
When will rooftop solar be cheaper than the grid? - leejoramo
http://theconversation.com/when-will-rooftop-solar-be-cheaper-than-the-grid-heres-a-map-54789
======
mikekchar
Where I live, it's already gobs cheaper. I live in Shizuoka prefecture in
Japan. We get about 2200 hours of sunshine a year at a latitude of about 35N.
I pay the equivalent of about 35 cents per kWh for electricity from the local
power station (hey, they turned off all the nuclear power stations and the
only fuel we have is gas from Russia).

You can buy solar panels in _any_ electronics store. If you go to the mall,
you will run into billboards and displays and salespeople wanting to sell you
solar panels. Already, if I walk down the street at least 30% of the houses
have solar panels. Lately virtually every single apartment building has put
solar panels on the roof. All the farmers are putting up vast solar arrays
because they can make more money doing that than growing food (which worries
me quite a lot... food security is pretty important for a chain of islands off
the coast of China).

I'm really curious to see how this affects pricing going forward.

~~~
pilom
Hawaii is another great example. $0.40-$0.50/kWh for their oil generated
electricity. Solar comes in even cheaper than the article mentions. There have
been so many solar installations in Hawaii that the power company has
effectively put a moratorium on installations that don't include storage
because they can't cover the swings in demand when a cloud rolls through town.

They expect things will get better once they install a connection between the
islands to connect their grids, but for the moment, the power company can't
handle the market penetration.

~~~
ZeroGravitas
> the power company can't handle the market penetration.

When it comes to solar power, and anything else with externalities, it's
always best to be clear whether "can't" means "has no economic incentive to do
so" or not.

In this particular case I'd say we are below the optimum level of solar, and
it's just poorly aligned incentives.

edit: just to re-iterate this in clearer language:

If they "can" do something if they spent $X million dollars, and $X million
dollars is less than the total amount saved by the economy of Hawaii by doing
so, then it's not a technical problem, it's an economic co-ordination problem.

If the utility is going to lose money from doing something, because they can't
capture all the resulting profit (like lower pollution meaning healthier
people) then their employees will say they "can't" do something, as no-one
gets promoted for making children healther on the utility shareholders dime.
Even though they could if someone gave them the money.

There's lots of BS surrounding solar, and a main thread of it is to pretend
that it's going to blow up the electrical grid. The only thing it destroys is
some current utility business models.

~~~
fefifofu
When clouds roll in, people are not OK with their TVs turning off. So you'd
always need the traditional grid in place, even if it's for a few days a year.

In that case, the utilities would charge a standby fee for keeping their
multi-billion dollar infrastructure in place (it's called a "demand charge" in
the utility industry). Then, when you use the electrons during the cloudy
period, you'd pay an astronomical "consumption charge", beyond $100/KWh
because everyone in the city wants/needs those electrons. The utility share-
holders would be fine.

But the people of Hawaii would have the cost of the solar installation PLUS
the cost of the traditional grid. The calculation in the article misses this
point and only shows the $/KWh consumption costs on the utility side.

So, yes, a huge amount of solar can figuratively blow up the electrical grid.

~~~
jakub_h
> When clouds roll in, people are not OK with their TVs turning off. So you'd
> always need the traditional grid in place, even if it's for a few days a
> year.

Sounds like a great argument for municipal generation and storage. If nothing
else, it's both cheaper than "everyone on his own" _and_ could lesser the
strain for long-distance infrastructure (which could still be nice for
geographic smoothing).

> So, yes, a huge amount of solar can figuratively blow up the electrical
> grid.

Demand-controlled EVs could take a lot of the load. In fact, it's probably one
of the sanest applications of massive solar installations (beyond the
potential of future power-to-gas tech).

~~~
astrodust
There's a lot of ways to store energy if you're basically getting it for free,
and these are generally more efficient at scale. It would be great if a
utility could help buffer this for you.

~~~
jakub_h
Yes, that's another reason why a municipal grid would be useful: city-wide
storage could work better than each house having a small battery (but the
roofs are still useful for panels, of course). But it may not need to be a
utility in the traditional sense (unless the US meaning of that word is
different from what I understand it to be). Just some local company with a
contract. Or a few of them.

~~~
astrodust
Here the power company was split up into a generation unit and a distribution
unit. What you're talking about is having a third type, a storage unit, to
help manage demand.

If you can pull power off the grid very cheaply, even get paid to "dispose" of
it, then later return it at a profit, you could arbitrage solar capacity.

------
paulsutter
The article assumes net metering, which is a huge subsidy for solar. Peak
solar generation causes low spot prices for power (see the California "duck
curve"[1], and the negative prices that Germany has on sunny days[2]. In Texas
wind can cause energy prices to go negative[3]).

The costs of storage must to be included for a fair comparison, so that power
can either be saved and used by the household, or provided back to the grid.
If provided back to the grid, the homeowner should get paid the spot price
like every other generator, not full residential rates.

[1]
[http://www.bloomberg.com/news/articles/2015-10-21/california...](http://www.bloomberg.com/news/articles/2015-10-21/california-
s-duck-curve-is-about-to-jolt-the-electricity-grid)

[2] [http://www.pv-magazine.com/news/details/beitrag/german-
renew...](http://www.pv-magazine.com/news/details/beitrag/german-renewables-
pushing-wholesale-electricity-further-into-negative-territory_100019141/)

[3] [http://cleantechnica.com/2015/10/01/texas-electricity-
prices...](http://cleantechnica.com/2015/10/01/texas-electricity-prices-going-
negative/)

~~~
notatoad
This comes up in every discussion about solar power, but it seems unfair to
me. Yes, solar is subsidized by a whole bunch of factors. But so is coal and
oil, because the suppliers of those power sources don't have to pay the full
cost of the damage their pollution causes.

A fair comparison should either include all subsidies, or none. Not just the
subsidies we are used to.

~~~
jkyle
The problem isn't the subsidies. The problem occurs when the proportion of
solar users increases such that the utility's margins become low enough to
threaten the minimum budget required to maintain the infrastructure.

If you want to subsidize solar users to bootstrap that market and as a general
social good, that's fine. But you have to structure it such that the utility
still recoups the cost of maintenance. If they're paying market instead of
spot, the paid price is not taking into account the cost of transfer and
storage to the utility.

~~~
mreiland
When we get to that point the answer is to let the local government take over
maintence, much like roads. Subsidize it with a tax.

------
lafay
I had a 6.7 kW solar system installed here in the Bay Area late last year, and
you can beat the costs stated in this article by quite a lot if you shop
around. The best bids I got were around $3.30/watt installed -- that's
$2.31/watt with the 30% federal tax credit figured in.

For my particular location, assuming a 25 year system lifespan, I calculate
LCOE of 5.6 cents/kWh. Way, way cheaper than PG&E. Even without the tax
credit, it's still a significant savings at 8 cents/kWh LCOE.

Of course this math only makes sense if you're reasonably sure you're going to
stay put for a significant portion of those 25 years.

~~~
tertius
Does this include storage?

~~~
lafay
No storage. This is a grid-tied system that exports power onto the grid during
times when I am a net producer, for which I get credited at retail rates.

~~~
Domenic_S
Retail rates? Are you sure? (PG&E?)

~~~
lafay
Yes, quite sure. However, the credits can only offset the "debits" from the
times when you are a net importer from the grid (night, cloudy, etc). PG&E
sends a once annual true-up statement where you pay for your excess annual kWh
(assuming consumed kWh > produced kWh). If you are net exporter on an annual
basis (produced kWh > consumed kWh) PG&E only pays wholesale rates for those
at ~$0.04/kWh. They used to pay nothing if you were a residential net annual
exporter, but after recent change in CA state law, they now have to actually
cut you a check.

------
LeifCarrotson
> Also, residential electric rates, on average about 12 cents per kilowatt-
> hour in in the U.S., are much higher than wholesale electric rates – the
> price utilities pay to power generators – which are usually less than 4
> cents per kilowatt-hour.

That 8 cent difference is mostly the cost of distribution and storage or
variable supply. Distribution from the roof to the home would be inexpensive,
but storage is not cheap. Asking utilities to accept solar energy input at
this flat rate in exchange for the variable supply and grid backup may work
for a small fraction of society, but it will hit a critical mass sooner or
later and become infeasible.

------
kelukelugames
Has this been shared on HN yet? You put in your address and Google tells you
how much you save by installing solar panels.

[https://www.google.com/get/sunroof#p=0](https://www.google.com/get/sunroof#p=0)

~~~
NDizzle
Cool site, thanks for sharing. I have never seen it.

According to that site a $20k install would pay itself off in 6 years. That is
compelling.

~~~
bnolsen
I live in colorado and it says i would lose money by going solar. Interesting
since at costco, etc the solar guys are pushing pretty hard. I've held off so
far because I think there's still room for dramatic improvement in solar panel
and battery technology in the next few years.

Also I seem to get a new roof every 5 or so years due to all the hailstorms we
get around here. I suspect solar panels don't like big hailstones very much
and I have no idea what would happen if both the roof and panels are damaged.
I doubt a roofing company is well equipped to handle the panels.

~~~
MSM
That's actually pretty surprising to me, I have only visited Colorado a few
times but I have always been very (pleasantly) surprised by the amount of
sunshine.

A quick look on Wikipedia says Denver has sunshine 70% of the time totaling
~3,100 hours a year. I'm from MI where we see sun about once a week so I'm out
of touch, but that seems like it should be more than enough to recoup costs.

Is the amount of sunshine in Denver significantly different from where you're
at, or is there something else I'm missing?

~~~
bnolsen
might be current cost of energy is low here. and yes we get tons of sunshine,
amazing amounts.

------
pilom
"Note that the total installed costs include the federal investment tax credit
and any local rebates and tax incentives."

$3.50/W is WAY higher than I paid per watt last year after the federal tax
rebate. I had 3.125kW installed on my roof for $2.16/W. Looking at the map,
Denver gets grid parity between $2.00 and $2.50 and that has exactly been my
experience with the panels.

------
lutorm
They conveniently omitted Hawaii from that map. Solar here is already cheaper
than the grid, even after the very high installation costs and even if you go
totally off-grid.

------
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------
amelius
If rooftop solar has a net positive efficiency, why aren't companies paying me
to put solar panels on my roof?

~~~
mikeash
It's easier and cheaper for a large company to just find a big plot of cheap
land and put the stuff up there. Same basic reason that nobody's offering to
pay you to grow vegetables in your yard, even though growing vegetables is a
profitable activity in general.

~~~
sremani
One advantage of Solar on rooftop, is reduction of transmission and
transmission losses, also local handling of the peak etc. Utilities love
Distrusted solar in limited numbers. They do not love the idea of everyone
getting on the bandwagon.

------
known
Never IMO

