Wow, you guys on this list are awesome. I was gone for a few days after I sent that question, and I have so many emails! I'm going through it now and trying to figure out what in the world some of you guys are talking about... To clarify my situation, I am totally off grid. I have our main battery bank about 800ft away from the hydro site, and it is NOT an option for me to put the battery bank down at the creek. (b/c the main battery bank is actually a HUGE bank (48V @ 1700AH) that's also connected to a 15KW LP generator). I have a huge pure-sine inverter (rack of them) connected to the battery bank. Those are the fixed parameters... so it's unreasonable for me to try to transmit DC power for 800ft... it has to be AC... but my question was: is it better to get a DC hydrogenerator, then convert it to AC via transformer? Or is it better to just get an AC hydrogenerator? What are the downsides to getting an AC generator in my situation? --Daniel
Doug Lux <[EMAIL PROTECTED]> wrote: are you a totally off grid site or will you be net metered? I have my dc hydro's, batteries and inverter at the bottom of the pipe and bring power back to the shop at 120vac then I put it into an transformer to get to 220 to balance the load to the grid and to lower the voltage a bit with a tap to better center it in the inverters protection window. Its another 500 ft plus to the grid and the line would get soft at times causing the inverter to go off line in protection mode without the transformer. I ran the dc when I first started over 300 ft at 50vdc but the voltage drop was more than I wanted to give up even with 4/0 line. I also bring up a second ac line which is on the inverters output (as opposed to line input/line tie) to feed the house and everything I want to run when the grid goes down. For longer runs you can transform up to 480 and really cut down the line loss, but then you lose some of it in transformer losses. ----- Original Message ----- From: "danieldykim" <[EMAIL PROTECTED]> To: <[email protected]> Sent: Friday, February 11, 2005 11:30 AM Subject: [microhydro] AC vs. DC microhydro > > > > Hello, > > I'm kind of new to this microhydro subject, but I've been trying to > learn, after finding out that our newly acquired property has a year- > round stream... any help and info on this topic would be greatly > appreciated.. > > For our stream, the approx head is 120ft, flow is probably 70-80GPM > (what we can get out of the creek). With that configuration, we're > probably looking at a 500w system... but the problem is this: > > The creek is about 800ft away from the residence. That's too far > for any DC current to travel on a reasonably-sized wire. So some > people have pointed me toward AC hydrogenerators.. To have the AC > come up from the creek, and then convert it to DC (using the > inverter/charger) at the residence to charge the batteries. (we > definitely want to go with the batteries instead of using the power > directly, since this is a weekend-high-usage situation) > > Now the questions (if any of you could even answer just one or two, > that would be very helpful in getting me up to speed with this > topic): > > 1) I heard that AC hydrogenerators need to have some way of making > consistent AC voltage / frequency.. So does that mean I need to hit > the "lowest common denominator" by tuning the generator to produce > 60Hz at the lowest flow time of the season? Would that result in > wasting power? > > 2) How does the inverter handle the AC current from the > hydrogenerator, if it's not very consistent? (like if there's lower > flow one week). Does it matter? > > 3) Is it better & simpler to just get a DC generator (which is > cheaper), convert it to AC at the creek, and then move it up to the > residence, and then convert it back to DC? Is there much power loss > during those conversions? > > 4) I'm thinking of getting a 4-nozzle pelton wheel system, but I > also heard of some other systems like "stream engine" which works > better at low flow situations. Would my stream (120 ft head, 60 gpm > flow) work well with the pelton wheel? > > Thank you very much for reading. Any help would be greatly > appreciated. > > --Daniel > > > > > > > > > > > Does your company feature in the microhydro business directory at http://microhydropower.net/directory ? If not, please register free of charge and be exposed to the microhydro community world wide! > > NOTE: The advertisements in this email are added by Yahoogroups who provides us with free email group services. 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