Re: [RE-wrenches] 300W 72 cell micro inverters
Hi: It's all about cost versus benefit. The following goes through it in more detail. http://enphase.com/global/files/Enphase_White_Paper_Module_Rightsizing.pdf With large commercial systems, the best return on money invested is with 30% to 70% oversizing. JARMO _ Jarmo Venalainen | Schneider Electric | Xantrex Brand | CANADA | Sales Application Engineer Phone: +604-422-2528 | Tech Support: 800-670-0707 | Mobile: +604-505-0291 Email: jarmo.venalai...@schneider-electric.com | Site: www.Xantrex.com | Address: 3700 Gilmore Way, Burnaby, BC V5G4M1 *** Please consider the environment before printing this e-mail From: Dave Click davecl...@fsec.ucf.edu To: re-wrenches@lists.re-wrenches.org, Date: 02/10/2015 07:12 PM Subject: Re: [RE-wrenches] 300W 72 cell micro inverters Sent by: RE-wrenches re-wrenches-boun...@lists.re-wrenches.org Regarding the clipping, which the power electronics guys would rather I call power limiting... To be clear, Longer 100% production around noon (implied in that image that this is somehow beneficial) means this system could have produced more energy but didn't because the inverter was too small. Assuming similar efficiencies, a 300W micro-inverter clearly would have produced more energy on that day than the 250W inverter. I imagine that what you mean was that if you're locked into a certain ac limit here (either you can only use a 250W micro, or maybe your service conductors limit your ac rating) then yes, a higher dc/ac ratio may have more power limiting but will produce more energy at the expense of your kWh / kWdc yield (a consideration for some projects). Given that the ABB inverters have their highest efficiencies at the higher end of their power outputs, which is not where PV modules typically operate (unless you stick a 400W module on it), I'm curious whether a typical 280W module would actually produce more energy over a year with an Enphase 240W vs the ABB 300W in most locations. Over the full Enphase power range it's more efficient than the ABB: At ~100W dc input, Enphase is at about 96.4% efficient and the ABB 300W is at 95.8%. At ~250W input: Enphase 96.4%, ABB 96.1%. And yes, at 315W input: Enphase 76.2% steady-state, ABB 96.4%. It could go without saying (but I have momentum) that you should not spend $2000 on a larger inverter(s) that will help your array produce $200 more energy over its 25-year life. It's up to you to figure that out given your site conditions and as noted in the last thread that addressed this topic, weather data probably underestimates the benefit due to its averaging out most short-term edge-of-cloud effects. Anyway, maybe C250s would meet the OP's needs and they're actually the slightest bit more efficient than the standard 240W unit. That is, until you add the transformer since the output is 220-248V L-N. That presumably makes the ABB the efficiency winner, but hopefully the above is still useful. Sorry, no personal experience with any of the ABB/APS/C250 units. I probably should have opened with that to save you some time. DKC On 2015/2/10 13:05, jarmo.venalai...@schneider-electric.com wrote: Hi: One thing to keep in mind with clipping, (module over sizing), is that if a system has 10%-15% off clipping, that will not affect total annual energy harvest and depending on dust and temperature conditions will likely even improve it. Heres' a graph which shows the energy harvest graphically for a 250W module with a 250W inverter and a and 300W module with a 250W inverter. Please note the graph does not include any dust effects. To compensate for dust, the modules should always be of the order of 4% more powerful than the inverter, unless you plan on washing modules every month. Related to this, large commercial systems we have been supplying inverters to are 30-70% oversized as the sinking cost of modules makes the return on investment come out as maximized in that range of oversizing, JARMO _ Jarmo Venalainen | Schneider Electric | Xantrex Brand | CANADA | Sales Application Engineer Phone: +604-422-2528 | Tech Support: 800-670-0707 | Mobile: +604-505-0291 Email: jarmo.venalai...@schneider-electric.com | Site: www.Xantrex.com | Address: 3700 Gilmore Way, Burnaby, BC V5G4M1 *** Please consider the environment before printing this e-mail From: Drake drake.chamber...@redwoodalliance.org To: RE-wrenches re-wrenches@lists.re-wrenches.org, Date: 02/10/2015 06:51 AM Subject: Re: [RE-wrenches] 300W 72 cell micro inverters Sent by: RE-wrenches re-wrenches-boun...@lists.re-wrenches.org That would be at the 120% rating, so by rule of thumb, OK. I have a ground mount that has a ration of 1.15% with M-190s (figuring 199 W /
[RE-wrenches] Sunny Island Failure and various related issues
Friends: I have an existing service issue with a Sunny Island 4548 system shutting down unexpectedly. The system is off-grid with generator, two inverters, DC coupled charging. The batteries are a set of used Full River VRLA L-16s (3 strings of 8). We tested the at-rest battery voltages and they were good and consistent. The system was running fine and then experienced some generator failures. The inverters went into battery protect mode twice. We found and repaired the generator problem. A few days later, about 10 minutes after I assured the owner that all was well, the system shut down again. We responded and found the generator was willing and able to start. The reason the system shut down is not apparent. Here is what I have been told: 1.The system reports the temp sensor lead has been unplugged. There is a temp sensor and it appears to be connected and in good condition. SMA repeatedly points to this as a contributory cause but I have trouble figuring out how lack of a temp sensor cable could cause other than inefficient charging. We will replace the temp sensor tomorrow. 2.The system does not have a battery shunt. I am told this is also a serious lack because the inverter does not know what is going on with the batteries. I always thought the PV charge control and AC charge systems operated independently and the inverter responded solely to battery voltage. Maybe not so with the Sunny Island? Could the inverter shut down unexpectedly to protect batteries, even though voltage and SOC were at a reasonable level at the time? The system does report marginal SOH. We will install a shunt tomorrow. 3.Does anyone have any experience resolving mysterious shut-downs of Sunny Island systems and have any insight they may provide? 4.We download and read the SD data files in-house. We have developed some crude Excel macros that we use to paste the records into Excel and to hide and reveal selected columns. We find this tool to be very handy. I know that SMA uses an Excel tool as well. I have been meaning to ask if I may have a copy but keep forgetting. Do any of you analyze Sunny Island data files in-house? Do you have any tools or procedures that you could share or describe? 5.The Sunny Island line is significantly lacking in BOS equipment. They do not provide any AC or DC OPCD equipment nor do they provide any type of AC bypass. After we realized this we proceeded to provide an Outback FX1000 cabinet with every Sunny Island install, neatly mated to the system with gutter infrastructure. We provide Square D panel boards with custom interlock hardware for AC OPCD switching and bypassing. The SMA phone support technicians do not seem to understand the concepts behind this application and are automatically dismissive of the outboard gear and blame it for all problems. Below is a link to another system we had to work with SMA tech support on, and that we were never quite able to convince them that we knew what we were doing: http://www.millersolar.com/MillerSolar/Portfolio/Commercial/RM/R_M.html 6.I have had a difficult time working with most of the phone support technicians at SMA. From the very beginning most of them have presented an attitude of arrogance and condescension. I have had the quality of my work called into question without any evidence to support that position. I have experienced long delays in receiving replies. I have seen technicians present incomplete diagnoses. Fortunately Scoey Wildey of SMA was in town while we were rebuilding a commercial Sunny Boy system and he came and inspected our work and could vouch for it. I have found one highly professional, competent person at SMA who used to be in tech support who will take my calls. I'd like to give him credit but I don't want to share him. Also, Steve Jefferson and Scoey Wildey have intervened on my behalf on a few occasions and I am grateful to them. 7.I am wondering if anyone else has had a similar experience with SMA tech support. If it is not just me, maybe several of us could contact SMA management and ask that they augment the training of the phone support crew. I am sure they are capable of improving on their skills, both technical and interpersonal. We all know people in the industry that stand above the rest in professional demeanor, Rick Cullen, for example. I try to emulate his always-available, always-helpful, open-minded approach to dealing with people and challenges. We should expect this of all manufacturer's representatives. Thanks to any of you who are willing to review my many questions and offer suggestions or comments. Sincerely, William Miller ___ List sponsored by Redwood Alliance List Address: RE-wrenches@lists.re-wrenches.org Change listserver email address settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive:
Re: [RE-wrenches] Sunny Island Failure and various related issues
Hi William; Yes I'm getting too old to let manufacturers off the hook anymore. They just don't pay me enough (wink, maybe if I ever was compensated for service calls?) Unfortunately I have had the exact same experience with SMA's phone tech support. I was having setup issues that were not covered in the manual and they acted like I was an idiot. They walked me through it and I got it working , and then after I asked where does it say that in the manual? I then recited several verses from their manual that bolstered my faulty reasoning. He finally mellowed out a bit, realized I was somewhat knowledgable, and admitted it wasn't in the manual, and that they needed to update it. (hmmm...) Ultimately, I can deal with the attitude as long as they answer the phone and can fix the problem; it's better than someone being super nice but just wasting your time. Of course both fixing the problem and being friendly would be even better. Attention SMA tech support: William, I, and many on this list were installing off grid systems when you were still fudging in your diapers. We read the manual first, and only call when we still can't figure it out. We're the ones out there in the woods trying to make SMA equipment work while the nervous customer looks over our shoulder. Respect. Thanks, R.Ray Walters CTO, Solarray, Inc Nabcep Certified PV Installer, Licensed Master Electrician Solar Design Engineer 303 505-8760 On 2/11/2015 5:44 PM, will...@millersolar.com wrote: Friends: 6.I have had a difficult time working with most of the phone support technicians at SMA. From the very beginning most of them have presented an attitude of arrogance and condescension. I have had the quality of my work called into question without any evidence to support that position. I have experienced long delays in receiving replies. I have seen technicians present incomplete diagnoses. Fortunately Scoey Wildey of SMA was in town while we were rebuilding a commercial Sunny Boy system and he came and inspected our work and could vouch for it. I have found one highly professional, competent person at SMA who used to be in tech support who will take my calls. I’d like to give him credit but I don’t want to share him. Also, Steve Jefferson and Scoey Wildey have intervened on my behalf on a few occasions and I am grateful to them. 7.I am wondering if anyone else has had a similar experience with SMA tech support. If it is not just me, maybe several of us could contact SMA management and ask that they augment the training of the phone support crew. I am sure they are capable of improving on their skills, both technical and interpersonal. We all know people in the industry that stand above the rest in professional demeanor, Rick Cullen, for example. I try to emulate his always-available, always-helpful, open-minded approach to dealing with people and challenges. We should expect this of all manufacturer’s representatives. Thanks to any of you who are willing to review my many questions and offer suggestions or comments. Sincerely, William Miller ___ List sponsored by Redwood Alliance List Address: RE-wrenches@lists.re-wrenches.org Change listserver email address settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html List rules etiquette: www.re-wrenches.org/etiquette.htm Check out or update participant bios: www.members.re-wrenches.org ___ List sponsored by Redwood Alliance List Address: RE-wrenches@lists.re-wrenches.org Change listserver email address settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html List rules etiquette: www.re-wrenches.org/etiquette.htm Check out or update participant bios: www.members.re-wrenches.org
