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re: wind and sun resources
31 dec 1997
tooie wrote:
>> >trace ms130: 130 watt 29 to 50 vdc input, 120vac/60hz output $485.00
>> consider the cost of the parts. wait a bit...
notice the spec for at least 29 volts of input voltage. that can make these
more efficient, with fixed semiconductor junction drops. what's the efficiency
of this inverter? the first stage in a "backwards lamp dimmer" might be a
dc boost circuit, to raise the voltage to about 400 vdc. that requires a few
more parts not present in a lamp dimmer. so does power point tracking. does
this trace inverter do that?
>...just how long shall we wait?
good question. as of last year, about 5 companies were working on
these things. trace is apparently the first to sell one. i guess it's
no surprise the price is high, since the volume is low and there's no
competition yet. but the one i saw was about the size of a cigarette pack,
and it seems to me that these can be cost-reduced easily, which would
probably include building them into windmills (with easy heat sinking)
or pv panels, or removing some features like the rs-232 interface. one
rule of thumb is that consumer electronics sells for 4-6 times the cost
of the parts...
i guess we haven't seen many of these grid-tie-only "inverters" because
so far, pvs and small windmills (larger ones use induction generators)
have only made economic sense in stand-alone applications, which require
sine-wave synthesis and battery charging and discharging, and higher power
levels, with transformers and heat sinks. the cost of stand-alone inverters
probably can't be reduced much, although they are comparable to pc power
supplies in complexity, which are very cheap now, because of the large
product volume and number of manufacturers...
it seems to me that grid-tie-only backwards-lamp-dimmer inverters will
be made in larger volume (which is extremely important for the cost of
electronics, vs pvs) when or if pvs become cheap enough to make economic
sense for non-hobbyists in grid-tie-only applications without batteries.
ul and other regulatory approvals will slow this down, but if the need
is there, they can be mass-produced and cheap, like lamp dimmers.
nick
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