Aloha all,
I thought Id share my experiences with the Tesla Powerwall on my own NEM system here on the Big Island of Hawaii. I added the PW to my existing NEM system (3.84 kW DC with Power-One micro inverters) about a month ago. I did so to have back-up power to my whole house in case of a grid outage. With the use of the Tesla Gateway, which acts as an automatic main disconnect of a max 200A utility service, the home effectively becomes a micro grid upon utility power going out. So what happens when the grid is down, the sun is out, the house loads are all being met and the Powerwall is full? The PWs brain automatically shifts the frequency from the nominal 60 Hz to 66 Hz which causes the PV inverters to shut down and wait five minutes before trying to reconnect to the grid. I had my multimeter connected to an outlet and watched the frequency shift from 60 to 66 to 60 and so forth through the course of the day depending on loads, battery storage level and PV power being produced. Here in Hawaii, given the large amount of DG connected to our isolated island grids, the four utilities across the state (HECO, HELCO, MECO and KIUC) are all requiring new advanced inverters to be able to ride through high frequency conditions as high as 64 and 65 Hz before dropping offline. Hence the need for ability of the PW to go as high as 66 Hz to be able to shut down PV inverters. Another thing thats worth noting is that certain appliances in the home are more sensitive to high frequency conditions. My microwave sounded kind of funny while operating at 66 Hz. Electronic clocks will run fast if the frequency is higher than nominal. Some washing machines will beep beep at high frequency conditions and so on. That said, I was able to do a load of laundry with both my electric washer and 240V dryer. As far as I know, though, none of these household appliances are damaged under this kind of high frequency condition. If any of you know otherwise, please let me know. Whats going to be interesting to see is whether theres going to be much of a market for adding battery storage, like the Powerwall, to existing NEM systems that dont have any storage and therefore dont have the ability to provide back-up power if the grid goes down. And Im wondering whether the experiences in Texas, Florida and especially Puerto Rico (where still about ½ of the islands residents are without regular power) will bring the value of back-up power to more top of mind awareness. After all, we already pay for all kinds of insurances in our lives. I wonder if were at the point where were willing to pay for an insurance policy to keep the lights on in case the grid goed dark. marco _______________________________________________ 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
