Hello Ray, I have a couple 60/100 kW SMA Sunny Island systems out there, systems with 100 kW generators, 400 kWh battery banks and generally token renewable inputs. I feel with this configuration we close maxing out what can be done with 48VDC.
Getting into the MW scale scares me to be honest. I think that will be well beyond what can be handled at 48VDC and is well beyond capacity of the SMA systems. Really need to look into higher DC voltages to handle this kind of current. If this was my client I would first look to the loads and see if there are any alternatives to the 250 HP motor. I have learned there are often massive levels of engineering overkill in the industrial world. What is the duty cycle of that motor, what does it do, etc? Would they be better to go directly diesel for that? In terms of system designs I'd investigate a direct diesel/PV interface skipping battery storage. Perhaps a group of 250 kW synchronized generators that can ramp up/down based on demand. Perhaps similar tech to what Tesla is doing in Australia. Kevin -----Original Message----- From: RE-wrenches [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Ray Sent: April-25-18 12:37 PM To: RE-wrenches <re-wrenches@lists.re-wrenches.org> Subject: [RE-wrenches] Large Off Grid Inverter? Greetings Fellow Wrenches; We are consulting on a power system for a large off grid facility that is currently operating on a 1500 kW gen set. The loads are enormous for normal off grid: in the neighborhood of 600 amps continuous at 480 v 3 phase. Surges are close to 2000 amps, but we are working on control programming to bring that number down substantially. That is due primarily to a 250 Hp motor start. (that's not a typo!). EPA and local regulations are dictating that the current generator be retired in the near future. Grid power is a possibility, but we need to offer a viable off grid option as well. My question to the group: does anyone have real off grid experience with large format battery based inverters? I've heard of some micro-grid systems running in Haiti on Princeton Power inverters, and Dynapower has a 250 kW inverter that has a "grid forming" mode. As we all know, it is easier to make claims in spec sheets than to deliver hard motor starting power in a remote location. We need proven products, with a track record of reliability. We are considering SMA type systems that use AC coupled PV to offset fuel consumption of a generator, but those seem dependent on the generator to maintain the stability of the micro grid during hard starting loads. Ideally we would want to reduce the generator run time to under 200 hrs/ yr and reduce its size to 500 kW. We have excellent solar resources year round, and the possibility of limiting operations during cloudy weather to meet these goals. Thanks, Ray Walters Remote Solar _______________________________________________ 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
