Re: Wind Turbines and Heating Water

["patrick_o_matic" <patrick@xxxxxxxxxxxx>]

Hi Graham
I have been looking at/designing a similar installation recently.
Here are some fairly random thoughts:

- What is the power storage for? 500W isn't much.
- The normal rule of thumb is to size the battery store based on the number
of days 'no generation' that you might have endure. e.g. three-four days
successive calm days (or cloudy days for solar).
- Battery life is contingent on depth of discharge. Ideally you want to
size your batteries so that they're not discharging more than 20% on
average, 50% worst case
- The battery discharge characteristics in off-grid situations such as
yours are quite demanding chemically. Not sure which Yuasa batteries you
are planning on using, but normal leisure-style batteries are not up to the
job. Wet batteries are perfered. Traction-type batteries are particularly
well suited (e.g. forklift truck type cells). In case you didn't know, it's
generally not a good idea to extend an existing battery bank over time, or
replace individual cells within the bank.
- You ask about voltage. Broadly speaking, the higher voltage systems are
more efficient (lower resistive losses in transmission). 48V inverters are
readily available (I think Sunny Boy are available in 48V variants). You
may also want to consider splitting the inverter, so that intermittent
loads (e.g. lights) are driven from a load-sensing inverter and continuous
loads are driven from an independent inverter. Inverter load curves vary,
but they are generally more efficient when operating at the upper end of
their load range.
- You will need a dump load as well. It may make sense to use this for
space heating?
- I don't really understand the motivation behind splitting the battery
banks and then controlling charging? What is the underlying driver for this
behaviour - is it being sure there is capacity in one of the banks for
essential services or something else?

Feel free to mail off-list if this is getting too OT for UKHA

Cheers
Patrick

--- In ukha_d@xxxxxxx, Graham Kiff <graham.kiff@...> wrote:
>
> Hi Guys
>
> I need some electrical expertise/advise...
> I don't think this is too off topic as I plan to integrate this system
into Cortex (Idratek) for control and monitoring.
>
> I'm planning on installing a Hornet 1Kw (max output 1.4Kw @ 70mph)
wind turbine with the intention of heating hot water and dumping any excess
back into the grid.  My question is, do I go for the 12/24/48v version of
the turbine?
>
> The DC Immersion heater is a 48v 1200w element
> The Inverter is a 24v 500w Sinergex
>
> I was originally planning to use 6 x Yuasa 12v 4Ah batteries in 2
banks (2 x in series = 24v and 4 x in series = 48v), but am not sure about
the configuration now and would like some opinions.
>
> Should I maybe try to find a 48v inverter?  Is 500w enough considering
the turbine can output up to 1400w?
>
> I plan on switching the charge load between banks using a 440Amp
Regulator/Controller, which will be switched by an Idratek QRH module,
triggered by Thermistor sensors on my hot water tank connected to an
Idratek QAI module.
>
> TIA
> Graham
>
> Links:
> Immersion          http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=120510484340
> Inverter               http://uk.farnell.com/sinergex/spwe500-24/inverter-sinewave-24v-500w/dp/9570721
>
>
>
> [Non-text portions of this message have been removed]
>




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