Google Offers a Million Bucks For a Better Inverter

In addition, a thin square shape (a special case of the rectangle) would have the smallest surface area of any rectangle. So, a long, narrow rectangle would be best.

It's certainly useless for PV applications over a lot of the earth's surface. This thing is supposed to have an input voltage of 400v via a

10R resistor, in other words simulating direct connection from the panels. There's no battery and the inverter isn't grid synchronised. What happens when a cloud passes over? If the input voltage drops below a set level (I forget what it said) then it will shut down, I assume. Not many PV panel assemblies are going to reach 400V output in a typical UK summer anyway. :)

Nobody would design a real unit without grid-tie and variable input considerations. In fact, they mentioned grid-tie as optional useful feature. However, it would be a big liability if they require it and something goes wrong in prototyping and testing.

That 10 ohms is quite optimistic for a PV string.

With 30 "12 V" panels in series set to produce 450 Vdc total, each panel would need to generate 15.0 V open circuit. With 10 ohms total, there is a 45 V drop or 1.5 V/panel or 13.5 V from each panel at full load.

Look at the V/I curve for any "12 V" panel (intended for charging "12 V" batteries), the 10 ohm total equivalent series resistance makes a lot of sense, but still far from real situation with clouds etc.

There was a more or less failed attempt to standardize 42 V (3x12V batteries) as new car electricity standard. Much attention was paid to semiconductor load switching.

Of course 42 V is far too low for real electric vehicle drive train.

On a sunny day (Thu, 24 Jul 2014 21:59:16 +0300) it happened snipped-for-privacy@downunder.com wrote in :

I asked google: what voltage does tesla car run on?

It says: Lets do the voltage first. 9 bricks X 3.6 volts X 11 moduals = 356.4 volts. But the Tesla specs say the battery is 375 volts. Backing into the nominal voltage needed to get 375 volts each battery has to have a nominal of 3.78 volts. Technical Battery Discussion | Forums | Tesla Motors

Cool from google is not it!

Why would anyone want grid-tie for private PV panels, except for some sick subsidy systems, such as in Germany.

Close to the equator (say +/- 40 degree latitudes from the equator) the annual peak electricity consumption is in the summer afternoon due to air conditioning load. At that time all electric production capacity, including the expensive gas turbines are running. If the electricity is billed according to hourly production costs, private PV arrays makes lot of sense.

In this case, private PV arrays capable of feeding your air conditioning system makes economic sense.

At higher latitudes, in which the peak consumption is in the winter or spring/autumn, private PV arrays do not make much sense.

and the USA.

With or without subsidy, you can store the energy in the grid when not using it. You don't constantly use the same amount of energy.

Free (or cheap) battery, with zero subsidy.

What about rain? It makes no sense any way, any how.

Except when it's cloudy. It does get hot on cloudy days.

They don't anywhere.

Yes, the 10 Ohms would be intrinsic to the PV array. Although, it's not really as simple as being a "resistor", it's much easier than having to buy a PV simulator which could cost $10K to $15K or so...

I'm pretty sure that this design is based on the assumption it is a typical 600V maximum open circuit PV inverter. They never run them quite at this limit because when the weather gets cold, the Voc of the PV array goes up.

PV maximum power point is approximately 80% of Voc.

450V times 1/0.8 = ~562 V dc (below the 600V max limit) so this makes perfect sense.

boB K7IQ

Den torsdag den 24. juli 2014 20.59.16 UTC+2 skrev snipped-for-privacy@downunder.com:

the 42 volt was never about making the drive trina electric, it was about making things like water, oil and ac pumps electric so the placement was free

just the savings in copper wiring alone might make it worth while

-Lasse

Grid tie inverters can also be tied to a battery based inverter by "AC coupling" which can supplement AC loads as well as charge the batteries through the bi-directional battery based sine wave inverter.

boB

,---- [ ] | The problem is household inverters are too big?roughly the size of a | picnic cooler. Making them smaller would enable more solar-powered | homes, more efficient distributed electrical grids, and could help bring | electricity to the most remote parts of the planet. `----

How many domestic appliances inherently require AC power? The only one I can think of is the synchronous-motor electric clock, and I don't think anyone is making those now that the quartz clock is ubiquitous.

You only need an inverter if you want to run something designed to use an AC mains supply. Electronic devices generally use DC power internally even if they have an AC 'power supply' built in; motors in such things as fridges, vacuum cleaners, power-tools, etc, are usually designed to use AC not because AC motors are necessarily better than DC motors, but merely because the mains supply 'everywhere' has been AC for decades (for reasons that made sense in about 1900).

If you aren't connected to an existing AC mains supply, then an inverter is only a short-term solution until makers of electric motor appliances get around to making them with DC motors. If you're currently living somewhere that has no electricity supply of any sort, I don't think that running granny's old 240 volt AC Hoover is likely to be a high priority

- much more sensible to get a DC appliance to go with your new DC supply.

So Google are asking the wrong question. Eliminate the bulky inverter by not having an inverter at all, use DC appliances from the start; spend the prize money encouraging appliance makers to use DC.

--
-- ^^^^^^^^^^ 
--  Whiskers  
-- ~~~~~~~~~~

Valve lifters.

Those savings would be offset by the increased electronics costs. Those costs are rising much faster than anything else in the car.

There's still a weird issue here with this "reasoning" on their part (unless this reasoning was written by the copywriter who had no idea what they were talking about).

This page

indicates that a 250w solar panel is 1.64m by .992m in size. Or 1.626 square meters. Four panels would provide 1kw of output (assuming the rating is not based upon "perfect sun").

Four of these panels would be 6.5 square meters in surface area. If we ignore the volume consumed by needing to tilt the panels towards the sun and just go with needing a 6.5 square meter area, then what does not make sense is:

I need 6.5 square meters of area for 1kw of solar panels, but I'm going to not install them because of a picnic cooler sized power inverter? Somehow I doubt the volume of the power inverter is the deciding factor here.

Actually the reasons that made sense in 1900 still make sense today. It is trivial to convert AC power up and down in voltage levels with extremely high efficiency (minimal loss from the conversion). Just run it through a step-up or step-down transformer.

Transmitting megawatts of power over long distances at very high voltages (240kv and above) significantly reduces the resistive losses in the connecting wires. Power loss from resistance is to the square of the current. Stepping DC up and down in voltage is not nearly as easy so we'd either have to put up with extremely dangerous voltage levels at our end points (homes/businesses) or put up with extremely large energy losses in transmitting the power over long distances. Neither makes for a good outcome.

But stepping AC up from the 5-10kv at the generator station to 240kv or

480kv for transmission, then back down to 22kv for backbones in cities, then down to 120v or 240v for end point use is trivial, with little loss (comparatively), and significantly safer for all involved.

The Sunny Boy inverters use a 600v string for better efficiency. SO I don't understand the 400v input here. What is so special about 400v?

Cheers

illiterate septic imbecile. "

You just abused a comma. You are reduced two steps in rank of the grammar polizia and fined thirty kronheimskys. you are also on probation for a time not to exceed when we decide.

Thank you for your participation. Note, your 2017 dues are due at the end of the month. We are collecting them up front in case Hillary wins.

On Thu, 24 Jul 2014 17:16:23 +0100, Pomegranate Bastard Gave us:

The idiot who wrote "electrotric" is the imbecile, and you as well for being too goddamned imbecilic to catch where the real stupidity was actually centered.

Where the f*ck is your head at?

Bwuahahahahaha! BRL! Types I & II!

The Pommy Bitch Retard "chimes in again" with more utterly meaningless tripe.

BRL!

On Thu, 24 Jul 2014 18:31:52 -0700 (PDT), snipped-for-privacy@gmail.com Gave us:

YOU are a Usenet Line length Idiot and abuser of the forum conventions.

72 character line length, idiot, NOT HTML interface lameness.

BRL!