Theoretical 24kW PV systems

[Lion Kuntz]

I am doing an exercise on costing out the H2-PV world.

Basic assumptions are:

* 2,000 square foot rooftops are blue roof PV @ 13% efficiency polycrystal silicon.
* At 12 watts per square foot, peak hours are 24kW DC production per rooftop.
* Grid-tie pure-sinewave inverters.
* Housing development with all homes similarly equipped

What are the best cheapest inverter solutions?

Does something like a 30 kVA each or one 75 kVA per every 3 homes make more sense. Who are the people that make the utility grade inverters in this size range? I looked at Ballard (hence the 30 & 75 sizes), but what are some other choices?

In the southwest sunbelt such a housing development with 10 homes per acre, five acres, would be a net exporter of power, a mini-power plant generating 1.2 MW per peak hour.

What are the issues involved in this that I am least likely to be aware of, the secret "gotchas"?

[Rob Beckers]

Hi Lion,

First: Welcome to Green Power Talk!
Please tell a few of your friends about the forum. We're still at a stage where we can use all the members we can get.

Assuming that a 2000 sq. ft. roof will be all south facing and at the proper angle might be a bit optimistic. I suppose one could design a house to be that way, aesthetics would be another thing though.

As to large photovoltaic inverters, there's a company named SatCon that makes big ones. From 30 kW all the way up to 500 kW (http://www.satcon.com/products/altenergy/pvi.html). I'm not entirely sure, but I think they are originally a Canadian company (now they're in several countries). Then there is Xantrex, they are well known in the small-scale PV world. Besides their small inverters they also make big ones (http://www.xantrex.com/web/id/13/type.asp), all the way up to 500 kW. I'm sure there are more, but those are the two I've heard about.

By the way, it should be possible to run small inverters in parallel as well. Each inverter would handle part of the panels. That's another way to get to large power, though it's probably cheaper to get a single large inverter.

-Rob-

[Lion Kuntz]

Hi Lion,

First: Welcome to Green Power Talk!
Please tell a few of your friends about the forum. We're still at a stage where we can use all the members we can get.

Assuming that a 2000 sq. ft. roof will be all south facing and at the proper angle might be a bit optimistic. I suppose one could design a house to be that way, aesthetics would be another thing though.

Any house that can't live on it's solar income is ugly. Yes I agree with you on that. Architects ought to starve who can't get solar right. However, flat roof panels are fine, since 75% of all homes intercept significantly more solar energy than they consume electricity. In some instances it is better to have solar siding panels than solar roofs.

Here's some pictures of solar siding:
http://ecocity.us/P4P/Palace_Daylighting/Colorado_Court_Apts/ (http://ecocity.us/P4P/Palace_Daylighting/Colorado_Court_Apts/Colorado_Court_Apts.html)
http://ecocity.us/P4P/Palace_Daylighting/Solaire/Solaire.html

As to large photovoltaic inverters, there's a company named SatCon that makes big ones. From 30 kW all the way up to 500 kW (http://www.satcon.com/products/altenergy/pvi.html). I'm not entirely sure, but I think they are originally a Canadian company (now they're in several countries). Then there is Xantrex, they are well known in the small-scale PV world. Besides their small inverters they also make big ones (http://www.xantrex.com/web/id/13/type.asp), all the way up to 500 kW. I'm sure there are more, but those are the two I've heard about.

By the way, it should be possible to run small inverters in parallel as well. Each inverter would handle part of the panels. That's another way to get to large power, though it's probably cheaper to get a single large inverter.

-Rob-

That's what seems common now, but the individual prices are way out of line.

We need to get away, far way, from these patchwork implementations of meager efforts. America needs 60,000 square miles of PV and it needs it yesterday. What that translates into is 60,000 small-to-medium sized businesses operating one to several EMC furnaces making one square mile each of PV by ten years from now.

WE are no longer allowed the luxury of even pretending that 1 or 3 kW systems are in any way adequate. There is 5,381 square miles of single family houses in America that can absorb enough PV to run the residential sector if there wasn't a 50% penalty for energy storage for non-peak and wintertime hours.

You are not going to run a nationwide bullet train system on a patchwork of 1 to 3 kW systems. Forgeddaboutit!

You are not going to run 200,000,000 vehicle fleet of cars and light trucks on 1 to 3 kW PV systems scattered about here and there, whether they be H2-ICE, H2-FC, or PHEVs. It's never gonna happen.

One single modern subdivision with 50 homes 2,000 sq.ft. each with 13% efficiency Silicon PV rooftops (12 watts/sq.ft) will generate 1.2 megawatt-hours per peak sunny hour and big bunch of 1 kW or 3 kW inverters at $1,000 or $3K or $5K is just not going to even be considered unless they are cheaper than dirt in volume purchases.