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Comment: Re:Is this surprising? Twice as many stars (Score 1) 119

by buback (#47567295) Attached to: The Milky Way Is Much Less Massive Than Previous Thought

So then really what they are confirming is that inference; that matter and dark matter are in a 1/9 ratio, and that if our galaxy has x stars and Andromeda has 2x stars, then Andromeda will also have 2y dark matter mass to our y matter mass.

That seems to be a more interesting finding.

Comment: Cosmic rays (Score 2) 76

Protecting from solar radiation is great, but i understand that the greater threat is cosmic rays. Solar radiation is somewhat easy to block, because you just put a light element shield, like hydrogen tanks, between the astronauts and the sun.

Cosmic rays are much harder to shield from because they are so high energy. They also come from everywhere, so require a omnidirectional shield.

Comment: Re:Extremely expensive (Score 1) 735

by buback (#42289157) Attached to: Solar Panels For Every Home?

As you say, better generators cost more, and the power they generate is significantly more expensive than grid power. You would need to have a lot of power outages and spoiled food in order to break even on the cost during the usable lifetime of the generator.

A $2-3k generator and the cost of instillation is about 30% of the equipment costs of a solar installation, and the equipment is getting cheaper all the time (labor costs are flat or increasing). And a solar installation will pay for itself half way through it's warranted lifetime (about 1/3 of the way through it's usable lifetime).

Comment: Re:Ending congestion? (Score 1) 648

by buback (#39969153) Attached to: How Would Driver-less Cars Change Motoring?

Yeah they would. Imagine perfect, zipper-like merging at highway speeds, and merging into a single lane to route around accidents, road work, or freight. The cars can all break and accelerate as one, and cars with equal acceleration/deceleration would be grouped together.

There is no lack of capacity on American highways. We could even reduce the number of lanes in each direction to two if everyone had driver-less cars.

Comment: Retrofits aren't usually cost effective (Score 1) 85

by buback (#39516171) Attached to: Ask Slashdot: Home Testing For Solar Roof Coverage?

I took a solar installer class, and learned that it's usually not cost effective to retrofit a house. Few houses have the proper size roof at the right angle to maximize efficiency. If there are trees in the way you can't cut down, just forget it.

but lets assume you want to find out anyway. well, you first need to look at how much power you use, because it will impact the size of installation you'd need. add up everything that draws electricity in the house. You'll probably find you need a much bigger array than you have roof space.

Now, that will be the size of the array at optimum efficiency. you'll have to subtract out all the efficiency losses for incorrect angle and shade, and add extra panels in order to get you back up to your needs.

I'm assuming you need certified installers in Floria because of the hurricanes, plus you'll need to get an electrician to install the inverter and breaker boxes, and probably a second electrician from the electric company to wire it up to the grid. If Floria has installation rebates, you'll need to do everything up and up in order to get your rebate.

So, first thing first: find a way to reduce your power draw by at least 1/3. it'll start saving you money now, plus you'll need a smaller array if you do commit to installation. it's much cheaper to start with efficient appliances and adequate insulation than it is to overcome it with more solar panels. Panels are getting cheaper, but labor costs are at least half of the costs. and while equipment costs go down, labor costs are flat or rising. If you build a house, build it with solar in mind and you'll save a ton of money up front, and you'll break even much much sooner.

Vax Vobiscum