
Pre-built solar homes could make renewable energy almost 50% cheaper - elorant
https://www.inverse.com/article/59638-solar-homes-doe
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Waterluvian
I'm totally a layperson on the subject but the other day I thought about how
far more devices in my house use DC than AC than 30 years ago. It seems odd
that I convert solar to AC then back to DC.

I wonder if there's any future to running both an AC and a DC bus through the
house, or if that makes no sense for reasons beyond my basic understanding.

~~~
205guy
A friend of mine did something similar. He put in a small solar array with
only 3 panels, an inverter/charger, and 400 Ah of 12-volt batteries. This DC
then feeds into a breaker panel and goes to lights in all the rooms. He uses
LED spotlights, the little bulbs that plug into wires stretched across the
ceiling. He said he just ran 10-gauge Romex wires through the attic, down to
DC-rated switches and then to the ends of the cables.

He still has all the original 110 wiring and fixtures in the house, but this
battery-backed solar system runs all his lights. It can easily go 2 days
without sun before he needs to use the regular lights. Another benefit is that
DC LED bulbs are by definition flicker-free, and also low consumption (4-6
watts each) but bright. He calculated he can light each room better than
before with 6-8 bulbs, so 40-50 watts, thus only 4-5 Amps (@ 12 VDC) to each
room.

All the big appliances in the house still run off of of AC, but he does have a
110 inverter so that he could run a critical appliance such as a fridge during
an extended outage.

So this little system replaces 1-2 kWh of incandescent lighting per day (CFC
or LEDs on 110 would be less, but not flicker-free), while providing lights
during outages. He says it's not cost-effective (the usage displaced by solar
and battery usage doesn't cover the cost of the system), but the backup powers
is worth it to him.

~~~
holoduke
I am actually thinking of something similar. Instead of 12v DC I probably
would go for 48v or maybe even higher. With 12v your cables soon start to
become too thick to be practical if you want to run serious things like garage
doors / window shades etc.

~~~
205guy
My friend said he picked 12V because that's what the easily-available LED
bulbs are rated at, and he just wanted a simple lights-only system.

I guess you could pick whatever voltage you want for your loads and cable
runs, but you need to have the appliances you want available (or easily DIY)
in that voltage. It would probably be possible to convert down the voltage
once, but any more than that and you're introducing loss again.

~~~
Maakuth
On the other hand, you could connect 12V lights in series to get them the
desired voltage.

~~~
Scoundreller
That’s not always a good idea.

It is putting more current through each light.

And particularly problematic if each bulb has parallel LEDs and they start
burning out: then more and more current is put through the remaining LEDs.

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ksec
More than 50% of the Population will live inside Mega Cities by 2050 [1].
While it is good to have Solar cheaper for Houses, the reality is most people
won't have a rooftop Solar option.

Edit: This is not to say 50% cheaper is useless, it is a point of information
for people living in houses and not realise large population around the world
cant afford a house.

[1] [https://www.cnbc.com/2018/05/17/two-thirds-of-global-
populat...](https://www.cnbc.com/2018/05/17/two-thirds-of-global-population-
will-live-in-cities-by-2050-un-says.html)

~~~
gnarbarian
I hope that telecommuting will prevent this. The same amount of money can net
you a much higher standard of living in a rural area with less crime and
pollution and an all around better place to raise children.

Having half the world converge on urban centers scrambling to pay exorbitant
rent and taxes for the privilege of 100sq feet of personal space while sharing
an apartment with five strangers is misguided at best and dystopian at worst.

~~~
ben_w
> living in a rural area with less crime

I doubt “rural” will continue to be “low crime”.

In our fully automated future I expect criminals will also be telecommuting —
stealing, vandalising, or trading illegal substances with drones, drones which
are quite possibly either bio-mimicking or even bio-printed so as to make it
less appealing to shoot them.

~~~
rocgf
That is a very far fetched idea.

~~~
ben_w
Why? Drones are already used for drug delivery, bioprinting is a thing albeit
not an amazingly good thing yet, and biomimicry is demonstrated in occasional
TED talks and military spy drone demonstration videos on YouTube.

~~~
rocgf
There are so many weird angles to it that I just don't know where to start. In
a sentence, it's just a big leap to go from a couple of disjointed currently-
niche technologies to the conclusion that life in rural areas is unlikely to
be as safe in the future.

~~~
ben_w
I didn’t say “safe”, I said “low crime”. Overall safety might increase, but I
expect crime rates to go up everywhere as tech enables it. At least in the
next 10-20 years, beyond that is unpredictable change to too many aspects of
our world.

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droithomme
Passive solar for air and water temperatures is the way to design it into new
homes. Cool in summer, warm in winter. Few to no moving parts or electricity
needed. Little to ever replace. Anathema though to fancy solutions favored by
VCs like photoelectric utilizing the strip-mining of millions of hectares of
arable land, followed by toxic run-off, to produce panels and batteries.

For retrofits of existing homes, geothermal whenever possible for upgrading
central climate control when present. Current professional installers though
are generally incompetent and price-gouge. Sufficiently motivated hackers can
easily DIY.

~~~
blackomen6
Passive design can be climate specific, but I agree, it needs to be built into
new designs. The problem that I'm seeing is that "no one" cares: developers
will build houses with gorgeous kitchens/bedrooms/living rooms, but the HVAC
stem will be bottom-shelf equipment with flex duct run all over the place (and
pinched in a few other places). Because no one sees it, nor thinks to question
it. We really need to figure out how to make it desirable and something people
demand. Maybe that's raising electrical rates or taxing antiquated system
design? Some form of hitting a wallet?

I like what you're thinking about geothermal; it sparked a few thoughts,
though: Geothermal is expensive because of labor, not necessarily price
gouging. Most installers (in my area) put a 10% mark up on everything: finding
competent installers is harder and harder these days, so you're paying more
and more. HVAC techs can make six figures if they have the experience and
aren't afraid to negotiate. Unless, of course, they ARE price gouging, which
happens, especially if they're already busy (which has been the case for the
past three years).

The technology is solid, though to be frank, a high efficiency air-to-air heat
pump will be comparable to geothermal, depending on the climate zone. If we
can figure out a cost-effective way to replace gas-fired heat in northern
climates with something more eco friendly (and consumer friendly), progress
would be made.

~~~
generatorguy
Charging higher prices when demand is high is not gouging.

If people are making 200k At faang what’s wrong with tradespeople making 100k
when their skills are also in demand.

Everybody who supplies or resells equipment puts a mark up on it because there
is some cost for them to select it, procure it, store it, transport it,
finance it, etc.

~~~
Retric
In construction price gouging is often less about the rate than less ethical
charges.

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fyfy18
Why is it so expensive to install solar in the US? In the UK you can get a 3kw
grid tied system installed for under £5000 ($6100), and around double for a
9kw system - a lot of the cost is renting scaffolding and having people on
site to do the work, so it gets cheaper per kw as you have more installed.

~~~
craz8
I have a quote to add 13kw system to my house with a flat roof for about $40k

Then I’d get 30% back from the government - and my state has no sales tax on
this (which would have added 10%)

So, net cost to me of about $28k for a 13kw system

This does seem a bit pricey, but the tax rebate goes down a bit next year, so
we will likely do it this year

~~~
prawn
In Australia, I think a 13kW install would be quoted at about US$10k or less.
We put 5-6kW on at home, and 6-7kW at my small office building. Usually comes
out to around $1/W.

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sandworm101
For all the talk of AC v DC, that debate is moot. Current on-grid solar tech
integrates a spec inverter into each panel. In a net metering install (no
batteries, generators etc) this is far far simpler. No loads to calibrate, no
DC copper to run, no inverters to break, just plug the panel into the mains
and see your bill drop. That is the way forward for urban/suburban solar
power.

~~~
KaiserPro
not entirely. It will also cause brownouts at scale, as there is no secure
scalable way to stop production on peak solar days (save for shutting off the
supply, which kills the inverters)

solar + battery is a far better solution as it can soak up peak generation
_and_ peak demand.

~~~
adrianN
Once solar installations reach a scale where that becomes a problem, I'm sure
you'll find enterprising people who find ways to suck up extra power when
there is a surplus.

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velox_io
Here's a good video on the problems of transmitting power, and why we need
such high voltages.

How do Electric Transmission Lines Work?
[https://www.youtube.com/watch?v=qjY31x0m3d8](https://www.youtube.com/watch?v=qjY31x0m3d8)

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Animats
So why are the pictures on the site clearly of retrofits of solar panels to an
existing tile roof?

~~~
barney54
It’s a start up and just started working with manufactured housing builders.

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listenallyall
Corporate press releases get voted up to #2 on HN these days? Unfortunate.

~~~
smudgymcscmudge
It’s a Sunday. Weekend HN is a free-for-all. I kind of like it this way.

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jake_morrison
Combining the roof with the solar panels seems like a win. A very large
percentage of the cost of solar installation (50% last I checked) was labor.
So when it's time to redo the roof on a house, you can also install solar
panels. The interesting question is whether the panel lifecycle is the same as
the roof lifecycle.

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zarro
Regardless of the long term trends toward populations moving toward the city,
I don't see why most newly built suburban homes after 2025 wouldn't come with
a Tesla (or competitor) solar roof.

The 20-50k that it would cost would just get absorbed into the mortgage and
become an asset that would increase the value of the home - besides that, over
the over a 30 year period, if you are able to capture even half that value in
electricity savings, it becomes a no brainer as it would cost what a normal
roof costs anyway.

There are also the benefits of more efficient energy transmission and
resiliency of micro-grids as just bonuses.

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agumonkey
It's very annoying when the cost of something advanced comes from very trivial
legacy issues like that.

I wish someone develops cheap adapters while construction code gets update to
help panel frames.

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stretchwithme
It's always cheaper to design a feature into a product than to add it later.

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ckdarby
Wish I saw more CNC style designed houses :(

