Who's afraid of Solar PV? • Hacker News Board

Re: Who's afraid of Solar PV?

#41

Post by Daniel_Newby » Fri, Aug 24, 2012, 1:43 AM UTC

slapshot wrote: post #4

An interesting problem is highlighted on that graph: solar seems to be peaking around mid-day, but energy demand peaks at 5 - 7 pm when solar is pretty weak. The curves showing pre- and post-solar have almost identical peaks; solar hasn't yet successfully reduced peak load. (The California energy system posts a similar graph, with a similar shape: http://www.caiso.com/Pages/TodaysOutlook.aspx , made worse by the fact…

> The difficulty is that, unless storage gets dramatically better, ...

Refrigeration! Put all the air conditioners and refrigerators on timers. Run them hard during peak solar hours. Then turn them off during the evening peak. If that would make the buildings too cool, make ice and melt it later to chill the air. (Some event venues already do this to handle air conditioning ten thousand people during midday.)

Re: Who's afraid of Solar PV?

#42

Post by yessql » Fri, Aug 24, 2012, 1:44 AM UTC

The article doesn't focus much on spot pricing, which is really important in what is going to happen in the future. They showed a big drop in utility revenue during peak hours. This revenue used to be caused by high usage multiplied by really high prices. Now its high demand multiplied by moderate prices.

If solar adoption continues along the path described (which is inevitable at this point, considering steadily dropping solar PV equipment prices) then the midday spot price will continue to drop as well.

We'll find out some answers to the question, what do you do when the spot price of electricity approaches 0? Water desalination. Pump water uphill. Charge electric car batteries. Electrolysis to convert water to hydrogen, for later use in fuel cells or combustion engines.

We will certainly see some innovation in short term energy storage, since the price of electricity just before the late afternoon peak will be much lower.

Re: Who's afraid of Solar PV?

#43

Post by MikeCapone » Fri, Aug 24, 2012, 2:04 AM UTC

brc wrote: post #35

MikeCapone wrote: post #33

Earlier quoted context omitted.

Power plants aren't free, people pay for the service they provide. If you can replace them with less expensive batteries (especially since people will be ready to buy electric cars for their main benefit, which is transportation -- getting paid to lease you battery is a side benefit) to store cheap solar power, that's a good deal, not a subsidy.

>If you can replace them with less expensive batteries Agreed. And when that is the case, then this behaviour will appear at large and be taken up enthusiastically. At the moment this manifestly isn't the case (stored solar by batter cheaper than large-scale power), so any calls for it to happen is usually a disguised call to force it to happen by producing regulatory benefits to a small subset by driving up the cost…

Maybe I misread, but I think the OP pointed out that it could be done with today's technology, not that it could necessarily be done cost-effectively today. But batteries are improving and their costs are coming down, so it's certainly possible to predict that it'll be possible at some point in the not-too-distant future. When that happens, people will be compensated because it makes economic sense, not because they are subsidized into an un-economic activity (though that could happen too, but I don't think that's what was argued here).

Re: Who's afraid of Solar PV?

#44

Post by nl » Fri, Aug 24, 2012, 2:12 AM UTC

shirro wrote: post #38

greendestiny wrote: post #29

Earlier quoted context omitted.

As another South Australian I have to say this article makes me a little concerned about further price rises of mains power to make up for the shortfall. Although the long term benefits of Solar are amazing the short term situation for power infrastructure here could be a problem. *Edit: I can see a flatter usage profile should probably mean cheaper power, but still I think there is some justifiable paranoia in worry…

Another South Australian. Power is just the next thing to be disrupted by technology changes. I think we need smart meters and a more market driven approach to retail pricing. Peak electricity costs can go through the roof and people will respond by shifting their usage to alternatives or different times when there is less demand and prices are lower. Unfortunately there is no market transparency and we are paying fo…

Unfortunately, a more market driven approach to retail pricing is often very consumer-unfriendly because it means your bills will be very unpredictable.

Power prices vary dramatically during a day, and are often gamed by generators. Exposing retail customers to those swings directly is dangerous IMHO.

Having said that, there are many intermediate steps that help. For example, many power companies do partition prices by time of day, which makes a lot of sense[1].

In South Australia, ETSA is trialing "Direct load management", where they can shut off air conditioners for 30 minutes using smart meters when there is high demand, in return for much lower tariffs[2].

[1] http://www.savepower.nsw.gov.au/Portals/0/docs/news/Media071...

[2] http://www.etsautilities.com.au/centric/our_network/demand_m...

Re: Who's afraid of Solar PV?

#45

Post by uvdiv » Fri, Aug 24, 2012, 2:18 AM UTC

reitzensteinm wrote: post #12

slapshot wrote: post #4

An interesting problem is highlighted on that graph: solar seems to be peaking around mid-day, but energy demand peaks at 5 - 7 pm when solar is pretty weak. The curves showing pre- and post-solar have almost identical peaks; solar hasn't yet successfully reduced peak load. (The California energy system posts a similar graph, with a similar shape: http://www.caiso.com/Pages/TodaysOutlook.aspx , made worse by the fact…

We don't need any breakthroughs. Electric cars could handle the entire peak load with today's technology, the right incentives, and capital flowing in the right place. The peak load for South Australia was 1.8 gigawatts. There are 1,275,041 motor vehicles registered in SA. If you could get all of them turned into electric cars plugged into the grid, it would be a 1.4 kW power drain per vehicle, which is less than the…

The peak load for South Australia was 1.8 gigawatts.

No, that's the average load at a particular time of day. (Averaged over all days over two years). The peak is about twice that:

South Australia experienced a mild summer with only a few days exceeding 40°C. A relatively short heat wave occurred in late January 2011.

The maximum demand for the year was 3,433 MW, and occurred 4:30 PM (Australian Eastern Standard Time) Monday 31 January 2011 (at a temperature of 42.9°C). A higher maximum might have been expected if the same conditions had occurred later in the week, after an extended hot weather period.

http://www.aemo.com.au/~/media/Files/Other/planning/0400-003...

Re: Who's afraid of Solar PV?

#46

Post by pyoung » Fri, Aug 24, 2012, 2:42 AM UTC

jorgem wrote: post #21

maxerickson wrote: post #13

Earlier quoted context omitted.

I doubt it gets that ugly. The per gallon charge for municipal water in the East Bay is ~$0.005. People like flushing their toilets and taking showers, so conservation only eliminates so much.

I dunno. My water bills average $200/mo, for a single home (no pool, mostly drought resistent yard, etc). We're in an area with low density (out in the country). I pay about $120 in fees. Then the water is the rest of it. In winter, when we use less water, my bill goes down to about $130. $10 worth of water per month.

They may be charging you more per gallon in the summer. Also, rural municipalities need to charge higher fees and taxes per person to recoup their costs. This is due to the fact that they have to maintain a water system that serves a larger area but fewer people.

Re: Who's afraid of Solar PV?

#47

Post by reitzensteinm » Fri, Aug 24, 2012, 2:45 AM UTC

uvdiv wrote: post #45

reitzensteinm wrote: post #12

Earlier quoted context omitted.

We don't need any breakthroughs. Electric cars could handle the entire peak load with today's technology, the right incentives, and capital flowing in the right place. The peak load for South Australia was 1.8 gigawatts. There are 1,275,041 motor vehicles registered in SA. If you could get all of them turned into electric cars plugged into the grid, it would be a 1.4 kW power drain per vehicle, which is less than the…

The peak load for South Australia was 1.8 gigawatts. No, that's the average load at a particular time of day. (Averaged over all days over two years). The peak is about twice that: South Australia experienced a mild summer with only a few days exceeding 40°C. A relatively short heat wave occurred in late January 2011. The maximum demand for the year was 3,433 MW, and occurred 4:30 PM (Australian Eastern Standard Time…

Oops, my mistake - thanks for pointing that out!

That said, it actually makes my case significantly stronger. With 10% EVs and 20kW chargers, you can put 2.5 GW into the grid at peak, which is over 2/3 of the instantaneous maximum demand for the year.

I'd love to see figures on how much you could save providing a grid with 1.8 GW of base load vs having to engineer it to be able to handle nearly twice that, once a year.

You'd have to go to 15-20% EVs to support that, but if you're shutting down half your traditional power stations and investing heavily in solar, it may actually make sense with today's prices. Then again, lithium prices would skyrocket going to those kinds of extremes...

Re: Who's afraid of Solar PV?

#48

Post by caf » Fri, Aug 24, 2012, 3:10 AM UTC

reitzensteinm wrote: post #39

caf wrote: post #30

Earlier quoted context omitted.

So you want to subsidise the purchase of expensive cars to the point where it is financially a good deal. This magic money no doubt comes from other taxpayers. The proposal isn't a subsidy. It's a straight market payment for an economic benefit - the difference in cost between off-peak and peak electricity is real, and this means that storing off-peak electricity and releasing it at peak is an activity that's worth m…

Well, the benefit is that it combines the capital costs of owning a vehicle and storing energy. Many people will be purchasing a 160+ mile range car, but day to day use only 20-30 miles of that - an unused capacity large enough to power an average house for over 24 hours . This is in contrast to dedicated lithium ion batteries, which just don't work out economically. Otherwise you're right - the utilities would do it…

I can see how that's true if the car owner's continue to pay the capital costs of the battery - the part I'm taking issue with is where you say that it would likely that the car owners would have the capital cost of their battery packs paid for by taking part.

Re: Who's afraid of Solar PV?

#49

Post by nl » Fri, Aug 24, 2012, 3:14 AM UTC

comicjk wrote: post #14

slapshot wrote: post #4

An interesting problem is highlighted on that graph: solar seems to be peaking around mid-day, but energy demand peaks at 5 - 7 pm when solar is pretty weak. The curves showing pre- and post-solar have almost identical peaks; solar hasn't yet successfully reduced peak load. (The California energy system posts a similar graph, with a similar shape: http://www.caiso.com/Pages/TodaysOutlook.aspx , made worse by the fact…

Or just install twice the solar panels, if they're getting cheap enough. Or put them 4 time zones East (they will have to float in some cases) and send the electricity West.

Or put them 4 time zones East (they will have to float in some cases) and send the electricity West.

This is a good idea, except electricity transmission costs are significant over long distances like that.

Re: Who's afraid of Solar PV?

#50

Post by reitzensteinm » Fri, Aug 24, 2012, 3:26 AM UTC

caf wrote: post #48

reitzensteinm wrote: post #39

Earlier quoted context omitted.

Well, the benefit is that it combines the capital costs of owning a vehicle and storing energy. Many people will be purchasing a 160+ mile range car, but day to day use only 20-30 miles of that - an unused capacity large enough to power an average house for over 24 hours . This is in contrast to dedicated lithium ion batteries, which just don't work out economically. Otherwise you're right - the utilities would do it…

I can see how that's true if the car owner's continue to pay the capital costs of the battery - the part I'm taking issue with is where you say that it would likely that the car owners would have the capital cost of their battery packs paid for by taking part.

My back of the envelope calculations elsewhere in the thread were $1571/yr savings per car (10% overall reduction in grid cost); the Model S battery replacement insurance is $12k per car, which is a ~7.5 year payback (by which time, they claim the pack will be at 70% effectiveness).

Elsewhere someone corrected me that the peak grid usage in a year is actually significantly higher - the figures I was looking at were average daily figures - which may make grid savings quite a bit higher than 10%.

I don't think it necessarily is a clear financial win now; I'm just saying, if you squint just right it kind of makes sense now, and with the march of battery technology and PV, not to mention the inevitable adoption of EVs whether or not this scheme exists, it's going to look better and better from here on in.