# Solar and Peak Power



## mbcijim (Jun 8, 2011)

PJM manages the grid in the NY-PA-NJ and some of the other areas, but not entirely sure.  Managing the grid means that they tell power plants to turn on (or off) as needed.  If we are using 800MW, they make sure 800MW is being fed into the grid.  

The guy who installed my solar system also has a very large company that is the interface between PJM and large power users.  That means that if your power plant uses 5WM of power an hour, PJM may turn off your grid power and you start using your generator.  A prison is a pretty good example.  A local prison has a load of 5MW.  However, they also have a generator should the power go out, I guess cause they don't want the prisoners to escape.  So when the grid is using all the power we are capable of producing, PJM shuts off the prison, and the prison turns on their generator.  It's an agreement everyone enters into at will.  The prison gets paid a pretty hefty fee (I think $50k/year) for them to be on standby, plus all fuel costs consumed for turning on the generator.

Today is supposed to be one of those days.  More power is foretasted to be used than we have power plants capable of producing - i.e. supply exceeds demand.  It only happens for 3 reasons:  really, really hot, really, really cold, or too many power plants are shut down.  So PJM is busy turning people off.  

This is really important to the solar industry.  Today we have one of those days (it's too hot).  But that also means that although I see blue sky outside my window, panel production is down 30% because it's TOO hot.  So while the power is useful, it's not as useful as it could be.  Production is down 30% and Pennsylvania now has 71MW installed.  So instead of producing 71MW of power it's probably more like 50MW when we really need it the most.  That's a 20 MW gas turbine that has to be built and sit in a room until days like today.  So if we want to talk about the cost of solar power we need to add this to the cost.


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## dougstove (Jun 9, 2011)

Or, we have to start dynamically managing many of the smaller loads, as well as big institutional loads.
With a smarter grid alot could be done to switch on and off discretionary power uses in accordance with supply.
But as you say, smarter grid management will cost money.


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## mbcijim (Jun 9, 2011)

I just signed up for a program with PPL (our regional electric distribution company).  They are going to give me a $72/year credit to turn off my heat pump on days like yesterday (and today) 50% of the time.  Off for 1/2 hour, back on for 1/2 hour.  

Commercially I own at least 1,000 tons of roof top AC (could be several thousand more, I just don't know).  As soon as they offer it commercially I'm signing up.  They do all the work, meaning PPL comes to my units and installs a device to control it.


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## DaveH9 (Jun 9, 2011)

PV s peak shaving ability is one of the reasons there are rebates. It costs the ratepayers for the rebates but then the smaller overall peak demand saves the ratepayers. Once there is a smart grid,and every one is paying the actual cost of the power at the time they use it, PV won't need rebates anymore. Time of use rates are usually good for PV owners depending on the off/on  peak rates and usage pattern. When the PV industry first started to lay modules on commercial building flat or at 15 degrees,  I wondered why they would take an efficiency hit by not tilting. Turns out that the summer peak is the most valuable time to make solar electricity. Adding tilting costs and wind load issues just did not make financial sense.


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## mbcijim (Jun 9, 2011)

Pretty cool stuff going on:

"As of 03:30 hours, a Maximum Emergency Generation Alert has been issued for 06/09/11 Maximum Emergency Generation has been called into the operating capacity. Additional Comments: Mid Atlantic load estimate 58,043MW, Mid Atlantic Operating Reserve Objective 4120MW, Mid Atlantic Estimated Operating Reserves 773MW."

The guy doing this basically told me that it means demand exceeds supply total by 4,120 -773 ~ 3,350 MW or 3 big power plants.

It's all public information.  Check out, and click on load at the top.  
https://edata2007.pjm.com/eData/index.html

IF they call for a curtailment, the top of the curve will flatten.  Peak power is predicted from 3:30-5:30 PM in the mid-Atlantic region.  Spot market prices have already hit .39/KW in the Dayton, Ohio area (chart on the left).  This morning they were at $.25/KW.  Prices will keep going UP today.  

Also, our part of the world averages 4.2 hours of sunlight a day.  Do you really think DaveH9 those hours are from 3:30-5:30 PM?  I don't.  That debunks your theory on the reason for the subsidies.  
http://www.solarpanelsplus.com/solar-panels/large-insolation-map.html

My system is really close to being available online within the next week or two then we can look at some real data in real time!


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## DaveH9 (Jun 9, 2011)

mbcijim said:
			
		

> Pretty cool stuff going on:
> 
> "
> Also, our part of the world averages 4.2 hours of sunlight a day.  Do you really think DaveH9 those hours are from 3:30-5:30 PM?  I don't.  That debunks your theory on the reason for the subsidies.
> ...



Yes I do think PV is peak shaving today. 4.2 hrs is the average per day, in the summer it's longer.  It's really not my theory,  it is the belief of many in the industry and regulative branches. 

3 to 5 is a time when commercial AC is humming, people are getting home to turn on AC, and it's the hottest time of the day. If someone wants to capture that time to get the most from a time of use or smart grid type rate structure the PV system would need to be facing SW to W at about 20 degree tilt.


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## mbcijim (Jun 10, 2011)

Here's an actual system in Pennsylvania.  Real time info.  

http://www.solrenview.com/cgi-bin/CGIhandler.cgi?&sort=pvi_IDs&cond=site_ID=635

Click on Revenue Grade, Change the day to yesterday (6/9/11), Click on Go.  You'll see that the 200KW system was producing 180KW around lunch but basically down to 40KW around 4:00PM and basically shut down by 5:00PM.

So when the peak hit at 3:30 yesterday, it was 35% operational, and by the end of the peak it was worthless.


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## corrupt (Jun 11, 2011)

Thats up to us to get smarter with our install directions. In Australia they recommend facing you system north at around 25deg, This is perfect to get the most kwh (whish equalls most $$) over 12months for the house holder.
 Really everyone should be getting a fixed amount of money for having a pv system fitted and then the goverment  adjust the direction of each system to adverage out the mass out put over a full day. so you face just under a 1/3 of the total systems fitted east to take the morning loads, just over a 1/3 west to take the higher loads when everone gets home in the after noon, and the other 1/3 north to get a steady input through out the whole year. Ideally we would all have trackers and everthing would be perfect.


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## Don2222 (Jun 13, 2011)

mbcijim said:
			
		

> PJM manages the grid in the NY-PA-NJ and some of the other areas, but not entirely sure.  Managing the grid means that they tell power plants to turn on (or off) as needed.  If we are using 800MW, they make sure 800MW is being fed into the grid.
> 
> The guy who installed my solar system also has a very large company that is the interface between PJM and large power users.  That means that if your power plant uses 5WM of power an hour, PJM may turn off your grid power and you start using your generator.  A prison is a pretty good example.  A local prison has a load of 5MW.  However, they also have a generator should the power go out, I guess cause they don't want the prisoners to escape.  So when the grid is using all the power we are capable of producing, PJM shuts off the prison, and the prison turns on their generator.  It's an agreement everyone enters into at will.  The prison gets paid a pretty hefty fee (I think $50k/year) for them to be on standby, plus all fuel costs consumed for turning on the generator.
> 
> ...



Yes, I agree. Also seems like the Prison will never be able to run on Solar because of all the power they use!!

I Wonder if the Electric Chair can run on Solar Panels???  Certainly would not work on a very Hot Day


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## mbcijim (Jun 13, 2011)

I thought about this over the weekend.  Pennsylvania has 71 MW of solar installed.  We had a peak two hours last week, and by 5:30, the very end of the peak, solar was 95% shut down.  So now, instead of having 71 MW (or 51 MW) contributing like we did at 3:30, the start of the peak, solar was contributing nothing when it was needed the most.  

So, what we can now say is MW per MW we need to also build a quick reaction power plant that can turn on as solar shuts down.  If we build 1,000MW of solar then we need to build 1,000MW of something quick reacting.  This all gets built into your electric rates so this is very important.  Electric consumers pay for that plant no matter what.  I assume the only thing able to turn on that quickly is natural gas or diesel?  What about coal or nuclear?  

Are we better off building the solar systems for the peak hour, which is 3:30 to 5:30 and angle the system accordingly?  Is it even capable of producing power at 5:30 on June 21st or is the sun just too low?

The death of solar power on utility scale is certain without technological breakthroughs, it's just too expensive.  Questions like this need to be addressed if solar is to have a future.


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## peakbagger (Jun 13, 2011)

Most simple cycle gas turbine power plants (peakers) can be at full load in five minutes from when the start button is pushed. Some of the larger combined cycle plants can come up to 2/3rds load fairly quickly but its hard on the heat recovery steam generators. GE builds peakers up to 100 MW. The biggest hassle is getting fuel for them as the gas utilities need some advance notice. Many of the plants have a big tank of jet fuel and run the peakers on jet fuel (not cheap).   The state of texas has built a large number of peakers to back up when the wind isnt blowing.


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