Posted by email@example.com on December 15, 2010, 8:25 pm
I got SPAM from china on grid tie inverters today... wonder if they
are related somehow?
Posted by BobG on December 16, 2010, 1:13 am
I think grid tie inverters need <5% distortion, which someone said
needs at least 7 bits. If you want 1200 watts for example, thats about
10 amps. Lets say you have a 0.1 ohm current sense resistor between
the incoming line and the outgoing inverter. If you sample the line
and load side of this resistor at the peak with a differential amp
(you are measuring the instantaneous current across the sense
resistor), you can adjust the inverter amplitude to be a little
greater than the line voltage. If the diff amp out is more than a
volt, the current is more than 10 amps, disconnect. This is just a
theory dreamed up in my brain. It might be completely impractical for
many reasons that I dont know about.
Posted by Jim on December 17, 2010, 2:47 pm
My Sun 500G Chinese 500w inverters sample the line twice per second,
and make adjustments accordingly. I have a video on you tube showing
the internals, but alas, no schematic. However, the circuitry doesn't
look excessively complicated, but it works great.
Do a search on You Tube for WA5DXP, and there one other fellow has
them up also in his video. Mine was a 12V unit fused for 40 amps on
the other fellows was a 24v unit fused for 20 amps on input.
I don't think it could be built for anywhere near what you have to pay
for a complete unit, the components would cost a lot more if you
could find them.
Lots of info on You Tube search "grid tie inverter". I'm pumping
800+ watts into grid all day, plan to add more panels when finances
permit. Some fellows are pumping 2 kw+ and running their meters
Posted by Jim Rojas on December 17, 2010, 6:37 pm
I do agree that the small 250w grid tie units are cheaper to buy. But
the unit we are working on costs as much as a 250w unit to build, but it
allows up to 3000w. A Chinese 3000w inverter will set you back $00+.
Posted by The Ghost in The Machine on December 22, 2010, 9:59 am
YOU'RE INSANE...NIX THE GRID TIE OR DROP THIS PROJECT IMMEDIATELY.
SANE PEOPLE ARE LIGHTING CHRISTMAS TREES AND THEIR HOUSES THIS TIME OF
I WOULD HATE TO HAVE TO RECOVER YOUR INSIPID SOUL FROM YOUR CHARRED