Microinverters - The Future of Home Solar PV?

hi I'm Gary and welcome back to my channel Gary does solar in a previous video I said it was questionable whether micro inverters added much value when it came to shading on your solar panels but actually I'm not against micro inverters at all quite the opposite in fact I think they could be the future of home solar PV stay with me in this video and I'll explain [Music] so micro inverters are they a viable alternative to our beloved string inverters especially now as the global market moves from early adopters to mass adoption I carried out quite a bit of research into this over the last few weeks and I've come to the conclusion that for the home solar PV Market micro inverters are a much better solution than string inverters let me take you through that and who knows if you're thinking about getting solar it might give you some additional options to consider let's start by looking at what micro inverters are again micro inverters perform the same function as a string inverter converting DC power into AC power but each Act on a single panel whereas a string inverter acts on the whole string of panels Up on the Roof micro-inverters are first attached to the rails then their respective AC outputs are connected to the AC circuit of the home via the consumer unit to which all the home appliances are connected to here's what these micro inverters look like on an actual roof their respective DC inputs are then connected into the solar panels when they're attached to the rails sunlight hitting each panel will generate DC electricity which is then automatically converted to AC by the micro inverter for that panel and sent into the home additionally a micro inverter controller unit is also connected into the consumer unit and this is able to communicate with all the micro inverters for those interested the method of communication is not wireless but instead uses a special signaling through the AC wires this technology is called power line communication and there's a link in the description if you want to know more although there are many companies who manufacture micro-inverters in this video I'll be concentrating on end phase who is the world leader their controller unit is called Envoy this controller unit connects out to the internet via the home Wi-Fi or an ethernet connection and this allows the manufacturer's cloud-based micro inverter Management Service called Enlighten in the case of end phase to keep an eye on the performance of every single installed micro converter around the world pretty much in real time so already you can see micro inverters are very easy to install alongside solar panels and there's no separate string inverter to install either streamlining the whole installation process let's have a look at the many other benefits of micro inverters then here we have a house with three roof spaces east south and west and the west facing roof has a couple of valux Windows let's add solar panels to all three roof spaces we can easily fit 12 panels on the east roof we can't quite fit as many on the west roof because of the windows but we can manage six panels there and on the smaller South roof we can fit three panels if we were to wire up these with a string inverter depending on the power rating of the panels we might need to put the panels on the east roof onto two strings that's okay because most string inverters can support two strings the panels on the west roof would need to go into another string anyway because those panels are on a different orientation you should never have panels on different orientations on the same string as this will bring the total power output down therefore the three panels on the south roof would also need to go on their own string for that same reason and this brings another problem the size of the string inverters used needs to match the power output of the panels and three panels may not generate the minimum voltage required so for this particular house we'd likely require two string inverters of different sizes instead then let's look at how we would wire up all of these panels using micro inverters well that was easy we just wire them all up in series it doesn't matter that the panels are on three different orientations this is because micro inverters manage each of the panels individually so low generation of panels on the west roof in the morning will not affect the greater power being generated in the powers on the east roof let's take a smaller house now we can only fit three panels onto the South roof as there is a chimney if we were to use a string inverter we would have to size it correctly for so few panels but with micro inverters it doesn't matter how many or how few panels there are we just wire them up to the EC circuit as before so you can already see that with micro inverters it's easy to install solar panels onto any kind of property it doesn't matter how many roof orientations there are and it doesn't matter how many or how few solar panels each roof can accommodate micro inverters are just so versatile and that versatility doesn't stop there either let's consider expanding an existing solar panel installation for example let's say in a few years time the owner of the larger house wishes to add a couple more panels on the west roof underneath those windows like so with a string inverter any expansion requires the inverter size to be matched to the new string size to ensure high performance and usually this means the existing string inverter has to be replaced or a new string inverter added into the installation worse still due to the continual advances in technology over even a short time it's often impossible to get hold of the same panels that are already on the roof and having different kinds of panels in the same string even if they're in the same orientation is an absolute No-No for string inverters but for my micro inverters none of this presents any problem whatsoever we can simply extend the AC cabling into the new panels it doesn't matter if the new panels are of a different Power output or have a different panel degradation likewise if the owner of the smaller house wants to maximize the size of their array by adding an additional much smaller panel beneath the chimney that's no problem this extra panel is just wired in the same as the others and the micro inverters will maximize the total generation of all the panels even though the new panel generates far less power than the others another major benefit of micro inverters is their monitoring capability and whilst the string inverter can record all manner of statistics about each of the strings including power generation voltage and current they can't see beyond that they can't see what's going on with individual panels and that means if there's a problem with one of the panels there's a fair bit of detective work required in order to identify which one using the larger house again as an example if we look at the power output of the two strings on the east roof we might see that the first string is not producing as much power as the second 1.57 kilowatts compared to 1.89 kilowatts assuming all the panels in the second string are functioning normally you might make an argument that each panel is contributing roughly 315 Watts on average and based on that you might hypothesize that one of the panels may have failed in the first string but you don't know for certain and you can't determine which one from the information the string inverter provides and of course we're fortunate here that we had a second string with the same number of panels on the same roof orientation to compare power outputs with without this we'd have to compare against historical outputs for an equivalent sunny day at the same time of year okay to investigate more then we could use a thermal imaging camera and then our example here we can see that the second last panel looks to have some kind of problem wouldn't it be great if instead we could see statistics for each panel in addition to the whole string well that's another benefit of using micro inverters you can do exactly that here is the kind of detailed reporting that you can get using n phase micro inverters and this will be similar to other micro-inverter manufacturer systems you can view the power output voltage and current of each panel in real time and you can view all this from whatever device you like wherever you might be there's no doubt that the more data you have access to in any system the more informed you'll be about how it's performing and with micro inverters you get plenty of data the next benefit is what I think is one of the most important ones when thinking about a solution for the mass-market home solar PV there is no single point of failure with micro inverters let me explain what I mean by that here is a south facing solar array connected to a string inverter producing 4.8 kilowatts on a sunny summer's day if that inverter were to fail then you would lose production on all the panels and because the cost of that loss production is clear it creates an urgency to have that string inverter fixed or replaced for a micro inverter system however it's very different if one of the micro inverters develops a fault it only affects the production on the panel it is connected to in our system here that's only an eight percent loss sure the problem we'll need addressing at some point but there's no urgency now and even in the unlikely event that a second micro inverter were to fail sometime later the system is still operating at 84 capacity in my mind that's a huge plus point for a micro inverter based solution and not only for the mass Market my own solar setup is hopefully being installed in a couple of weeks time I've chosen a string inverter solution and it's too late for me to change anything but if I could I'd be seriously thinking about a micro inverter solution instead and not only for the benefits I've covered so far but everything else that I'm about to cover please don't forget to like And subscribe this helps my videos get more exposure so others can benefit and my next video will be about what I'm planning for my own solar setup while we're on the topic of failures let's look at micro inverter warranties most string inverters today come with a 10 year warranty which means if it fails during that time the manufacturer will send you a replacement unit you may still have to pay for an engineer to carry out the inverter swap though and that 10-year warranty is not just an arbitrary number string inverters typically only last 8 to 12 years before failing certainly worth keeping this in mind when working out the return on investment for your own solar installation and we'll be talking more about string inverter replacement later in this video with micro inverters the warranty is much much longer typically 25 years in fact why is that it's because these units are not having to manage the large voltages and currents associated with the complete array each micro inverter only has to manage the voltage and current for one solar panel and that means increased longevity and then addition to the lengthy warranty manufacturers such as end fees also provide a labor reimbursement program to go with it that means you get a free replacement micro inverter and a sizable contribution to the cost of swapping out the faulty one in Europe you can see here the contribution is 200 Euros if your property is single story that amount is likely to cover all of the costs to replace but if you're in a two-story dwelling it might not but I think the 25-year product warranty and the accompanying labor reimbursement program shows the confidence micro inverter manufacturers have in their products and I'm hearing that future micro inverters are expected to have 50-year warranties let's talk now about production optimization there are really four parts to this and so we'll start with shading a few months ago I carried out a fair amount of research into the effects of partial shading on panels both with and without optimizers and you can look at the results of that research in these two videos I've put the links to those videos in the description but here is a quick summary where you have hard shading on some of your panels like this from a neighboring house it's unlikely that micro inverters will be able to optimize your solar production any better than the bypass diodes inside the solar panels can do themselves but if you have shading from a service cable or TV antenna the micro inverter should be able to improve your production this is because there's not enough shading to cause the bypass diodes to kick in but there is enough to reduce the current flow through the entire string which in turn limits the power generation from the non-shaded panels and if you have diffuse shading let's say from a tree then for the same reasons micro inverters should be able to optimize your production next is dirt accumulation here is that same array and you can see that over a year or two Dart has accumulated towards the top left hand side of the array with micro inverters and using the monitoring capability we talked about earlier we can see that three of the panels are still operating at a hundred percent but the panel on the top left is only operating at 89 and the remaining panels are operating somewhere between those two values if all the panels were connected to a string inverter instead of using micro inverters what would happen is the generation of all the panels would be reduced to 89 percent and in fact this is exactly the same scenario as for diffuse shading from a tree a third area where micro inverters can help out with production optimization is panel degradation like micro inverters solar panels today generally have a warranty of 25 years but over that time the performance of solar panels can be expected to gradually degrade you can see this in the chart here the panels start at 100 efficiency slowly degrading to 85 percent efficiency after 25 years but in reality each power will degrade at a slightly different rate micro inverters will ensure Optimum production from each panel regardless of the differing degradation of other panels but with a string inverter because of the variances are all within a few percent of each other over that time production efficiency will be reduced to the worst panel in this case to around 77 percent at the end of 25 years finally in terms of production optimization although to a much lesser extent we can consider solar panel manufacturing tolerances solar panels have a tolerance during the manufacturing process for example a 400 watt panel can be expected to have a 5 watt tolerance what this means in practice is that this panel will output a minimum of 400 watts under Peak conditions but it might be able to produce an additional 5 Watts your string inverter will not be able to benefit from such an increase but with micro inverters you can another important benefit of micro-inverters is all to do with safety rapid shutdown is a critical safety procedure of solar panel installations required to ensure the safety of emergency responders and Electrical Workers during maintenance and repair activities during a fast shutdown procedure the electrical output of the solar panels is rapidly reduced to a safe level this is especially important in high voltage systems where the potential for serious injury or death is significant this safety procedure was already mandated in Most states in the USA more than 10 years ago and it's also mandated in a growing list of other countries around the world string inverters can shut off to prevent the energy generated by the panels from getting past the inverter but the panels will continue to generate electricity if the sun is shining which creates voltage and current on the cables between the panels and the inverter as a result most rapid shutdown regulations today require shutdown to occur at the module or panel level hence the use of module level Power Electronics mlpe such as micro inverters or optimizers to meet this function additionally when considering the possibility of arc fault fires micro inverters are inherently safer than string inverters because they never contain high voltage DC power if you're getting a lot from my videos and would like to support my channel here's my referral code for octopus energy if you live in the UK and if you sign up using this code we'll both get 50 pound credited to our accounts okay we've looked at the many benefits of micronverters let's now look at some of the potential drawbacks starting with the higher upfront costs today you'll pay more for a micro inverter solution than a string inverter one but we should consider those costs in relation to the expected lifetime of the system which we'll assume is 25 years as we saw before micro inverters typically come with a 25-year warranty so that covers Us for the lifetime of the system good australianverter on the other hand only has a 10-year warranty and is likely to fail around or after that time there will be a cost to replace that inverter but it will give you hopefully another 10 years or more and if you're unlucky this second inverter could fail before the 25 years is up and you'll have to buy a third unit so this extra upfront investment into micro inverters could well be worthwhile but remember micro inverters can fail as well and what's to say you won't have a couple of failures on your roof over that 25 years let's take a closer look at that now it makes sense to keep things simple on your roof the less complexity up there the less there is to go wrong let's take a closer look at the technology on your roof then starting with a typical solar panel well there's not actually that much a solar panel for domestic use contains 60 cells like this or 120 half cells very simple components they also contain three bypass dials attached to the back of the panel and that's it not much to go wrong there okay what about a micro inverter then let's take the lid off and have a look crikey that's pretty complex and having all of that complexity on your roof in all weathers and all temperatures that's surely a recipe for disaster no well to get a handle on all this we should take a look at the actual failure rates of micro inverters in the field here are some statistics from MC electrical down in Brisbane Australia they installed 3100 end phase micro inverters over a period of five years and in that time only three of those units failed by my math this gives an extrapolated failure rate over 25 years of 0.064 percent and here are some more statistics this time from pen with solar Sydney Australia they installed 35 000 n phase micro inverters over a period of seven years with only 10 unit failures over all that time this works out to an extrapolated failure rate over 25 years of 0.026 percent n phase's own published failure data is 0.05 percent which is between those two values so we'll go with that what does 0.05 mean in reality then well if you have a solar array comprising 10 micronverters the chance of having a micro inverter failure over the course of 25 years is about 1 in 200. pretty good odds if you ask me and actually it's a primary reason why pen with solar decided a few years ago to only sell end-phase products by the way the math behind this is a little more involved than just multiplying the 0.05 by 10 that's just coincidental and I've put a note in the video description to explain why and talking about coincidences as I started my research into this video just before Christmas a fellow YouTuber on solar technology Anthony Dyer noticed a problem with his own solar array now Anthony's array doesn't have micro-inverters but each panel does have a solar Edge Optimizer which is a similar unit to a micro inverter but doesn't convert DC to AC what Anthony noticed was that one of his panels was not generating anywhere near the same as the other panels around it and after a few days the panel stopped generating completely using the monitoring capability that comes with solar Edge optimizers he was quickly able to establish that the panel itself was fine you can see here that the panel voltage remains healthy throughout at around 35 volts but the Optimizer voltage dropped to zero on the 3rd of November and never recovered an Optimizer failure what I was interested in was what was the support and repair process like and Anthony very kindly supplied me with the details solaredge confirmed their side it was indeed an Optimizer failure and posted at a new unit free of charge Anthony then got in touch with his installer to swap out the old unit with the new one an electrician and Apprentice arrived on site and the whole process took just over two hours including erection and dismantling of a scaffold Tower thankfully Anthony wasn't charged by his installer but it may have been the installer recouped some or all of those costs incurred via solar Edge's labor reimbursement program similar to the one end phase has Anthony's property is also single story so the scaffolding effort was slightly easier and perhaps less costly I wonder then would there be out of pocket costs for those with two-story properties we'll talk more about this shortly and if you want to find out more about Anthony's experiences with solar and also EVS I thoroughly recommend you subscribe to his channel and I've added a link in the description one other potential drawback of micro inverters which many are not aware of is power clipping for example the latest micro inverter product from enface the iq8 is only rated for 388 Watts any extra power generation from your panel will be clipped that means if you have a panel that can output say 415 watts and many of the latest panels can do that you'll always lose 27 watts of power at Peak generation that's over six percent surely that can't be right I'm afraid it is but before you dismiss micro inverters completely just on that point let's analyze what this means in reality here is a chart that will show solar generation across the day we'll plot a line showing Peak generation for our 415 watt panel and then layer in the sunshine and now we'll plot another line showing the maximum power rating of the optimizer 388 Watts you can see that the amount being clipped compared to the total generation throughout the day is actually a very small percentage around about three and a half percent and remember this profile is for a panel on a south facing roof in the south of England on a mid-summer's day for the rest of the year and if your house is on a different orientation you won't get near that threshold and there's another Factor as well remember we're looking over a 25-year Lifetime and so we need to take into account panel degradation that we spoke about earlier this is what this looks like for our 415 watt panel if we consider the height of Summer after 12 and a half years we no longer breach the micro inverter power limit and it falls further as we get to 25 years and so although micro inverter power clipping sounds alarming in reality it's not really something to worry about in my view at the start of this video I said I believe micro-inverters were the future of the home solar PV Market how did I get to that conclusion well imagine you were in charge of a government program in your country to roll out home solar PV to everyone who wants it a mass Market installer if you will what would your solution requirements be looking at the market up to today it's really been about early adopters early adopters tend to want to choose their own equipment from a wide range of Manufacturers and products out there and that will result in highly diverse solar installations across the country one person system will be very different to the next person early adopters also don't mind lots of electronic system boxes and wiring in their property whether that be in the garage the loft or a utility room and they're happy to see lots of system data being produced on a daily or even real-time basis and they're even happier to be able to adjust various system settings to achieve the most efficient use of their generation contrast this stem with the emerging Mass Market they want a no fuss installation which hopefully results in hardly any system Hardware being on show or even present at the end of it they expect everything to just work without any intervention from them for the full lifetime of the system just like their electricity meter or their consumer unit does today and if there is any problem they expect to be notified about it and they expect it to be repaired in a timely manner ideally under warranty and if they ever sell the property they expect there to be a straightforward Handover process to the new owner and for those that want to add extra elements to their system like a battery or a solar diverter they expect that to be possible without any fuss back to you then as a mass-market installer what are your own requirements in light of that well you'd want to limit the number of solutions that you supply to the market that's better for stock control and should also provide you with economies of scale and bargaining power with your suppliers there would also be less training to contend with and easier support for the many installations you make which would eventually number in the hundreds of thousands or potentially even millions and you'll certainly expect reliable performance over a 25-year time frame for the solutions that you supply ideally with full remote monitoring capability and in the event of any installed system failures you'll want to ensure there is a low-cost straightforward repair process in place so I think you can see where this is going only a micro inverter based solution will meet the needs of the mass market and the installers tackling that market they provide a single solution for any type of property that is also straightforward to install and despite a higher upfront cost they're more cost effective for the customer in the longer term micro inverters already exhibit High reliability today and they're getting even more reliable all the time and all of this is backed by lengthy warranties 25 years today and soon to be 50 years and if there is a micro inverter failure it will not bring the whole system down taking the pressure off for an immediate need to repair the only nickel I have is could there be a cost to the customer for those repairs will the cost of the scaffolding to get to the roof of a two-story property be more than the labor reimbursement costs in the warranty we'll have to see but there are already companies out there developing highly cost effective scaffolding solutions that could be the key thanks for taking the time to watch this video and for all your support over the last six months with my channel until next time 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Channel: Gary Does Solar

Views: 224,842

Keywords: microinverter, inverter, solar

Id: q6t0AAi5Jws

Length: 25min 41sec (1541 seconds)

Published: Mon Feb 06 2023