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Forum Index : Solar : 240 volt AC solar panels are here!
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yahoo2 Guru  Joined: 05/04/2011 Location: AustraliaPosts: 1166 |
Will this be a new direction for solar or a turkey with its head stuck in a bucket 
Tindo Solar have opened a new plant in Adelaide and are building panels fitted with the Enecsys micro inverter. This means no high voltage DC on the roof. Given that two building fires have already been blamed on panel wiring in SA this past year, with no evidence I might add, I can see some potential for marketing this. If there was a possibility of using them off-grid, it would change the way stand alone systems are wired for sure. yahoo I'm confused, no wait... maybe I'm not... |
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WindyMiller Regular Member  Joined: 05/04/2011 Location: United StatesPosts: 62 |
Yahoo2, Interesting article. I wonder how this is going to work out? Still have to rectify and store the energy in batteries I would think? Not in less someone is coming out with my personal favorite not going to happen anytime soon urban myth. The fabled AC current storage battery. All kidding aside they are really working on a battery for AC storage that could eliminate the need for DC storage in these setups. Damn that would be cool. Charge up the AC battery overnight and with enough of them run the bloody fridge during the day when there is no wind where I live. You would not have to mess with inverters or DC at all. Well I can dream can't I! Robert |
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| yahoo2 Guru Joined: 05/04/2011 Location: AustraliaPosts: 1166 |
There are two big advantages to something like this. The DC circuit is simple and short, just one link from batteries to a master inverter/charger that would controls the whole system. This cuts the cost of high amp wiring and fittings. Eliminating the high DC voltage circuit from the panels-through a controller-to the batteries means there is no need for breakers and fittings that can snuff a high voltage DC arc. With 240 AC as the backbone of a system the individual parts can be modular and standardised. components can be added to a system to expand or change it without redesigning from the ground up and buying all new stuff. At the moment it is still much cheaper for a small off-grid system to run generators for large loads than to expand the renewable energy side to cope with them. There is a growing market for battery/grid-connect systems that will supply power in a blackout, it's not a big leap from there to designing fully off-grid specific components for a 240 AC system. yahoo I'm confused, no wait... maybe I'm not... |
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| Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406 |
O/k I will bite.... Now suppose you have one of these AC solar panels and it merrily puts out power at 50.001 Hz And you buy a second one that puts out power at 49.999 Hz, and you connect them up in parallel. What do you suppose is going to happen when they drift in and out of phase with each other ? While connecting dc panels together in very large arrays is not uncommon, some diodes can fix most of the problems. But with ac voltages that may be different in both voltage and phase, I can see some fairly major problems arising. Maybe I am missing something, but to me this seems a very backward step. Cheers, Tony. |
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| yahoo2 Guru Joined: 05/04/2011 Location: AustraliaPosts: 1166 |
Micro inverters are not autonomous. They either grid connect and test the integrity of the power supply by pushing the boundaries and shut down if the Hz or voltage can be moved. Alternatively a master inverter controls everything in a similar fashion to ethernet over power lines or canbus. Each inverter has an ID, then it is possible to set the system to "island" off-grid. I'm confused, no wait... maybe I'm not... |
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| Sprocket Newbie  Joined: 03/11/2012 Location: AustraliaPosts: 8 |
Hi All, I have just had 2.8kW of panels installed using this technology and no probs. The Enecsys micro-inverters (made in USA) now have a guarantee of 20 years and the panels are efficient. I have a small wireless module connected to my modem, which picks up the individual data from each panel and transmits it to a WEB site from which I can extract daily weekly monthly or yearly production and shows totals. Because the voltage is AC 240V they are smaller and have connectors that prevent miss-connection. The system IS expensive but another panel can be added at any time without regard to a central inverter and if one panel fails it is only a matter of disconnecting that panel and replacing it without affecting the rest. Only took a day to install. Only thing I don't like is the fact that my data has to go to a WEB site instead of directly to my computer- and one other, no ability for daylight saving to time indication, so one has to mentally allow when looking at the daily readings. |
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| Georgen Guru Joined: 13/09/2011 Location: AustraliaPosts: 462 |
Could you tell us how much? Also does your system get any FIT from grid supplier? And are they OK with you getting extra panels later on? George |
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| Sprocket Newbie Joined: 03/11/2012 Location: AustraliaPosts: 8 |
Hi George Cost was about $12k and at present I get no FITS but the contractor is in negotiations. Having downsized from a rather large home, on the seashore, cost wasn't a worry. I don't know about the extra panels being allowable but government policies in NSW are changing all the time and when the time comes I have some vague idea of switching in panels facing West, in the afternoon. We are reasonably high and in summer there is still light until late. The main advantage is not relying on a central inverter that has minimal guarantees attached to it and the fact that there is no complexity in wiring, breakers etc. It clips together. I also like the idea of supporting Aussie. manufacture although I have no doubt that the purveyors of other brands will soon latch onto the idea of micro inverters. On another note, I have a friend on a farm looking at them and was wondering if one could run a pure sine wave inverter off battery to provide the nominal voltage/freq. to get them running. Without mains power, I mean, or would the inverter o/p impedance be to high or be damaged by the u/inverter o/p's. |
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Downwind Guru Joined: 09/09/2009 Location: AustraliaPosts: 2333 |
what happens on cloudy days when the panel volts drop? being just 1 panel and not a string they have a narrow operating window, once they drop off line how long before the inverter switches back online again. Have you checked if the panels are actually approved for use in NSW as my understanding is they are (or will be ) banned with the current micro inverters without the addition of a switching relay fitted, they have a low current leakage through the inverter when off line that NSW regulations will not except. With future panels the brand of micro inverters will be changed to solve these problems. Sometimes it just works |
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| Sprocket Newbie Joined: 03/11/2012 Location: AustraliaPosts: 8 |
Essential Energy has approved the system using the Enecsys inverters. |
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| Downwind Guru Joined: 09/09/2009 Location: AustraliaPosts: 2333 |
Yes i know they have up to now, but things get recalled or regulations change and if it poses a danger to lines men they can demand it to be disconnected. Sometimes it just works |
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| Sprocket Newbie Joined: 03/11/2012 Location: AustraliaPosts: 8 |
Hi Guru Had Essential Energy techs here a few days ago and as far as they were concerned the system passed. Have not had a look at the production window but each panel appears capable of producing very small output w/out dropping out. As you seem very knowledgeable in this area, would a system like this, on a farm, run with a battery operated pure sine inverter fed to it as the "standard". Perhaps the inverter would fail with the output from the panels fed to it???? |
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| Downwind Guru Joined: 09/09/2009 Location: AustraliaPosts: 2333 |
The question is what is the "Pure sine wave inverter that is used" In most cases yes it can be done but some inverters wont like it, so until more information is known the answer is best not to do it. Many factors come into play, like the base load and how many panel inverters are used, what happens is there is no way to back the panel inverters off if supply is greater than demand, so the inverter voltage will rise and they will shut down. In my case i use a sunny island inverter charger, and a sonny boy inverter on the panels, these are designed to work together, as when the supply is greater than the demand the sunny island inverter increases the frequency from 50hz to 52hz, the sonny boy sees the increase in frequency and backs off the output. With a standard GTI and battery inverter, this is not the case so the voltage rises and the inverters shut down thinking there is a fault. Pete. Sometimes it just works |
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| Sprocket Newbie Joined: 03/11/2012 Location: AustraliaPosts: 8 |
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| Downwind Guru Joined: 09/09/2009 Location: AustraliaPosts: 2333 |
Yes i full understand how they work when grid tied, and my comment was in reference to used with a off grid system, of which you asked about. Its the inverter on the battery system i asked for more information on. not the enecsys microinverters. Pete. Sometimes it just works |
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| Sprocket Newbie Joined: 03/11/2012 Location: AustraliaPosts: 8 |
At this stage it is still in the gestation stage and I have no idea what type or brand. Can you suggest any? Another thought I had was, being off grid, what effect would a Honda generator with inverter output have as it could then act as a stand alone backup for nights and cloudy days. The particular one in mind has the ability to reduce drive as required by the load and they can also be run in parallel. Bob |
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| Downwind Guru Joined: 09/09/2009 Location: AustraliaPosts: 2333 |
To be honest Gordon is the man to speak to on what would work best here for a off grid combo, unfortunately Gordon is no longer on the forum to offer his knowledgeable advice in these areas. From my understanding any transformer based off grid inverter will allow the H-bridge to conduct backwards, meaning it will work as a inverter charger, so excess AC from the panel inverter will backfeed to the batteries, once the batteries stop assorbing power, then the panel inverter voltage will rise and the GTI inverters will shut down. Now the way the GTI shut down and what is required to bring them back on line, or if they will cycle etc, I am unsure of. Without knowing what inverters are used where, its a unknowen quanity to offer advice on. If it was me i would use panels with a string inverter (series/parallel panels)and a system designed to do the job like i have with the sunny island and sonny boy inverters. If its an existing system one wants to add to using this method it can be done if the parts match. If its a new system in design, then why reinvent the wheel, when there is systems designed to work this way. Pete Sometimes it just works |
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| Sprocket Newbie Joined: 03/11/2012 Location: AustraliaPosts: 8 |
That may have to be the way we go. Thanks. Bob |
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