Thanks to Max and Nando for their comments.
I went with 12v as that is what I know and being an Amateur radio operator I have a bit of 12v gear. Based on the comments, I am going to use heavier interconnects between the batteries. In about a years time when we have explored our land and chosen a site for the main house then I will revisit what I am doing with the house end of the power system. I am not eligible for rebates in NSW. Thanks Graeme VK3JUD/2 --- Nando <[EMAIL PROTECTED]> wrote: --------------------------------- Max: Indeed, you were right to the point and faster than me. 12 Volts based systems are TOO limited in scope. 48 volts should be the minimum that one should use., though I prefer a much higher voltage ( 240 volts ) Also, battery life is shorten if the charge drops below 75 %, which may occur often with the "defined' power daily usage. If Graeme can exchange the bought units for a higher voltage ones, he should do such effort, HEADACHES will be minimized to an absolute minimum. Though I am wondering what were the reasons to choose a 12 volts system. Regards Nando ----- Original Message ----- From: "Max Enfield" <[EMAIL PROTECTED]> To: <[email protected]> Sent: Saturday, March 05, 2005 7:23 AM Subject: Re: [microhydro] Comments please on my proposed system > > > Graeme wrote: > > > > G'day, > > > > I am moving to a property in northern New South Wales in Australia that has a > > 50m waterfall with a minimum water flow in excess of 3.5 litre / second. Our > > power usage is estimated to be about 8kw per day rising to 12 when house > > completed. > > > > Our initial house site will be about 900m from the bottom of the waterfall. > > > > I would like your comments of this proposed setup. > > > > hydrogenerator model M1/125 from www.platypuspower.com.au giving 240v AC > > > > transmission line 900m size ?? > > > > at house Xantrex Truecharge 40+i 40amp battery charger into 3 paralleled > > Concorde SunXtender PVX-2120L batteries (total 759Ah) > > > > Connected to the batteries will be a Latronics LS-2012 2000 watt inverter. > > > > Depending on the voltage at the end of the transmission line I may run > > household lights and always on appliances direct from transmission line. > > > > I have already purchased the battery charger, batteries and inverter. > > > > The M125 was chosen because of the 240v output and included controller and dump > > load ie self-contained with high voltage output. > > > > Cheers > > Graeme > > > Graeme, > > I am familiar with the Platypus Power turbine (although not the particular model > you mention), the Trucharge range of battery chargers and Latronics inverters. > Even though my reply will focus on the Australian context I have decided to post > it to the group, rather than to you individually, because I think it may contain > some points of wider interest. > > You do not say how far below the waterfall you intend to place the turbine, so > it is not possible to estimate what sort of penstock losses we should be > considering, but for now let us assume, conservatively, that the net head at the > turbine is 40m. At this head and a flow rate of 3.5 l/sec you can expect 750W > from the turbine. This equates to 18kWh/day, however there will be considerable > losses - the magnitude of these losses will depend on how well you manage the > transmission and power conditioning parts of the system. > > I expect you will be just be able to sustain load of 8kWh/day, but not > 12kWh/day. The key issue here is the battery charger (discussed below). > > Now for my detailed comments: > > 1. system voltage: > The equipment you have bought, in particular the inverter, commits you to a 12V > system and you may now not wish to change this. However, considering the power > levels involved this is not a good choice. 24V would be better and 48V better > still. > > You have chosen an inverter with a 2kW continuous rating. At full load, this > will draw nearly 200A on the DC input side. This is a very large current for a > 12V system and unless you are careful, losses in the cabling and fuses will be > quite significant. If you intend to apply for a government rebate then you will > have to comply with Australian Standard AS4502. Part 2 of this standard > recommends that continuous DC currents do not exceed 120A. I don't know how > strict they are on this point in NSW, but in Queensland where I operate, this > recommended value needs to be adhered to. > > 2. battery > Try and avoid parallel battery strings in a permanent installation. The reasons > for this are well known and can be found in any text covering battery selection > for renewable energy systems. This is particularly so in your case. If you try > and draw 200A from a battery where each string has a capacity of only about > 250Ah, then the slightest difference in resistance between the strings will > cause one string to be worked much harder than the others. > > 3. battery charger > Fortunately you have chosen a switchmode type of charger, which will be tolerant > of input voltage and frequency variation and still be able to deliver it's > nominated 40A. Even if it works at full capacity 24h/day it will be able to > deliver at most 11.5kWh/day to the battery. > > A rule of thumb for battery/inverter systems is that the average power delivered > to the battery should exceed the AC load by at least 30%, preferably 40%. So, > with a 40A charger you will just be able to sustain a load of 8kWh/day, > cetailnly not 12kWh/day. > > Regards, > > Max Enfield > Planetary Power > > > > > > > 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. The microhydro-group does not endorse products or support the advertisements in any way. > > More information on micro hydropower at http://microhydropower.net > > To unsubscribe: send empty message to [EMAIL PROTECTED] > Yahoo! Groups Links > > > > > > > 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. The microhydro-group does not endorse products or support the advertisements in any way. More information on micro hydropower at http://microhydropower.net To unsubscribe: send empty message to [EMAIL PROTECTED] Yahoo! 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