnico
author_rank: Super Contributor
timestamp: November 06, 2024, 02:06:54 pm
content: Putting an optimiser on every panel gets expensive quickly. The price difference between cheap and more expensive inverters can be hundreds of euros. It takes careful analysis to determine whether having a more expensive inverter is actually worth the money. In the end you want to have a solar panel installation to pay for itself.

author: tszaboo
author_rank: Super Contributor
timestamp: November 06, 2024, 02:25:33 pm
content: Quote from: nctnico on November 06, 2024, 02:06:54 pmThe Tigo inverters are like 40 EUR, so 14 of them is like 560 EUR, which is probably 5% of the total system cost for such a big installation. Solaredge inverters are also a lot cheaper than comparable Fronius, SMA or ABB inverters, and a lot cheaper than anything from Enphase. Of course Chinese inverters are going to be cheaper, but I don't think it will be worth it down the line.Plus, this is not just about the ROI, there are other considerations.

author: Siwastaja
author_rank: Super Contributor
timestamp: November 06, 2024, 03:07:26 pm
content: Quote from: tszaboo on November 06, 2024, 02:25:33 pmOf course anything is a lot cheaper compared to three most expensive "Western" brands. It seems to me everybody really installs Chinese inverters because they give good price - quality ratio, though. You should be comparing to those.If the online claims about Solis handling MPPT "shadow scan" much better than others, that places Solis into pretty good position because it's not expensive. My biggest complaint about Solis is that external MODBUS RS485 port shares the same interface with the datalogger so you can only have either one, not both. For some companies this is a showstopper for our control box, for others they are fine accessing data through our service only instead of Chinese cloud.

author: nctnico
author_rank: Super Contributor
timestamp: November 06, 2024, 03:31:08 pm
content: Quote from: tszaboo on November 06, 2024, 02:25:33 pmAssuming you mean 14 optimisers on all 14 panels then paying 11k euro for such an install (around 5500Wp) is way too much anyway. There is no ROI to be had -ever-. I paid 3800 euro for my 4500Wp install. That over 2 times cheaper and I'm looking at an ROI between 4 to 5 years already. And I consider myself 'lucky' I had a good year in 2023 due to the high electricity prices.

author: Siwastaja
author_rank: Super Contributor
timestamp: November 06, 2024, 03:40:00 pm
content: Quote from: nctnico on November 06, 2024, 03:31:08 pmWhich is about right. Or maybe a bit more can be accepted, but definitely not 2x or 3x.PV needs to be bought at correct timing, especially turn-key. There is this cycle of mass psychosis, rise of prices, demise of market, bankruptcy wave of install companies, dropping of prices to sane levels due to healthy competition, and then the cycle repeats. Here a "normal size" system cost for full turn-key install varies between 6000 - 15000 EUR depending on the timing / psychosis level. What is "normal size" increases as time goes by. And always some people are getting too large systems (e.g. 8-10 kWp). Well in some rare cases that size is a good idea but that needs design of the whole, not just slapping a 10kWp inverter and 25 panels on the roof.With too large systems, self-use% becomes a problem. In some countries there are indirect or direct subsidies where you get paid for export at all times but I don't think it leads to right decisions. It makes no sense trying to absolutely maximize production. PV is best distributed and mostly self-used. This also prevents any last-mile voltage rise problems you can see happening in countries which subsidize export price and people get 10kWp systems.

author: tszaboo
author_rank: Super Contributor
timestamp: November 06, 2024, 04:00:35 pm
content: Quote from: nctnico on November 06, 2024, 03:31:08 pmOP wants a system with 27+14 panels, and ~15KW peak capacity. I think including installation 10K is a reasonable price.My 4KW system was also ~4K, including installation costs, including the optimizers, and has about paid for itself already.

author: fastbike
author_rank: Regular Contributor
timestamp: November 06, 2024, 11:46:09 pm
content: Quote from: tszaboo on November 06, 2024, 04:00:35 pmWe've done the original system with 27 panels and a 4 MPPT input Solis inverter. There is no shading on this part of the system (2 story house, roof facing almost due north) but we ran out of room to use the remaining panels from the pallet.From analysis and observations of the second roof on the site (garage) we figured we could get up to 18 panels installed but 14 was much easier as the additional 4 required some funky rails due to roof purlin spacing etc. So 14 it is !I have had 3 local quotes for the Enphase gear (equipment only) and the price differences are +50% between the official dealer (cheapest) and the others. My installer is happy for me to do the physical install, as long as I take a photo of each panel/inverter. He will do the inspection and installation/connection of the switch gear.The cost delta between the Enphase and a good quality 5kW 3 phase inverter is not that high when taken as a a percentage of total system cost. So Enphase it is at this stage.One other question - last night I did the basic Enphase online training and got my certificate. Most of the questions / info was reasonably straight forward.One thing I picked up was with the 3 phase IQ cables they have three variants with different spacing between the plugs: 1.3, 2.0 and 2.3 metres. The first is for portrait and the other two are for landscape. However they say for portrait panels 1100mm and wider you should pick the 2.0m cable. My panels are 1134 - with an 18mm clamp between - so on 1152mm spacing.Should I order the 2.0m (more expensive cable) ?

author: nctnico
author_rank: Super Contributor
timestamp: November 06, 2024, 11:55:07 pm
content: I'd be careful rating expenses as a small percentage of total system cost. It is easy to fool yourself that way. Better calculate ROI. Especially when those 14 panels are not in an ideal location.It is like saying a 5k bathroom sink is peanuts compared to buying a 300k home but it still is a 5k bathroom sink (with a 30 years mortgage payment + interest)!

author: fastbike
author_rank: Regular Contributor
timestamp: November 07, 2024, 01:54:44 am
content: Quote from: nctnico on November 06, 2024, 11:55:07 pmThe main system has a cash payback of 5 years. The additional one will be around six years. With interest rates currently low (I can finance for 3 years at 1%) I'm happy to use a cash payback rather than a discounted cashflow approach.

author: Siwastaja
author_rank: Super Contributor
timestamp: November 07, 2024, 06:45:33 am
content: Quote from: fastbike on November 07, 2024, 01:54:44 amHow did you calculate it? For a partially shaded microinverter system paybacks are usually in range of 20-100 years, that is why I'm suspecting you have miscalculated.5 years for the main system sounds plausible.How is the pricing model for exporting excess to grid where you live? This is pretty fundamental question for large PV systems. Usually it's significantly worse than import price (for good reasons) therefore marginal cost for a larger systems gets worse and worse.

author: nctnico
author_rank: Super Contributor
timestamp: November 07, 2024, 10:52:11 am
content: FYI: I based my decission to get/install solar panels on having a worst case ROI of 5 years and a lifespan of 10 years. Initially I projected and ROI of less than 3 years but electricity prices dropped faster than expected and now there is a feed-in tariff as well which set the ROI back to nearly 5 years. It is impossible to foresee what is going to happen where it comes to energy / electricity distribution & pricing beyond 10 years. This is also why I choose to get the cheapest inverter. It will probably last 10 years. When it breaks there are likely better inverters or it may even be possible new regulations or home storage systems make it necessary / worthwhile to replace the inverter long before the panels are end-of-life. And it is also possible it makes no sense to replace the inverter at all.

author: Siwastaja
author_rank: Super Contributor
timestamp: November 07, 2024, 10:59:21 am
content: Quote from: nctnico on November 07, 2024, 10:52:11 amThis is good thinking, and usually cheapest per kW panels should be used. It is specifically stupid to invest more money into "premium" panels with salesmen pitching about "longer lifetime" (without giving any concrete extra warranty compared to cheaper ones) or "local manufacturing" (when they really all come from China anyway) or "much better efficiency and these produce even under snow" type bullshit.

author: tszaboo
author_rank: Super Contributor
timestamp: November 07, 2024, 01:02:13 pm
content: Quote from: fastbike on November 06, 2024, 11:46:09 pmMy bad, I seem to have misunderstood. In any case good luck with your system.I just dislike Enphase passionately, because IMHO it's a worse system for more money with more drawbacks, clipping, extra boxes for the data and disconnection, and subscription. But it's a free market.

author: Geoff-AU
author_rank: Frequent Contributor
timestamp: November 07, 2024, 10:37:31 pm
content: I spend more money than necessary in other areas of life and derive pleasure from the extra expense so if people want to pay too much for DC optimisers or microinverters and feel good about it then so be it.I bought good quality string inverters with global MPPT scan and they just chug out power day after day, reliably and efficiently.

author: Siwastaja
author_rank: Super Contributor
timestamp: November 08, 2024, 08:52:24 am
content: Quote from: Geoff-AU on November 07, 2024, 10:37:31 pmOf course but people should have access to the information and know what they are doing. Pay premium for premium features that actually do what is promised. We (as a player on the smart energy business) have seen aggressive microinverter sales companies who sell FUD (false claims about others) and false promises of their own systems.I would like to see microinverter systems evolve and gain real traction on the market through real advantages but currently it seems they are falling behind in the competition, i.e. quality is goingdown(e.g., they have no resources to update their product lines for new higher-power panels -> hence they clip power, totally unacceptable!), while competion is going forward (string inverters having more and more MPPT inputs, smaller start/minimum voltages, battery option for very little extra cost, better efficiency...I hate to see it when the underdogs don't get their shit together but instead start to play dirty. FUD and lying in marketing are reasonsaloneI will not recommend microinverters to anyone. If a fresh new player who does something new on the field pops up I'm super happy to change my mind.

author: tszaboo
author_rank: Super Contributor
timestamp: November 08, 2024, 09:18:34 am
content: Quote from: Geoff-AU on November 07, 2024, 10:37:31 pmI understand why people would spend more money on something rather than absolutely necessary. In the end, the system I bought is more expensive than some chinese inverter and panels making some power. Which made the ROI like what, half a year longer? But then,Meanwhile I have data per panel, higher efficiency, open modbus protocol on the inverter to read out data even if the cloud thingy gets shut down, and global 10% DC overprovisioning in the system instead of like 30% per panel, like you do with an Enphase. I just don't get why people spend more on a worse system. Probably marketing, and installers getting a kickback for offering it.Like their battery offering, which was a bunch of microinverters slapped on a battery pack. Does one really need to explain why that's a bad idea?

author: Siwastaja
author_rank: Super Contributor
timestamp: November 08, 2024, 09:47:05 am
content: Quote from: tszaboo on November 08, 2024, 09:18:34 amTo be fair, this seems to be standard feature on every random Chinese inverter these days. Sometimes with a bit of trouble finding the correct document with Google - e.g. Sofarsolar has at leastthreedifferent interface specifications with no documentation to which model numbers they apply -, but you can always do it.

author: nctnico
author_rank: Super Contributor
timestamp: November 08, 2024, 10:42:24 am
content: Quote from: Siwastaja on November 08, 2024, 08:52:24 amI don't see microinverters ever becoming a viable option from a financial standpoint. Having a single unit (=string inverter) doing the job of 20 seperate units is always going to be cheaper due to manufacturing, maintenance and handling costs alone.From what I've read from Enphase, getting a system running requires a lot of fiddling with software, registering online, etc, etc. They should drop all that crap and make their system work out of the box. Plug & play. That alone would save a lot on installation and maintenance costs. Nobody cares about monitoring.

author: Siwastaja
author_rank: Super Contributor
timestamp: November 08, 2024, 12:16:26 pm
content: Quote from: nctnico on November 08, 2024, 10:42:24 amI believe it could be possible but it requires a different mindset. I.e., they should besolvingproblems, not adding them. They concentrate on a few made-up/exaggerated problems and forget all the rest.But there is room for improvements. E.g. DC cabling between panel and inverter. DC connector mess with MC4 and compatibles.Microinverters do not even try to do aynthing about this. You still wire the panels to the inverters. Shorter wires, yes. Still wires. Still connectors. Still authorities saying you must match the connector brands. How the fuck you are supposed to do that, buy Enphase branded MC4 connectors, strip off the existing connectors from panel stubs and re-crimp the Enphase MC4 connectors? At least on a string inverter you have much fewer connectors to crimp.No,microinverters would need to integrate into the panel itself, to create an AC panel. Then it needs a well designed weather sealed AC plug system. Just like MC4, but single plug for L,N,PE. Then add a reliable and problem-free power line communication or wireless system. Engineer it all top-notch reliability, but also engineer it for low cost (increasing NRE to decrease unit cost), and then apply economy of scales to bring the final product price down. Which is chicken-and-egg, you need money upfront for all that work.And do all of the above really well, there is not much room for error because competition from normal string inverters is harsh, and optimizers cater pretty well for those who want to improve trackability of panels + partial shaded production.

author: nctnico
author_rank: Super Contributor
timestamp: November 08, 2024, 02:52:46 pm
content: That sounds like integrated solar panels to meIt could be worthwhile but the major problem is that it will take time for the technology to mature and builders & architects to embrace this technology. IMHO even the retrofitted solar panels aren't mature technology at this point. The whole issue with non-compatible MC4 connectors blew my mind. I also think the panels are too big too handle safely and make a system harder to install than it should be. Needing to bolt the panels down is also not convenient. Especially when you need to take a single panel out. Some kind of click / lock system would be much better for maintenance but it would have to be an industry standard.

author: tszaboo
author_rank: Super Contributor
timestamp: November 08, 2024, 06:36:08 pm
content: Quote from: nctnico on November 08, 2024, 02:52:46 pmIf you had a professional installer, two guys can place an entire installation in like 3 hours.Its really not big of a deal.

author: nctnico
author_rank: Super Contributor
timestamp: November 08, 2024, 06:39:29 pm
content: Quote from: tszaboo on November 08, 2024, 06:36:08 pmHave you ever seen those 'professional' installers use any kind of safety gear? Most (if not all) don't because handling a big panel while being strapped in a safety harness doesn't go together so well. And wait until the wind picks up... I'm very sure professional installers would like smaller panels instead of larger. Keep in mind roof tiles are typically about 35x35cm; that is not some random coincidence. If it where more practical to make these larger, they would have been larger.

author: Siwastaja
author_rank: Super Contributor
timestamp: November 08, 2024, 06:48:26 pm
content: Quote from: tszaboo on November 08, 2024, 06:36:08 pmThis is true, that's why I'm saying current situation is good enough so that competing against it will be tough.Current systems are not ideal from reasons nctnico points out but popularity and competition has wed out inefficient install companies and forced those who want to remain in the market to invent efficient processes and deal with the details. Professionals can do two domestic install sites per day, so 10 install a week. Maybe installs could be made 5% faster and 50% simpler to learn but simplicity does not matter to professionals who do this and only this every day, and 5% faster is still the same 10 installs a week.

author: nctnico
author_rank: Super Contributor
timestamp: November 08, 2024, 07:06:59 pm
content: Quote from: Siwastaja on November 08, 2024, 06:48:26 pmNo. You are overlooking that the majority of the installers who do 10 installs a week do not adhere to work safety regulations at all. If you want to see acrobats without a safety net, go watch solar panel installers. Evel Knievel wouldn't do such crap if he where still alive. Needless to say this is not viable a long term situation either through fines or Darwin awards. The proper installers either use safety harnesses or use scaffolding (which is more convenient). But they won't be doing 2 installs are day because dealing with the scaffolding alone takes a couple of hours by itself. IOW: if you want to make a more competitive solar panel solution, a good long term strategy is to create a system which is also safer to install.

author: Siwastaja
author_rank: Super Contributor
timestamp: November 08, 2024, 07:17:48 pm
content: Quote from: nctnico on November 08, 2024, 07:06:59 pmI would want to agree with you, but it seems the current system is working, from the fact this has been going on for years and years. So it's probably more sustainable than you think. Just like it's a compromise on every other respect, it's also a compromise on worker safety. Clearly laws and regulations are ignored. Yet surprisingly few people actually die doing that. Go figure.

author: nctnico
author_rank: Super Contributor
timestamp: November 08, 2024, 07:26:39 pm
content: True, but it leaves room for a manufacturer to create a demand for safer to install solar panels by swaying public opinion. In the NL the government is actively going after solar panel installers who work unsafe BTW as there are several lethal accidents each year and many more accidents with serious injuries. IMHO just leaving the situation as-is because only a few people die (or get seriously injured) is NOT acceptable. Especially if it is just to make a few bucks extra.

author: Siwastaja
author_rank: Super Contributor
timestamp: November 08, 2024, 07:48:13 pm
content: Well, that's also one reason why I believe alternatives will have a chance. But they need to hit the nail in many respects simultaneously. Not introduce new problems; solve enough of the old. And bootstrap the market from scratch with massive investments so they can be affordable from day one to buy. Not an easy task.Microinverters are crap because they introduce more new problems than they solve:* More DC-to-DC connector interfaces* Having to do both AC and DC connection* Having to mount and wire up 20 inverters instead of 1* Track record of reliability issues due to placement of inverters* Worse production under some conditions, due to* Worse efficiency* Clipping of peak production power because of slow response to the market increasing panel power* Higher idle consumption* Possibly a dangerous product which does not have the mandated grid isolation relays due to cost optimization done in desperation by dying manufacturerWhat problems do they solve?* Increase in production under some other conditions* Per-panel data for troubleshooting* Wiring on the roof is AC instead of DC

author: fastbike
author_rank: Regular Contributor
timestamp: October 10, 2025, 05:25:28 am
content: Quote from: Siwastaja on November 06, 2024, 03:07:26 pmCan you help with some advice on the RS485 port on the Solis. We have a S6-EH3P10K-H-AU inverter. I'm trying to use a Waveshare RS485/Ethernet bridge but cannot get it to respond to requests from Modbus Poll - I just get timeouts even though I can see the ACT light blinking.I've followed the instructions athttps://github.com/alienatedsec/solis-ha-modbus-cloud

author: brucehoult
author_rank: Super Contributor
timestamp: October 10, 2025, 10:31:16 am
content: Quote from: nctnico on November 08, 2024, 06:39:29 pmI got ridiculed online when I was talking about the prices of "200W"(1 m^2) panels."You need to look at 400W panels" I was told.Actually, the best prices in NZ now are for "650W" (3 m^2) panels.I ended up buying 6x 440W panels JAM54D40-440/GB for US$60 + tax each. The shop was trying to push 645W LONGi LR7-72HVH-645M panels but I consider them to be past the size and weight that is comfortable for one person to load / unload / carry. I can deal with the 22kg 2m^2 ones.But for sure 1m^2 would be more convenient if they were price competitive -- they might have a chance of fitting in my station wagon, which even the 2m^2 ones don't.The 2m^2 panels I bought (and I think most of them) would only have about a 1/4" clearance (1/8" each side) between the wheel wells of a Ford Ranger, and only just fit in the longer bed of a single-cab, and not at all in a double-cab version (the most popular).The 645W panels are the same width (1134mm) but 2382 long. That's almost 7'10" for Americans.But anyway, I'm just using my panels on the lawn. They're never going on the roof (at least not at this rented house). They are organised in two strings of three panels, feeding into two 1200W MPPT controllers at around 100V 12A.At this time of year they should be at a 35º angle, but actually with 10% over-paneling (2640W into a 2400W system) just about dead flat is fine. In December a 12º slope will be ideal, but 0º (or 6º with 2 concrete blocks on one side and one on the other) will be basically perfect.Now that I've got to the point of spring that I don't need heating all night I'm effectively about 90% off-grid, as in the past few weeks I've been paying for on average no more than about NZ$0.50/day for electricity on top of the fixed NZ$1+GST ($1.15) daily charge. That's down from $5.44/day in October 2024, $8.86/day in October 2023, $6.74/day in October 2022. It's $1.66/day for the 9 days so far this month and it's actually been pretty rainy and/or overcast most of the time with just 800W-1200W produced most of the time.That NZ$1.66/day is US$0.95, €0.82, £0.72.Once we get into actually good weather that should go to $1.20-$1.30/day (it is already, some days)On the sunny days my 6kWh battery is full again by midday (after getting me from ~6 PM to ~9 AM), and there is a ton of free electricity in the afternoon for aircon, cooking, clothes and dishes washing, etc.

author: Siwastaja
author_rank: Super Contributor
timestamp: October 10, 2025, 03:53:39 pm
content: Quote from: fastbike on October 10, 2025, 05:25:28 amNote that the RS485 pinout is different for every Solis S6 model series, go figure. Try RS485 A = RJ45 pin 5 (blue-white if you use standard Ethernet cable) and RS485 B = pin 4 (blue). Also, always try swapping A and B. Check slave address - 1 by default on Solis I guess, but worth verifying from the inverter settings.These Homeassistant based things get so complicated withdozensof failure points - a massive number of hardware boxes then massive number of software layers - so they are nearly impossible to debug. It's a hobby in itself.

author: Siwastaja
author_rank: Super Contributor
timestamp: October 10, 2025, 03:55:51 pm
content: Quote from: brucehoult on October 10, 2025, 10:31:16 amSo it seems you got the message, and bought the right thingsSo we were right. Sorry if it felt like "ridiculing".

author: tszaboo
author_rank: Super Contributor
timestamp: October 10, 2025, 04:14:05 pm
content: Quote from: brucehoult on October 10, 2025, 10:31:16 amI think you went into a discussion opinionated, with bad information, and you just got some helpful info on how to fix your misconceptions. Are you salty, that you got help?

author: nctnico
author_rank: Super Contributor
timestamp: October 10, 2025, 10:53:40 pm
content: Quote from: brucehoult on October 10, 2025, 10:31:16 amThat is exactly my point. IMHO while these solar panels offer best price / performance, they aren't primarily made to be put on roofs but are made for use in large scale solar farms where they use lifts of even robots to install panels. A bigger panel simply means less installation costs per surface area. During the long planning phase (years!) of my own solar install I noticed that panels got bigger and bigger making the power output look higher but the increase in power output per surface area didn't increase that much. I have 375Wp panels (19kg each) on my roof but per surface area they have the same power output compared to the panels you got.A panel of over 2.3 meters in length and nearly 30kg in weight, would be very hard to handle if you have to mount it on a roof. And their size makes them less flexible to get to an optimum layout on a roof in where it comes to chimneys, dorms and roof windows.Anyway, at least you have the space to put the solar panels in the garden (and didn't have to haul them onto the roof >6m high like I did). Although, in your case I would try to get proper mounts for flat roofs which are weighed down. The way the panels sit now, they are likely to be blown away by the first storm.PS: are those banana trees in the background? If yes, do they produce edible bananas?

author: EEVblog
author_rank: Unknown
timestamp: October 11, 2025, 12:05:56 am
content: Quote from: brucehoult on October 10, 2025, 10:31:16 amLooks like nothing holding them down? That's begging for wind to make them airborne.

author: tszaboo
author_rank: Super Contributor
timestamp: October 11, 2025, 12:56:56 am
content: Quote from: nctnico on October 10, 2025, 10:53:40 pmSome dude grabs it, walks up a ladder, and to installs it.I see you want to over regulate this installation market. I also don't like walking on the roof, but that's OK, because I can pay someone else to do that.

author: brucehoult
author_rank: Super Contributor
timestamp: October 11, 2025, 02:40:03 am
content: Quote from: tszaboo on October 10, 2025, 04:14:05 pmI'm never opinionated about a field I'm just starting to explore! I simply presented the best deals I'd found until that point. All the "power station" manufacturers sell and recommend 200Wish panels, and they are certainly a convenient size. There is no obvious physical reason for them to be a massively worse cost per W than 400W panels -- slightly more, sure, given unit handling and stocking costs, and that they still need connectors and use slightly more framing material per square meter.It still took considerable searching to find a local store with 400W panels for US$60 not $100+. I don't live in Europe or North America. It was at least useful to know that it might be possible. And even then it was am industrial park place 205 km from me staffed entirely by Chinese, most of them with very little English, and offering zero support.They even wired up the MC4 cables I ordered from them incorrectly, with one conductor having male connectors on both ends the other having female connectors on both ends. The MC4 to XT60 cables that came with my equipment had it clearly labelled which was + and which -  but I hadn't noted which. We ended up debating this in the warehouse for 15 minutes. They weren't even able to tell me which connector on the panels was + and which - but it just seemed wrong to wire a cable they way they did -- that would mean it's impossible to plug a panel directly into the solar controller in the field. But never having done this before I couldn't be sure of my facts and could only ask if they were sure. I got home and plugged into one of the panels and measured the voltage and sure enough it came out correct directly attached to a panel but wrong polarity via their cable (and right if I put both cables they sold me in series). I had to cut off their connectors and crimp on new ones. NBD, but you'd think a shop could get it right. To their credit, they gave me four spare MC4 connectors for free, so I didn't have to buy some to correct the problem.In the end it all works perfectly. Yesterday was very overcast and I only got 60% charge into the 6kWh battery by 6 PM. That was down to 5% or so in the morning by the time I cooked breakfast and the sun got high enough. But then today the battery was at 100% by 2 PM (as well as running all the loads), and in the 90 minutes since then I've cooked dinner in the air fryer and now my bed sheets are in the washer, both using electricity that would otherwise not have been taken out of the panels, with the battery staying at 100%. The air fryer uses 1700W, and the clothes washer peaks at 2kW while heating water but only uses 0.55kWh in total in a 1 hour 40º C cycle. Spin drying uses 520W getting up to top speed but only 350W once up to speed, if anyone cares. There is similarly ample afternoon spare power to run the portable air conditioner (1000W).https://www.pecron.com/products/pecron-mc4-to-xt60-cable

author: brucehoult
author_rank: Super Contributor
timestamp: October 11, 2025, 02:59:58 am
content: Quote from: nctnico on October 10, 2025, 10:53:40 pmI've had winds up to 100 km/h in the month they've been sitting there. There's not even the slightest sign of wanting to budge. It's pretty sheltered, surrounded within 5m or 10m of the house on the north side, shed (and banana) on the south, huge bamboo hedge to the west, and citrus trees and feijoa hedge 15m to the east.If a really big storm is coming it's the work of 5 min to move the concrete blocks and put them flat on the grass. Or, I can sling some cord through the holes in the panels and around the concrete blocks ... 12x 12kg = 144kg for three panels, plus the 66kg of the panels themselves. At a 6º angle, with the shed in that direction? Not going to move.I have a design drawn up using professional certified Clenergy components including CLNERTL3060 "30º-60º" adjustable rear legs (which I can make do a near-ideal 20º-50º with a slight geometry change), on a timber frame, with sandbags for ballast. I've done the wind loading calculations for that. But that stuff is going to cost around NZ$1000 -- more than the panels! -- and current experience shows it's absolutely not necessary from spring equinox to autumn equinox (at least), so I'm going to leave that until April or so.In December, 12º is the ideal angle, so my current 6º on the concrete blocks (2 high on one side, 1 high on the other) is closer than 20º would be anyway :-)QuoteAbsolutely! Delicious! The problem is you get 100 all ripe at the same time.

author: brucehoult
author_rank: Super Contributor
timestamp: October 11, 2025, 03:10:03 am
content: Quote from: EEVblog on October 11, 2025, 12:05:56 amAt the moment. They haven't shown any signs of budging in 100 km/h winds (reduced a lot my the nearby shelter) so far. I'm going to tie them down to the concrete blocks before summer storm season. There not a lot of lift possible at that flat angle anyway. It will be a different story when I make up proper adjustable 20º to 50º mounting before winter. There will be sand bags involved. I've already calculated how many.