Author Topic: EEVblog 1385 - 8kW Home Solar Power System EXPANSION  (Read 4282 times)

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Online EEVblog

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EEVblog 1385 - 8kW Home Solar Power System EXPANSION
« on: April 03, 2021, 12:58:09 pm »
Dave explands his 3kW home solar power system to 8kW using new 370W LG NEON 2 panels and Enphase IQ7+ micro inverters!
The complete installation video. Time lapse videos and other analysis videos to come on the EEVblog2 channel.
Thanks to LG Australia, Enphase and Clenergy:
https://www.lg.com/us/business/solar-panels/lg-LG370N2W-G4
https://enphase.com/en-au/products-and-services/microinverters/family
Clenergy racking: https://www.clenergy.com.au/

 
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Offline coppercone2

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Re: EEVblog 1385 - 8kW Home Solar Power System EXPANSION
« Reply #1 on: April 03, 2021, 03:55:35 pm »
Added 1.2 kW recently to a 2.5 kW system. we take it slow

I recommend full machine crimps with the Rennsteig 624 1301 3 RT

I don't like those folded things on the roof.

I also got a type 2 surge protector installed next to the panel

After 1 year our solaredge failed but it got replaced by warranty, probably because the power grid here is on crack

Also, I recommend some high power loads if they start charging you for export, you can have luxuries like hosing your car with the best warm soap and air drying it with a 5kW blower every day
« Last Edit: April 03, 2021, 03:59:54 pm by coppercone2 »
 

Offline tszaboo

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Re: EEVblog 1385 - 8kW Home Solar Power System EXPANSION
« Reply #2 on: April 03, 2021, 11:59:03 pm »
Everyone seems so invested in this microinverters, and I still dont get it. A few years ago we analyzed 7000 installations and the break even time to invest into microinverters was like 2 years longer than regular inverter.
The regular IQ7 is so weak, it cannot handle the average inverters today. The IQ7+ is better, but for a 350W panel, the output is limited to 295VA. The IQ7X can output 320W. And it costs 121 EUR this thing, that's the price of a full (Chinese) panel. And if your roof has shading problems, a solaredge system has those DC optimizers, that cost 45 EUR. Yes they need a separate inverter box, that costs money, but at 8 panels it is already cheaper than the micro inverters.
I can only see the benefit for installers. When the bloody under engineered things blows up, because it is installed on the back of a hot panel, they can just send you the money back, instead of going on site and fixing your installation under warranty.
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Online Brumby

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Re: EEVblog 1385 - 8kW Home Solar Power System EXPANSION
« Reply #3 on: April 04, 2021, 12:20:55 am »
Everyone seems so invested in this microinverters, and I still dont get it.
Start with this: "Single point of failure."

Quote
I can only see the benefit for installers. When the bloody under engineered things blows up
Evidence?  Or is this only conjecture?

Quote
, because it is installed on the back of a hot panel,
Not ideal - but I haven't studied the thermal design.

Quote
they can just send you the money back, instead of going on site and fixing your installation under warranty.
Not in Australia mate!  It'll get fixed - or there will be hell to pay

.... and then it'll get fixed.
 

Online bdunham7

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Re: EEVblog 1385 - 8kW Home Solar Power System EXPANSION
« Reply #4 on: April 04, 2021, 12:54:50 am »
Everyone seems so invested in this microinverters, and I still dont get it.

Safety--no HVDC.  Every solar system fire I've ever heard of--and there have been a few--has been HVDC related.  You would have to work very hard to start a fire with a microinverter system.

Reliability--while earlier Enphase units had issues, they've been reliable for a decade now.  Mine are 8 years old and still working 100% with no failures.  And if one does fail, I lose 1/30 of my capacity.

Efficiency--while you can use SolarEdge equalizers with a regular central inverter, the microinverter does all that in one step.  I lose nothing due to partial shading.  The issue of 'clipping' or 'not being able to handle' a certain size panel is pretty much a non-issue because the amount of time that a panel has enough light to put out 90%+ of its rating is quite small, even here in SoCal.  In northern Europe, it's probably quite rare. 

Ease of installation and cost effectiveness--mine paid for themselves three years ago.  I'm not sure how you are 'analyzing' installations, but here there are real-world permitting and other issues that have to be accounted for when you consider costs.  For example, the 'clipping' issue can actually be a benefit, even though a small amount of energy is lost, because it lowers the size of the wiring and circuitry required.  Just as an example, using the old M215 inverters that I have, I can run 34 panels on a relatively standard electrical system.  Since I have 240 watt panels and could use bigger ones, at some point the system occasionally maxes out and I 'lose' some power.  However, if those inverters harvested ALL of that energy, I would not be allowed to connect 34 panels to my system because the maximum power would exceed a certain calculated metric (80% of 20% of 200 amperes if you want to know...). 

Newer larger panels and inverters will run into the same math issues.  For residential, redoing the base electrical service would be a huge expenditure that would eclipse any minor cost issues with the particular type of solar installation.
A 3.5 digit 4.5 digit 5 digit 5.5 digit 6.5 digit 7.5 digit DMM is good enough for most people.
 
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Offline Kleinstein

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Re: EEVblog 1385 - 8kW Home Solar Power System EXPANSION
« Reply #5 on: April 04, 2021, 07:29:42 am »
Even in not so ideal northern europe, short time the peak insolation  can go a bit over 100% - this happens with some clouds, getting direct sun plus some refleced off clouds.
Depending on the angle one may however never get the sun at the right angle. Dave's old panels would likely never see the full sun because of the orientation.

With now relatively low prices for the panels it makes absolute sense to have the inverter power lower than nominal panel power.  At peak times there is anyway the tendency to have too much PV power in the grid. From the grid side it would probably better to have the inverter only at some 50-70% of the panel power.  They may have to adjust the money they pay for PV sold to the grid - like lower at peak times and maybe higher at night  :-DD.
 

Offline tszaboo

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Re: EEVblog 1385 - 8kW Home Solar Power System EXPANSION
« Reply #6 on: April 04, 2021, 07:31:35 am »
Everyone seems so invested in this microinverters, and I still dont get it.
Start with this: "Single point of failure."

Quote
I can only see the benefit for installers. When the bloody under engineered things blows up
Evidence?  Or is this only conjecture?

Quote
, because it is installed on the back of a hot panel,
Not ideal - but I haven't studied the thermal design.

Quote
they can just send you the money back, instead of going on site and fixing your installation under warranty.
Not in Australia mate!  It'll get fixed - or there will be hell to pay

.... and then it'll get fixed.
Here is the warranty site:
https://enphase.com/en-au/support/labor-reimbursement-warranty-service
You have to judge for yourself, if 125 AUS is enough to drive to your place and 25 AUS is enough to get them to your roof.
If a SMA or Solaredge inverter dies, they come on site and replace the inverter under warranty, they have to.
If that happens after 20 years, well, you were lucky, You still only need to replace 1 inverter. If the same starts happening on your roof.. 20 years from now half your inverters dead. That is a lot more work to get fixed.


Ease of installation and cost effectiveness--mine paid for themselves three years ago.  I'm not sure how you are 'analyzing' installations, but here there are real-world permitting and other issues that have to be accounted for when you consider costs.
The way we "analyzed" the installations, was this: I was working at a company specializing in solar technology data collection. And dealing with so-called green certificates that were a government incentive. We had over a billion data points of 7000 solar installations, several experts, algorithm to detect partial shading, and very good understanding of the underlying costs. I was doing there the monitoring hardware, so not directly involved with the analysis, but the end result was clear.

We also had financial incentive to recommend the best possible system for customers, as when they generate more power, there was more income for the company. And still, we wouldn't recommend microinverters.
For example, the 'clipping' issue can actually be a benefit, even though a small amount of energy is lost, because it lowers the size of the wiring and circuitry required.  Just as an example, using the old M215 inverters that I have, I can run 34 panels on a relatively standard electrical system.  Since I have 240 watt panels and could use bigger ones, at some point the system occasionally maxes out and I 'lose' some power.  However, if those inverters harvested ALL of that energy, I would not be allowed to connect 34 panels to my system because the maximum power would exceed a certain calculated metric (80% of 20% of 200 amperes if you want to know...). 

Reliability--while earlier Enphase units had issues, they've been reliable for a decade now.  Mine are 8 years old and still working 100% with no failures.  And if one does fail, I lose 1/30 of my capacity.
So you are saying that it's better that they output less power due to some local regulation that you have.  :-//
The average panel size is 350W today.
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Offline coppercone2

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Re: EEVblog 1385 - 8kW Home Solar Power System EXPANSION
« Reply #7 on: April 04, 2021, 07:53:27 am »
dave jones do you have surge protection for your system?

if I had that much I would think about a lightning rod even, but I don't really know much about them *until someone frees up those expensive IEC standards*
 

Offline mikeselectricstuff

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Re: EEVblog 1385 - 8kW Home Solar Power System EXPANSION
« Reply #8 on: April 04, 2021, 10:24:48 am »

Also, I recommend some high power loads if they start charging you for export,
Why would you not just disable export if they started charging for it ?
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Online EEVblog

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Re: EEVblog 1385 - 8kW Home Solar Power System EXPANSION
« Reply #9 on: April 04, 2021, 10:28:43 am »
The regular IQ7 is so weak, it cannot handle the average inverters today. The IQ7+ is better, but for a 350W panel, the output is limited to 295VA.

That indeed seems to be the case, very dissapointing.
I've got 370W panels, and I'm wasting 80W per panel, or 1.12kW total.
Although curiously the datasheet says it's designed for modules up to 385W, so  :-//
« Last Edit: April 04, 2021, 10:35:16 am by EEVblog »
 

Online EEVblog

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Re: EEVblog 1385 - 8kW Home Solar Power System EXPANSION
« Reply #10 on: April 04, 2021, 10:33:11 am »
Everyone seems so invested in this microinverters, and I still dont get it.

1) Safety, no HVDC.
2) Redundancy. If one panel or inverter goes down you only lose that one.
3) Shading, dirt, poop etc. You only lose that one panel, it doesn't impact the string.

If you want the cheapest system you wouldn't use microinverters.
 

Online EEVblog

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Re: EEVblog 1385 - 8kW Home Solar Power System EXPANSION
« Reply #11 on: April 04, 2021, 10:36:39 am »

Also, I recommend some high power loads if they start charging you for export,
Why would you not just disable export if they started charging for it ?

At that point you get a battery system.
 

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Re: EEVblog 1385 - 8kW Home Solar Power System EXPANSION
« Reply #12 on: April 04, 2021, 10:37:31 am »
dave jones do you have surge protection for your system?

Nope. Our entire suburb is underground wiring, so lightning surges usually don't make it as far as the house.
 

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Re: EEVblog 1385 - 8kW Home Solar Power System EXPANSION
« Reply #13 on: April 04, 2021, 10:41:22 am »
For those not following on twitter, they goofed up the install of both the new Enphase current clamps and the old Solar Analytics one too  :palm:
The system shows we are drawing power when we aren't home, and that power consumption just so happens to match the solar output of our old 3kW system  :-DD
This day was supposed to have only our two fidges (about 200W as you can see at night) consumption all day.
 

Online Brumby

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Re: EEVblog 1385 - 8kW Home Solar Power System EXPANSION
« Reply #14 on: April 04, 2021, 11:27:23 am »
Quote
they can just send you the money back, instead of going on site and fixing your installation under warranty.
Not in Australia mate!  It'll get fixed - or there will be hell to pay

.... and then it'll get fixed.
Here is the warranty site:
https://enphase.com/en-au/support/labor-reimbursement-warranty-service
You have to judge for yourself, if 125 AUS is enough to drive to your place and 25 AUS is enough to get them to your roof.
:palm:  Did you understand that page?  Did you even READ it?

Labor Reimbursement for Warranty Service
(Effective November 1, 2020)
Australia and New Zealand

The Enphase Energy, Inc. (“Enphase”) Labor Reimbursement Program (“Labor Reimbursement Program”) is designed to help solar-electric installation professionals (“Installers”) that do not have a product purchase (or similar) agreement with Enphase offset a portion of the service/labor costs related to replacing Eligible Products (defined below) that has been installed in a PV solar system located in Australia or New Zealand.

This Labor Reimbursement Program is separate from our standard limited product warranties. If your company has entered into a product purchase or other agreement with Enphase governing the purchase of Enphase products, this Program does not apply to you; please refer to the terms and conditions of such agreement with Enphase.
« Last Edit: April 04, 2021, 11:29:02 am by Brumby »
 

Offline ssander

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Re: EEVblog 1385 - 8kW Home Solar Power System EXPANSION
« Reply #15 on: April 04, 2021, 11:41:33 am »
Dave, Thank you for the video. Looks like the microinverters might be the ones to use if I get panels above my place.

Any system would need to maximise the output with what little space I have available as none of my roof surfaces face North.

 

Online bdunham7

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Re: EEVblog 1385 - 8kW Home Solar Power System EXPANSION
« Reply #16 on: April 04, 2021, 02:14:33 pm »
So you are saying that it's better that they output less power due to some local regulation that you have.  :-//
The average panel size is 350W today.

If 'local' means the United States, then yes.  And the panel size issue just scales, the concept is the same.  But even if there were no such issue, the loss of energy due to the panel max being more than the microinverter max is a very small issue.  If your inverter can only put out 90% of the panel max, you don't lose 10% of your production, it's more like 0.01%.  But if you analyzed 7000 systems, you ought to know that....
A 3.5 digit 4.5 digit 5 digit 5.5 digit 6.5 digit 7.5 digit DMM is good enough for most people.
 

Online bdunham7

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Re: EEVblog 1385 - 8kW Home Solar Power System EXPANSION
« Reply #17 on: April 04, 2021, 02:32:57 pm »
That indeed seems to be the case, very dissapointing.
I've got 370W panels, and I'm wasting 80W per panel, or 1.12kW total.
Although curiously the datasheet says it's designed for modules up to 385W, so  :-//

There's no reason to be disappointed! This is perfectly sensible system optimization.  Both the inverters and the panels cost money, so why do we assume that the inverters need to be sized so as to use every last erg of energy from the panels and that anything less is 'waste'?  Wouldn't a smaller panel be 'wasting' the inverter's capacity most of the time? 

It's true that your system has a 20% mismatch while mine has about a 7%, but at 7% and a nearly ideal fixed SoCal installation, clipping is extremely rare--some years it never happens.  To get that 370 watts from your panels you need a day when the sun is nearly aligned perfectly (which can only happen 3-4 weeks per year), a perfectly clear day and the panels need to be....cold.  Since Enphase has per-panel monitoring, you can just review your power production graphs in Enlighten and you'll be able to see whenever the power production maxes out or 'clips'.  Figure out how much time each panel is clipped and assume that you are losing 40W per panel (which is likely an over-estimation) and see what you think.

I just did a quick check on mine as we are in that 3-4 week window where the sun is aligned with the panels.  80% for me would be 192 watts per panel.  Some of my panels are occasionally reaching that in the middle of the day, the highest one in the past 7 days was 196 watts, that panel stayed above 192 watts for about an hour.  A system that clipped at 80% would have cost me maybe 4 watt hours in a week on a panel that produced 8.08kWh in that same period.
« Last Edit: April 04, 2021, 02:49:26 pm by bdunham7 »
A 3.5 digit 4.5 digit 5 digit 5.5 digit 6.5 digit 7.5 digit DMM is good enough for most people.
 

Offline coppercone2

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Re: EEVblog 1385 - 8kW Home Solar Power System EXPANSION
« Reply #18 on: April 04, 2021, 03:39:40 pm »

Also, I recommend some high power loads if they start charging you for export,
Why would you not just disable export if they started charging for it ?

so there are plumes of expensive wasteful steam every afternoon

it might be impossible in australia though
 

Offline David Hess

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Re: EEVblog 1385 - 8kW Home Solar Power System EXPANSION
« Reply #19 on: April 04, 2021, 04:01:56 pm »
Regarding replacing copper with silver during World War 2 in the US, the power houses at the dams along the Columbia river also did that, and I assume it was done at other dams.  The copper bus bars were replaced with silver ones and armed guards were posted.
 

Offline tszaboo

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Re: EEVblog 1385 - 8kW Home Solar Power System EXPANSION
« Reply #20 on: April 04, 2021, 07:03:39 pm »
:palm:  Did you understand that page?  Did you even READ it?
Not really, I have better things to do with my time, than figuring out what the warranty is somewhere else.

Everyone seems so invested in this microinverters, and I still dont get it.

1) Safety, no HVDC.
2) Redundancy. If one panel or inverter goes down you only lose that one.
3) Shading, dirt, poop etc. You only lose that one panel, it doesn't impact the string.

If you want the cheapest system you wouldn't use microinverters.
I'm familiar with the claimed benefits.
1) Solaredge and other DC optimizer,  have some communication that limits the voltage on a string in case a failure. So if a wire is broken for example, you have like 5V and minimal current through it. According to the new regulations, you dont even have to install DC isolators. This is only a benefit compared to regular string inverters.
2) I just dont see how this is relevant. I have a freezer at home, if it breaks, I loose maybe 2-300 EUR worth of food 10 hours later. Yet I dont have several small freezers at home. If an inverter breaks, I stop generating power, until the installer fixes it. Several heating systems. I have 1 mains power line coming from the street, what if that one breaks?
The microinverters have shared AC line. This redundance feels like marketing, and if you take one step backwards it doesnt really make sense.
3) Just like with DC optimizers. With half cut cells, they even reduce the panel area that gets effected by shading. I've read that they actually want to go to quarter cut cells in the future, that will reduce the benefits of microinvertes even more.

And this effect is over estimated. We had this nifty algorithm, that could tell a customer, when they had shading over their panels. It was comparing the generation of an installation against neighboring installations, and we sent an email when we found shading. And the average loss was something like 25 EUR a year ( as I remember, you know how memory is).

It was a much larger issue, that inverters shut down when there was too much generation. You have a street, with a transformer feeding it at one end. The AC line and the transformer was designed to convert from the 10KV to 235V. At the end of the street you have 225V due to the voltage drops. They install the system 30 years ago, nobody had solar.
In the meantime, Belgium became one of the most dense in solar installations, but the transformers are the same. So there is still 235 at the beginning of the street, but in the middle you have 240V and the inverters at the end of the street have to shut down, because the voltage is too high. Some people were loosing out as much as 150 EUR/year, because of this, and they cannot do anything about it. DSO doesn't care, because they have no financial incentive to spend money on the lines or the transformer.
They also
4) Cost more
5) Place electrolytic capacitors in heated areas. Regular inverters can be placed in the shade, or have a heatsink built in. Some of them even had fans.

That indeed seems to be the case, very dissapointing.
I've got 370W panels, and I'm wasting 80W per panel, or 1.12kW total.
Thats one of the issues that I'm seeing. Regular strings usually also have DC over provisioning. But that's 20% per panel, very different than 20% of an entire system.
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Offline Dread

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Re: EEVblog 1385 - 8kW Home Solar Power System EXPANSION
« Reply #21 on: April 04, 2021, 07:15:35 pm »
I am in the process of ordering a 6KWh - 8Kw system for use abroad.
The country uses 115V/230V 50Hz and the solar guys I have been in contact with in Miami have suggested everything from Schneider to OutBack Radians to SMA.  Those same Panels that Dave got the LG360N1C-N5 along with a comparable Panasonic panel have been mentioned.

One thing that all three of the companies suggest I stayed away from was MicroInverters.  The reasoning was always the same, they said that the Inverter was the most likely part to burn out and it's better to deal with a single Inverter than 20 of them. They also said they get extremely hot and therefore have a short lifespan. I mentioned shading and one guy replied that the panels would be set in three per series and that should eliminate most of the problems but if they still encounter a problem they would use Optimizes on the affected panels.    I don't know enough about solar equipment to comment but when three different companies stare you away from something it's a done deal in my head.

They all agreed that the SMA system was the most reliable and also said the easiest to service as the new model has two sections, you can remove the Inverter section and leave the lower half with all the wiring in place.  Easiest to service and best warranty at 10 years plus optional 10 extra years for $400+

The wiring proposed was very strange to me.
 Since not much power will be used between 10am and 5pm which is the peak production hours I told them storage was a must.  The LG RES Battery pack was recommended but things got tricky with how to use the power at night.  The last wiring scenario I was told involved feeding a Sunny Boy 230V 50Hz model directly into a Sunny Island 230V unit and then Grid Tie the Sunny Island using an Autoinverter Transformer to split the 230V into two 115V lines. The system creates a Micro Grid during a power Outage and disconnects the mains so that the in the Daytime the Solar panels are still operating.
On a normal night with power the Sunny Island powers the house in Grid Tie mode. (This is the part that confuses me but he mentioned it can be done).  Daves video was great to watch and convinced me that the SMA products are the way to go.  You cannot complain when an Inverter gives you eight years of great service.

Any feedback or questions I should be asking these guys would be greatly appreciated.
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Offline HattedSquirrel

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Re: EEVblog 1385 - 8kW Home Solar Power System EXPANSION
« Reply #22 on: April 04, 2021, 07:22:20 pm »
Why does Dave keep calling it a 5 kW system if it can technically only supply 290 VA * 14 = 4060 VA max? What am I missing here?

Are the panels just called "370 W", but will never reach more than 290 W in any realistic scenario or what is the reason? I find it quite confusing I must say... especially if the system as a whole is labeled with a power rating that is technically impossible to achieve. Wouldn't that be as if I claimed my car could do 400km/h - with a different engine, enough fuel is in the tank, at least for 5minutes.
 

Online bdunham7

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Re: EEVblog 1385 - 8kW Home Solar Power System EXPANSION
« Reply #23 on: April 04, 2021, 07:40:02 pm »
1) Solaredge and other DC optimizer

If we are comparing a Solaredge optimized system with an Enphase system I'd agree the performance seems similar, but so are the costs.  Those optimizers aren't free.  And I'm not sure how well that voltage protection works in the case of a high-resistance but not open connector--or worn insulation that could pose a shock hazard in some cases.  I'm not sure they totally mitigate the HVDC issue.  I know micros do.

And as far as redundancy/reliability issues go, there's a plenty of experience to rely on.  You can talk of heated capacitors all you like, but DC-string inverters have typically had a disturbingly high failure rate compared to even old micros.  Read the warranty terms of each if you want to know the manufacturers take on that. And with DC optimization, the optimizer is in same place as the micro, so where's your advantage?

Quote
Thats one of the issues that I'm seeing. Regular strings usually also have DC over provisioning. But that's 20% per panel, very different than 20% of an entire system.

Why is it very different and when does it matter?
A 3.5 digit 4.5 digit 5 digit 5.5 digit 6.5 digit 7.5 digit DMM is good enough for most people.
 

Online bdunham7

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Re: EEVblog 1385 - 8kW Home Solar Power System EXPANSION
« Reply #24 on: April 04, 2021, 07:50:15 pm »
Why does Dave keep calling it a 5 kW system if it can technically only supply 290 VA * 14 = 4060 VA max? What am I missing here?

It is misleading, but solar systems are often referred to (and sold) in terms of the sum of the panel maximum ratings, which are measured at 1kW/m2 and 25C panel temperature, which rarely ever happens and never for long.  There are other rating schemes, such as NOCT, that would be more appropriate for determining how much power to expect, and how big of an inverter to use.

https://amsolar.com/diy-rv-solar-instructions/edpanelratings

If you look at the datasheet of the solar panels Dave got, you'll see that their NOCT PMAX rating is 273 watts.
A 3.5 digit 4.5 digit 5 digit 5.5 digit 6.5 digit 7.5 digit DMM is good enough for most people.
 
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