microinverter or hybrid inverter?

UnhappyCustomer

My plan is to install solar PV with a hybrid inverter with the idea of putting batteries in the future (if needed) however, I think I would need the microinverters as well because my area is full of trees and shade could be a problem.

I've been told by one provider that I can either install the panels with the hybrid inverter or the enphase with the microinverters.

Is this true? What would you go for?

bullit_dodger

Shading is complex. Depends a lot on the actual shading in place. For example while you might have shading, perhaps its only from dec-> jan in which case you might be missing very little anyway.

So you can install optimizers on all the effected panels which experience shading and then use a String inverter. You don't -HAVE- to use micro-inverters. That said, micro-inverters are a good solution too and depending on the size of your installation could be a more cost effective solution. Typically if your are 5-6 panels or less Micro-inverters are the way to go from a cost perspective, over that then string inverters + optmizers are better. It's not a hard rule though, the answer (fiscally) depends on a lot of factors.

Have a read up (watch) on Youtube.

(447) Solar Panel Shading (Part 1): Are Optimisers and Micro inverters Worth It? - YouTube

Don't just watch one.....get a good feeling from watching a few of them. Search for "microinverters vs power optimizers " in youtube.

UnhappyCustomer

https://www.boards.ie/discussion/comment/120528532#Comment_120528532

Thanks bullit. For anyone reading this post in the future.

"I've been told by one provider that I can either install the panels with the hybrid inverter or the enphase with the microinverters"

The provider was either lying or it was unbeknown to him (probably this). Microinverters can use AC-coupled batteries and apparently they are getting trendy now.

All thanks to Gary from the youtube channel bullit shared here. Not just he gives away a lot of information in his channel. He answer very quickly comments. Thanks!

bullit_dodger

Yeah, I tend to give suppliers the benefit of the doubt. Sure while there are many huckster snake-oil salesmen active in the marketplace, there are also some good reputable honest hard working suppliers too who want generally to do the right thing. Really the whole optimizers/micro-inverters situation will depend on your house and what issues you have and what is the best way to solve them. Optimizers (generally - not always!) can be avoided, but there are some user cases where they add value.

String inverters can (and do) use AC coupled batteries too, so I wouldn't let that dictate your thinking. For 9 out of 10 people, a string inverter is the way to go. Hybrid if you want to add a battery, but the math on a battery unless you go DIY isn't as good as it was 1-2 years ago.

That said, personally I think a 5Kwhr battery is a good thing, for a variety of reasons. Some backup in an outage to run a few low wattage things like the TV etc, but that would depend on how many outages you expierence.

UnhappyCustomer

I believe microinverters is what I need for 2 reasons.

1. I can fit the power of my setup to my current demand but if my electricity demand increases (electric cars etc) I can add more panels later on.

2. My house is like a cross and the roof faces all of the cardinal points. In the morning I get sun from one side, midday-afternoon other part of the roof and evening other part of the roof. By having a string setup I would have a low productivity the whole day.

Also there are trees around that give plenty of shade to some parts of the roof some parts of the day...

I think my case is a bit special based on what I learned so far.

In other order, do you have any help/videos/articles about DYI batteries? I'm greatly interested in that

con747

https://www.boards.ie/discussion/comment/120539529#Comment_120539529

Have a look at this thread for info on DIY batteries. https://www.boards.ie/discussion/2058246061/10kwh-lifepo4-diy-battery-addition-here-is-my-write-up/p1

bullit_dodger

https://www.boards.ie/discussion/comment/120539529#Comment_120539529

Yup - lot to be said for micro-inverters. I have 6x panels (installed myself) using micro-inverters. Although just be aware you can add panels (up to a point) on string inverters to. Typically 12 panels is the maximum that a "string" will take on a string inverter. Originally when I got my system installed I had 4 panels facing east on string 1, and 10 panels facing west on string 2. i then added 2 panels to east and 1 panel to west - so it's possible to add on....up to a point. I should say though that your BEST route is maxing the panels as you can from word go. Don't get a battery if that means you can get more panels. Batteries can be added later too. Adding panels, while it can be done.....it's always more troublesome getting a guy onto your roof than doing some internal electrical work.

I'm not trying to steer your thinking away from micro-inverters, only to make sure that your fully aware of all the pros/cons. I wouldn't like you to go the micro-inverter route thinking (mistakenly) that string inverter doesn't do x or y.

con747

https://www.boards.ie/discussion/comment/120539529#Comment_120539529

One bit of advise I would give is do your homework on all variations now, it will make life a lot easier down the road. Look at the section on the FAQ's "Does my site location make a difference" There is a couple of links there to see how much each orientation can generate per year and look here https://play.google.com/store/apps/details?id=jp.gr.java_conf.siranet.sunshine&hl=en_US&pli=1 to see where the sun position will be during the year.

I have 3 strings, East- South- West with the west using optimisers. The East and South have 1 hour of tree shade in the winter from November - February but only from 11am and still generate enough for my base load with excess. Just make sure if you go down the string inverter route you get your NC6 in before the regs change.

UnhappyCustomer

Thank guys for all the information. I feel like this is something the people selling panels should do for me...

To be honest when it seems I'm convinced with one solution, new information comes up a ruin the whole theory.

I sid microinverters thinking of the shades...

But surely it will come somebody saying that string and optimisers are actually better and my head will melt again 😂😂

Would you guys like to tell what made you go for the setup you went for? Would you change something and why?

con747

https://www.boards.ie/discussion/comment/120541451#Comment_120541451

I spent 12+ months lurking on the quotes and numerous other threads taking info on board a couple of years ago and about the same researching what I would need. I pulled the trigger and got installed in February 22. I since added extra panels to get to 5.5kWp and doubled my battery to 10kWh with a 5kw hybrid inverter. In hindsight as has been said here numerous times max your panels from day 1 to save costs afterwards.

Luckily the extras I got done cost very little, 4 new panels a change over switch and fireman switches removed so panels can supply power in power cuts. SEAI require the fireman switches for grant so wait until chance of inspection has passed if you go that way. You should have a fair idea where and when the shade of the trees happen so use the links to have a rough idea if you need optimisers or microinverters.

If your installer is half decent they should be able to guide you. I topped all my perimeter trees after install but there is one large oak tree I await a storm to take out because it's not on my property. Do your research and try get it right the first time is the best advice.

DC999

https://www.boards.ie/discussion/comment/120541451#Comment_120541451

When you day shade, what do you mean? A chimney? Trees? There is a difference as once the sun rises it will get above trees - certainly in summer.

Take some pics of the roof at times of the day and see what the shadows do. And see if you have old photos of the roof to compare at different times of the year.

UnhappyCustomer

https://www.boards.ie/discussion/comment/120540988#Comment_120540988

While technically you can add more panels to a string, in reality that would tie you to a single installer/provider as no other provider would like to touch anybody else's work and I'm not sure if even the same provider would add panels due to possible warranty conflicts. That's why I think microinverter could be helpful here.

https://www.boards.ie/discussion/comment/120541494#Comment_120541494

I see a couple of trees around in different parts of the day and different seasons. I thing I decided to chop one of them but not just now.

https://www.boards.ie/discussion/comment/120543223#Comment_120543223

There is a massive beech at the west north of my property and cover the roof from 6/7 until the end of the day. Not possible to cut, the tree is just gigantic

Seasonal photos is a really good idea. I would have a look at my photos to see if I find something. I would wait and doing it but I'm in a bit of a rush now, I want to get this panels sorted asap.

bullit_dodger

Don't worry about shading outside of 9am -> 6pm. Sure it will affect production in those hours, but it's minor compared to the main production hours. For example, here is my production profile for April 20th just gone. Best day of the year so far.

You can see that before 9am and then after 6pm (where there are trees across the road) the production is mimimal. that's ok. Sure, it'd be nice to get an extra hour or two, but the main bulk of the production is there between 9am-6pm.

Aside: Couple of clouds at 12pm-2pm.

As for suppliers not wanting to touch another persons installation. While that is generally true - it's more the internals inside the house that they tend to care more about. What's on the roof is (generally) more standard. If anything Micro-inverters would be the lesser known of the two. 90%+ of installations in Ireland are string inverters. Again, I'm not saying that to dissuade you away from Micro-inverters (I've used 6 of them myself on my shed installation - good devices), but just want for you to be fully aware, so that your not basing your decision on false assumptions.

It's hard for people to give advice as we don't know your roof layout (perhaps screenshot a picture from google earth?), but without seeing it.....I'd probably go with a string inverter and maximise 2 of your roofs. 1 string for each roof and then run that for a year. Then after that time I'd look at your production verses need (consumption) and decide if you want to go the extra roof. That one I do with micro-inverters - but again, it's difficult to know

UnhappyCustomer

https://www.boards.ie/discussion/comment/120545407#Comment_120545407

This is the lovely shape of my roof. You can see the shade of the massive beech in the left. There is another tree in the right that it is covering during the morning (very likely to be taking down). Would you still recommend string? I think based on the shape of the roof, the performance of independent panels here and there would be the optimum way of getting the maximum out of it.

I was wondering... if the installer says based on the panels installed you will get 8kw (for example) and you don't get them, are they liable for that?

bullit_dodger

You could probably do something like......

String 1 would have both the west facing roofs (as they are all facing the same way, they can be on the same string), and then string2 could host the south by south east ones. Without dimensions (not that I want them)....I'm eyeballing the number of panels you can fit. But a string inverter would have no issues with that config. 12 being the panel limit on a string - but it does depend on the inverter and the panels. Some of them you can only have 10 or 11 panels for voltage reasons.

You also have a lot of land, might be worth considering a ground mounted array to the north of the house? Google earth is great, but of course it doesn't give an appreciation for the height of the trees.

UnhappyCustomer

https://www.boards.ie/discussion/comment/120545811#Comment_120545811

This is a 21 panels proposal I got (string)

The trees are 10-11 meters the one on the east and 13-14 meters the beech in the west.

But what's the benefit of string over microinverter apart of maybe the price?

Wouldn't the shade of the tree reduce the overall performance of the with string as per the Gary video you shared yourself?

DC999

https://www.boards.ie/discussion/comment/120545747#Comment_120545747

Taking a step back, seems like you're torn on the decision of string inverters V micro. Or are you comfortable with using string one now? Micro inverters are good in some cases but often for smaller DIY setups. As Bullit has said. You’ve a huge roof and space around for ground mounts. I’d suggest strings are the better setup for you. Then once that decision is made in your mind, you can focus on getting a design that works for you. The vast majority of people here have string inverters (for good reasons) and that’s what the installers use by default. Micro inverters would be great for my retired folks who have low usage and don’t want to fork out a lot.  

In case it helps, my roof is somewhat similar. I’ve panels on E, W and S. On E it's on 2 roofs - main roof. Plus flat roof,, which is only one with optimisers due so shading that moves during the day. We get solar from very early to very late in the brightest months. 

If shading is an issue, there are options with string inverters. Optimisers for the shaded ones (assuming parts of the string suffer shade during the peak sunshine hours). Or you can get a 2nd inverter (I’ve 2). So then you can have up to 4 strings and if one is shaded it won’t impact the other strings. You’ll need to challenge installers based on my experience as they want an easy life. More roofs mean more work and longer cable runs.

It's a pain to get solar installed - was harder than I expected. But I'd do it again tomorrow if we moved house. Only live 10months but it's amazing. So stick with it.

UnhappyCustomer

https://www.boards.ie/discussion/comment/120545950#Comment_120545950

You are right. I don't mind string or inverter. I just want to make sure I get the power promised. If they say you get 20 panels and 8kw of power. What happens if you don't?

bullit_dodger

https://www.boards.ie/discussion/comment/120546150#Comment_120546150

Well, you won't. :-)

Well, like many things in solar..... the answer is complicated. I know what you meant, but the panel/inverter combination has a whole load of factors in play. For example, they are very temperature dependent. The sun on the panels on a hot day would generate 10-20% less than the same sun on the panels if there was a cool breeze blowing. Then there's the angle of the sun to the panels. If the panels are more "end on" as they would be in winter, they won't produce the same amount as the sun beating straight down on it. Then there is the roof orientation. When the south facing roof is getting good production, your west facing one would not be.....so there's a lot of things to factor.

You might have 8.0kwp in panels, but not all those panels would be facing the sun at the same time as the sun moves around the sky.

Don't worry though, it's rare that a system doesn't do what it's designed to do. if you get in 7Kwp of panels with (say) a 5Kw inverter, you'll most likely get that 5kw for a large amount of months.

Go back to basics though. Look at your bills, see how much your using , then see what kind of system you'll need via

JRC Photovoltaic Geographical Information System (PVGIS) - European Commission (europa.eu)

UnhappyCustomer

https://www.boards.ie/discussion/comment/120546356#Comment_120546356

This is what I got from a 8.6 kwh instalation

graememk

https://www.boards.ie/discussion/comment/120546857#Comment_120546857

Because you have multiple aspects, you'll have to split up the panels on the JRC it's won't be all 8kw at 45degrees.

bullit_dodger

Unfortunately with that site, you have to do each roof individually as what you have there is 1 roof with 8.6Kwp in panels due southeast (azimuth of 45). So you have to plug in whatever you have south east, and then get the forecast for that.....and then do the process again for the West facing roof and add the two together.

It won't be TOO far off, but it will be a little lower I think, like 10% or something. So with that, you should ahve a look at your bills and see if this covers your bills then for the year. This will then give you a good indication of if you've sized the panels correctly.

If you haven't, this is listed in the FAQ section. You should have a read of that.....has a lot of good stuff in there.

Interested in Solar PV? Read this FAQ first. — boards.ie - Now Ye're Talkin'

UnhappyCustomer

https://www.boards.ie/discussion/comment/120546895#Comment_120546895

I understand the principle but how does that change the overall result?

So imagine I get suggested 21 panels to give me an overall 8.6kw in the 45° roof. Which I've worked out in that.

Sorry while I was typing I had an epiphany. I suppose what you mean is that calculating all sides I could get even more?

MightyMunster

https://www.boards.ie/discussion/comment/120552834#Comment_120552834

I think they meant to calculate the overall you'll have to do a few calculations e.g.

10panels on south roof

Plus

5 panels on west roof

Plus

5 panels on east roof

To get your overall, rather than just putting in 20 panels on south roof

bullit_dodger

https://www.boards.ie/discussion/comment/120552856#Comment_120552856

That's exactly it Mighty.

The sun is generally in the south, so if your panels were facing due south on your roof, you'd have an "Azimuth" of 0 as "0" = south on that website. If your panels were facing "south east", you would have an Azimuth of "-45" and if they were facing West it would be "+90". Unfortunately that site doesn't have a way to enter in two separate solar arrays in the same calculation, so you have to do each roof separately and outside of the website add up the values.

I know from doing it previously it will be within 10% less, but still....if you want a more accurate result that's how you do it.

UnhappyCustomer

https://www.boards.ie/discussion/comment/120546356#Comment_120546356

You mentioned here that if I have 7 kwh of panels and a 5kw inverter, I will get 5kw.

Is the inverter a bottleneck? I didn't fully understand that. Also I got a quote for this setup that I like

Supposed to be 7.8 and it will be 6.3 based on JRC calcs.

https://www.boards.ie/discussion/comment/120552856#Comment_120552856

Thanks for the clarification. I did it know but to be honest the azimuth is a bit confusing. And I suppose it has in count the best case scenario.

https://www.boards.ie/discussion/comment/120553368#Comment_120553368

I leave the 14% loss percentage

bullit_dodger

Is the inverter a bottleneck? I didn't fully understand that.

If you had all your 7Kwp in panels facing south and the sun was actually in the south, then yes, your inverter would be a bottleneck if it's only 5Kw as that's the maxiumum that it will process ... for lack of a better word.

However in your case, you have two roofs with panels. Some of your panels facing south, and some of your panels facing west. When the south facing ones are at max power, the west facing ones will be "end on" to the sun and not operating at 100%. Similarly later on in the day when the west facing panels are directly pointing the sun, the south panels won't be at 100%. To give you a better understanding, here is are my two arrays. One facing east and one facing west.

Maximum power on the east was at 10:45am, but at that time the west facing ones were only doing like 1/3 of their max power.

In reality, it's a bit more complicated than that, but that's a brief explanation.

UnhappyCustomer

https://www.boards.ie/discussion/comment/120556483#Comment_120556483

While I understand that would be the case for a west/east system. Wouldn't ths be different for a west/south?

I feel there are three peak hours there where it could hit all the panels

bullit_dodger

Again, at the risk of sounding evasive.....it's complicated - and to explain all the details would take pages of text. It's a lot to do with temperature on the day, the angle of the sun above the horizon and not just the azimuth (south/south west) above which you have in the picture, the slope of your roof etc. the haze in the atmosphere. etc etc. etc.

For example, above in my chart for East/West production. Perfect blue skies day. You can note the maximum for my west array was 3.4Kw ....even though I actually have 4.18Kwp in panels. Similarly on the east array I have 2.28Kwp in panels, and yet the max I got was 1.7kwp even when the sun was shining directly onto the roof.

In reality with 7Kwp in panels, even if you had an unlimited inverter, there would only be a few days a year where you'd get all 7Kw in production. With a 5kw inverter, you will be "clipped" for a small time on the glorious days, but overall you'll lose only 2-3% of your overall output. Nothing to worry about.

UnhappyCustomer

https://www.boards.ie/discussion/comment/120558338#Comment_120558338

Did you do the maths to know exactly what would theoretically produce and what are you missing before putting up the panels or is this based on experience and tracking? I wonder if the investment to change the size of the Inverter is worth it?

I came with the idea of more panels, microinverters and bigger inverter and everything have been shutdown 😂

bullit_dodger

As it turned out, I did run the numbers on it before. Worked out about €30/year in the difference in production that you'd miss between a 5Kw and a 6kw inverter. Ballpark. The math is a bit rough-n-ready.

Couple of things to note. The 6Kw inverters that you are currently allowed to install will no longer be permitted after May 31st. New regulations mean that you can only have 5Kw of inverter power after May 31st. If you are installed before that deadline, your "grandfathered in". If your installing after that you would be in breech of regs.

Micro-Generators (esbnetworks.ie)

The advantage of a string inverter over a micro-inverter is that you can more easily oversize the array. Most people don't "get" this, but your panels DO NOT produce maximum power everyday. It's a rare day that they do. So what people do is they oversize the array to the inverter. With a 6Kw inverter you might install 8Kw of panels instead of matching 1 for 1 and installing 6Kwp in panels. So when it's a grey overcast day and your panels are producing only 40%, instead of 40% of 6kw = 2.4Kw generation, you'll be getting 40% of 8Kw = 3.2Kw, and of course your inverter can handle that and you get the benefit of the extra panels. Most days are like that.

With microinverters, it's much harder to oversize the installation as ESB will still only allow you that 6kw/5kw in "inverter capacity", and since it's usually 1 panel to 1x400 watt micro-inverter, you can't benefit much from oversizing the array.

As for what you should get, ultimately the decision is yours. Nothing shot down, people like me just trying to give you the info and leave the decision up to you so you can make informed choices.

Me? I'd go string inverter on 2 roofs a mentioned and see how you get on for a year or so. If you need more power then add micro-inverters for 4-6 more panels.

thatphil

https://www.boards.ie/discussion/comment/120559158#Comment_120559158

Re the micro inverters and over sizing I'm not sure thats strictly true. I have a small micro invertor system of 6x400w panels paired with 6 Enphase IQ7+ micros and these top out at 296 watts so the most I ever see from from my 2.4kWp system is 1.776. So clipping is something to be mindful of with micros too.

bullit_dodger

https://www.boards.ie/discussion/comment/120559204#Comment_120559204

Don't forget now that it's not the actual production that ESB Networks care about, it's the rated label on the inverter. If you have a 400w micro-inverter, and it's never (ever) produced more than 296w, ESB Network's don't care. It's will go down as a 400w as far as they are concerned. So 12x of those puppies and your are at 4.8Kw. Meaning when you want to get your 13th micro-inverter, your technically no longer compliant (reg's wise)....come May 31st when 5Kw is the new limit for a domestic house on a NC6 form.

This makes it harder to oversize the panels->inverter ratio. I sort of skimmed it above with the comment that it's "harder" to do oversize the arrary. You can do it with 2x or 4x panel micro-inverters I guess, but it's a little harder. The limit is inverter size, not panels.

your dead right though, it's easier to experience clipping with Micro-inverters, but in terms of regulation compliancy and the ability to hit 5Kw on more days of the year by having 6-7Kwp in panels, it's easier to do that with a string inverter.

As mentioned I've both, really like micro-inverters myself incase you think I'm dissing them :-)

UnhappyCustomer

https://www.boards.ie/discussion/comment/120559158#Comment_120559158

Given the website you shared "over 25A will not be eligible for connection under the NC6 Microgeneration connection application route."

What does that entail? You cannot be connected to the grid? You won't receive SEAI grants? Both?

Also you said, you can put string with a 5kw inverter and then if you want more, you could get microinverters. Wouldn't they count against the total 5kw?

bullit_dodger

So right now, you are allowed to install a 6Kw inverter. Has been this way for years, but they (ESB networks) are changing the rules whereby the maximum inverter allowed on a (free) NC6 installation is 5kw. This will happen on May 31st. After that, if you installed a 6kw inverter, you wouldn't likely be able to get the SEAI grant of €2400. You might still be eligible to get the grant on a NC7 submission, but that submission is guts of €1000 and it's not guaranteed that it would be approved. However on a NC7 you wouldn't be limited to just 6Kw either but way more potentially. 11Kw is it lads?

So to maximize the production you should get your install done promptly if you can.

You sort of found the issue with adding micro-inverters after getting the string inverter installed. Yes, you would be in breech of the regs. You would however would have obtained the 1x (and only) grant at that stage. It would be wrong of me to recommend that you should do that - but that's the story.

graememk

https://www.boards.ie/discussion/comment/120560856#Comment_120560856

The limit on the nc7 is 72amps (17kva) [hmm they seem to doing the calculation on 240v] on single phase.

It is also dependant on the grid, and your MIC (import connection)

I think the nc7 does allow for export limiting though.

slave1

You won't be allow export more that your max import I believe