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	Subject - Using the grid as a big battery Rosco I have been building a wind power generator and solar panels , I need advice on how to wire into the grid so I dont need to use batteries. JimmyDee I'm curious, are you going to pump back into the commercial power grid? I think that is the only way you wouldn't want to store the extra power. One thing to remember is they purchase for much less that you buy it back for. Jim Scott Vickrey Rosco, your ahead of the curve. I have heard of this and often wanted to do it, but I have never seen it done or been involved in a similar project. I did manage to find this site which talks about Selling power to the utility. I found a wealth of info on the subject searching "selling excess power back to the power grid" The best advice I can give you is to contact the power company and get their suggestion for equipment. We can then help you with the wiring details. I hope someone here can tell you more. Keep us informed on this. I bet this is a real safety concern for the linemen. Rosco Thanks for the advice I went on that site and read it . It was good and sends me in the right direction.However I still need to know more about the actual wiring into the grid . How dose that work? thanks Scott Vickrey I'm pretty sure they will be using a net meter. I have never seen one and would be interested in learning more. I strongly believe this will be more common in the future. I also think your credit per kilowatt hour will some day rise sharply when this type of power swap becomes more and more encouraged because it's green power. Does the wind generators generate DC voltage? Do they have their own regulators and or inverters? What does your electrical utility contract say about their requirements? Will they be installing a net meter? There is so much we don't know? Until we get some direction we can't help with any details. Go to your utility company and talk with them. If you can get some paper work specifically any schematics or diagrams they offer, scan them and email it to me at my email address. If they have this info on a web site that's even better, get the address. Either way I will post it here and we will work through it. I'm sure most people on this site would like to see this process being worked out from concept to operation. Gaining a kind of virtual experience for the future when they actually run into this situation. Chris Clement Rosco - I have a client doing this with a 2kw "Sunny Boy" system. It's output nets out of his utility purchase so he effectively sells that part back at the same utility price. It's very unlikely that he would, or could, have an excess that the utility would owe him money for. If that were the case, he would probably would get screwed. CozyGuy I'm familiar with photovoltaics, not wind, but it's pretty simple. The inverter is designed to take the worry out of this. It will accept a relatively high DC voltage input and convert it to single phase AC. It will monitor the utility and match the phase. If the utility cuts out, it will shut off it's own output as well. This is to protect utility workers, and is a requirement for a grid-connected system. A grid system simply won't work in an off-grid capacity. T he connection, at least in California, is the essence of simplicity. It connects to your panel through a dual breaker, and when it's output exceeds consumption, your meter runs backwards. The biggest gotcha is ground. Make sure you understand grounds and bonding. If your wind generator is DC output, it will work in a similar manner. Search on line for 'solar panels', 'inverters', or 'photovoltaic panels', and find some things to read. One of the biggest manufacturers of inverters is a German company called Sonny Boy. There web site has helpful study info. -- Len CozyGuy Points I should have made: 1) NEC 2002 describes some of the requirements. Things like a breaker on the DC and AC from the inverter, how to size panels, etc. This isn't enough, though- anyone who wants to do this should get some training. A few things: - DC wants stranded wire, not solid. - You can't run DC in the same raceway as AC. - The output of an array of solar panels is sufficient to arc. - The slightest shadow on a panel may drastically cut the output of the panel. - You need a device called a 'pathfinder' to determine when and where shadows will occur. - The wind load on a panel can be very significant, and mounting is critical. - There are very specific sizing requirements such as how the voltage output of the panels will vary as the season/temperature/path of the sun changes. - The inverter will shut off in the DC input falls below a certain threshold, or if the AC from the utility is not present. - An inverter for hooking to the grid is very different from an inverter for charging DC batteries. Since the batteries are charged with DC and only AC can operate a transformer, the entire voltage/ampacity issue is pretty much reversed. The panels are mounted in parallel or series/parallel, so the output voltage of the entire array is relatively low for a battery system. That means a grid system is pretty easy to use long wires with, since the voltages are larger, but a battery system often involves wire that looks like welding cable. You really can't go very far with low voltage. 2)Some power companies charge according to time of use. If you consume a lot of power when they're strapped, like on a hot afternoon, they'll charge more than they will at night when the air conditioners are off. If your system is making more than you're using, you're getting prime rates. If you turn the air off while everyone's gone, you could trade expensive power for cheap power. 3) PV is only cost-effective if there is a subsidy because a private citizen can't get paid for power, only credited by the utility. Don't make your system too big and expensive. 4) In CA if you're not a C-10 or General B, forget it. If you put electricity on the utilities' lines, you'd better play by the rules. Not to mention the expertise you must develop in order to deliver what you promise for the 10 years you're liable for the installation. Energreen Rosco, I'm in the PV business. Each state has its own policies regarding grid interactive PV systems. The first place to ask would be an energy authority that's run by the state. In New York, that would be the PSC, and NYSERDA. I can probably answer a lot of your technical questions. But here's where you can get info: NEC article 690 covers PV installations. Sandia National Laboratory has a FREE publication called Photovoltaic Power Systems and the National Electric Code:Suggested Practices. It was written by John Wiles. Anyone who is familiar with PV systems, is also familiar with John Wiles. This book is an excellent place to begin your code studies related to PV. And it's free. However, the code has had some changes since it was published. So use it as a study guide, and compare it to what article 690 says. Check www.sandia.gov to find out how to get it. It is really free. I've received several copies, and so have my clients. There's a magazine called Home Power that is dedicated to the topic of Solar and Wind energy, among others. www.homepower.com The most current issue is always downloadable in it's entirety, for FREE! But it's best to subscribe. Also, check out www.iaei.org . There are archived articles by John Wiles, which are intended to help electrical inspectors learn this stuff. I agree with some of the other posts here. But there's some information that needs to be corrected as well. The best thing to do is study what the experts have written, and get some training. I attended Solar Energy International in Colorado to get myself up to speed. www.solarenergy.org Their workshops are absolutely worth the time and cost. And it makes for a fun "vacation". Best of luck, EG