We've been using a battery based system since 1977, first using a 1930s vintage wind turbine, then a 1940s Jacobs, and started adding PVs to the energy production mix around 1981, as an off grid system. We then moved in 1989 to a place with an existing grid connection and added our wind/PV system. Until 2 years ago the system was grid connected using the grid as back up only , and then we added more PVs with grid tied microinverters. Last summer we replaced our VW Golf electric conversion with a year old Nissan Leaf, justifying it in part because it would use some of our surplus energy from our PV/wind system (the local utility just pays avoided fuel costs so using the electricity to replace gasoline as a vehicle fuel makes sense to me). Our current battery is a 24 volt 1500 amp-hour lead acid set, similar to a fork lift battery, and is about 15 years old and still going strong. It is about 3 days storage for us not including charging the car. I'm not sure how many more years we will get out of the batteries, but our set that we used in the 1970s and 80s was a used telephone company set, and lasted 12 years and was scrapped because we moved, not because it had gone bad--and today's battery monitoring equipment is much better than just monitoring battery voltage which was the choice years ago. The answer to needing a huge PV array and gigantic battery is to REDUCE YOUR ENERGY CONSUMPTION!! Our system provides all of our electric energy needs including charging our Leaf, and we have almost 4 1/2 kw of PVs plus the wind generator which might produce 100kw-hr in a good month (we aren't in a particularly good wind area, and installed the generator because we had it on hand).
When our lead acid battery needs replacement, we will be looking at a couple of options, including going to a battery-less grid tied system, a new lead acid battery, or a used Lithium battery such as a used Leaf battery. Given the direction that the utilities seem to be moving in, going back to an off grid system with a new battery sounds better and better. In the past, friends that used Nickel-iron (Edison) batteries found that the voltage range from discharged to useful charged to charging voltage was too great for existing charging systems and inverters. they aren't as efficient as lead acid or lithium, either, as far as I can find ou. -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20141222/fd3c5601/attachment.htm> _______________________________________________ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org For EV drag racing discussion, please use NEDRA (http://groups.yahoo.com/group/NEDRA)
