My Solar Panel Power Project

[eepete]

Solar Power Thoughts, Part 2:


Now lets think about a day where the temperatures are in the 95 to 105 degree range. This is when the electric utilities are at a maximum load. In fact, many utilities on these sorts of days will do two things to get more power. They will try to get power over the grid from areas where it is not so hot, and they will bring power generating units called Peaking Plants on line.
There is only so much power that you can get through the grid. There are both losses sending power over transmission lines, and limits as to how much power you can send over these lines. The power has to come from a near by part of the country where it is not so hot. That might be due to the time of day, it might be taking power from more northern (and hence cooler) areas, and it might be because some area has cloud cover. But we have also seen times when, for example, the entire U.S. east of the Mississippi had temperatures over 90 degrees from Miami to Maine. Increasing the grid capacity is very expensive. A high voltage transmission line can end up costing about $1 million per tower. It takes years to put one in since no one wants one near them (NIMBY).
Peak plants are small generating facilities that can produce between 50 and 200 Megawatts. Their electricity has the highest cost of production. A typical coal or nuclear plant produces 1200 Megawatts. These plants cost between 3 and 5 billion dollars. Often peaking plants are run by jet turbines (aka aircraft engines). A single engine on a 747 can produce 50 megawatts of power when it connects to a generator. These plants can be brought on line very quickly and their power output changed very quickly. They burn jet fuel or natural gas or diesel. They also cost $50 million to put one 50 megawatt unit in place. This is a hard number to exactly track down so if anyone has a better number let me know. There are many NIMBY problems with siting these plants as well as fuel supply logistics.

So lets look at the stage we have set with the above assumptions. We have a typical house one a very hot day. The air conditioner or heat pump is running about 65% of the time drawing one killowatt. When every gets home from work, they will bump the temperatures down and draw 1800 watts. The utility distribution grids are maxed out, and lots of jet fuel is being burned to add more power to the electric grid.

Now what happens if half of the houses have the 2 KW solar panels on them? Well, a house with solar panels that is running its air conditioning will use 1 KW and export 800 watts out for the house next to it that does not have panels. That house needs 1KW. But both are running at about a 65% duty cycle, so the net result is that all the residential cooling demand in an area is met by the solar panels with a little bit left over. Now the businesses still need power, but the demand on the electric grid is much lower. The peaking plants do not have to run, the PV systems make the peak power. The distribution grid has the ability to distribute energy and not be overloaded since the power is added all over the grid, right where it is needed.

 

[eepete]

Solar Power Thoughts, part 3:


So what does a 2 KW solar system cost? Well, today the cost of the parts is around $10,000. Installers tend to double the cost of the hardware so it would cost $20,000 to have it installed. Now imagine a _lot_ of houses having these systems, leading to volume in the millions of systems. A lot would be come standardized. The installed cost of these systems could be about $10,000 or $5 per watt.

Here is where it gets crazy. Imagine 20 million systems installed on houses at a latitude of 40 degrees or less. This is a line at the bottom of Pennsylvania, the middle of Indiana, the border between Kansas and Nebraska and the middle of Utah. You would probably have about 50 percent between the Mississippi and the Atlantic ocean, 20 percent in the west, and 30 percent in California. Now lets look at the East Coast on a hot day. You would have 10 million houses putting out say 1500 watts each (allow for differences in the angle of the sun, panels aging, and other things that would have the system not quite at peak capacity.

Thats a total capacity of 15 gigawatts of power. That is 12 big power plants, or 300 peaking plants. The cost of those big power plants is about 45 to 60 billion. The cost of the peaking plants is about 15 billion but the fuel they burn is more expensive and most of it is imported. The cost of new transmission lines is avoided, and that might run about 40 billion to upgrade the entire east coast. So the solar panels replace between 85 to 100 billion dollars worth of costs. Those panels will cost 100 billion dollars.

Repeat this exercise on the west coast.

So $200 billion means all of our summer peak power problems go away. We do not have to substantially improve the distribution grid and can focus on smarter improvements to the grid not just raw power capacity. We stop burning imported petroleum in a fixed point of use situation, which helps on pollution and takes some of the pressure off of fuel prices. There are lots of jobs created installing and maintaining these systems.

 

[eepete]

Solar parts, part 4 (and the last one):


There is a problem with how to finance all this. In a working world, the extra $10,000 would be part of a mortgage. You might even go to a 35 year mortgage to get the panels and improve the insulation in a house. Two problems here. Most people value granite counter tops and stainless steel appliances over energy efficiency. The second problem is that as we致e seen by recent events, the mortgage industry is somewhere between dysfunctional and run by clowns.

So why is it we can give the clowns $200 billion but not take that same money to solve energy problems and create jobs?

There are a lot of number and assumptions here. Lies, Dam Lies (we can solve our energy problem by just building more hydro plants), and statistics. Depending on what point of view you think is right, you can cook the numbers. So if anyone has better numbers than I show here, let me know and I will update this document. Note also I have not dealt with the cost of power, just kilowatt capacities and cost of plants. As the cost of power goes up, and as more parts of the U.S. go to time of day or peak billing, the economic feasibility of solar panels gets better. I have also not attempted to deal with indirect cost such as pollution, effects of more transmission lines (both real and NIMBY subjective), indirect cost of fuels both to create and then store waste products, health cost from pollution and the like. While natural gas looks good, there is a hidden cost of pollution due to the rock fracturing process. I have also not touched on global warming since that tends to stop all thinking on all sides faster than touching on religion.

Federal subsidies could encourage systems built with 65% US manufactured content. That and a commitment to this sort of volume would go a long ways to solving a lot of problems, both energy and loss of industry in the U.S.

I do think that if you deal with this in purely capitalistic cost terms, it will never happen because hidden costs don not count in capitalism. PV solar cost three to six times what coal cost. But if your peak power rate is three times the night time rate, then the peak cost of solar isn not far off the mark. I think if you view this more as a go to the moon or We must have a strong defense point of view, then the numbers are close enough that such a program could move forward with the realization that dealing with this now will be somehow better than ignoring it and waiting for a crisis. In the 70s we saw heating oil prices go up by a factor of 10. After Hurricane Katrina gas prices doubled. We are all living on the edge because it is the cheapest and we are moments away from game changing energy costs. There will hidden benefits that we can not even predict to this. Let me get off my soapbox now, and lets see where the discussion goes if we focus on the numbers - and more importantly the thoughts- I have used here today.

All I want is for people to think about if solar has a place in the U.S. If people reading this think there is no way it will ever be part of a solution, then that is OK and I thank the reader for taking time to think. It is the first step in solving any problem.



Pete

 

[roamerr]

I like that 4 point write-up. It has merit. My view is that the more systems that are installed the lower the cost will be in the future. Everytime a system is installed I smile cuz I know eventually I might be able to afford one.

 

[teg]

Looking into it at the farm... thanks for the write-up :thumbsup:

 

[eepete]

I've looked into it and the cost just doesn't justify doing it for me. I really do like the idea of not having to pay for power. But Vermont isn't one of the sunny states so that pushes out the ROI time. Does your state have a special price the utility must pay you for the power or do they just give you wholesale price. I don't know for sure but I've been told the new digital meters track both in coming and returning power independently so they know how much you've supplied.

Al, I have a digital meter that records both forward and reverse power. I pay for forward and get paid for reverse. North Carolina has a net metering law, so for grid tie systems you can get what you pay for power, but if you over-supply they will not cut you a check. So you pay for the net amount of KWH you use, but they won't cut you a check.

The power is being purchased by NC Green Power. They have a web site. Basically, they pay more than what the utility would under net metering. They get their power from people who wish to pay a bit more to purchase green power. If you have over 10KW (in NC) you are classified as a power generator and you get paid the burden rate for your power. So the rates are:

Burdon Rate: about 6 cents
My rate at he house for power I use: about 10 cents
What I get for my green power: about 15 cents.

I had to get a new meter and drop because the house if 400 amp service, and the meter base does not have CTs (current transformers). My power co-operative did not have a digital two way meter that would plug in. On the plus side, I've got an extra 100+ amps of service by the outbuilding garage if I need it.

Pete

 

[eepete]

Aside from why you did this in the first place - did you look at tracking systems instead of the fixed array and if so what swayed you to the fixed system?

Once I get the data logging up and running, I'll get some idea of what the penalty is for off angle usage. Then I can figure out what kind of cost for a tracking system would pay off down the road. So fixed and simple for now, it's what a lot of houses would have. Then, figure out all the costs of a tracking system by looking at how this system performs.

Pete

 

[CinderSchnauzer]

You might find this site to be of interest.

microFIT Program

 

[eepete]

CinderSchnauzer, very interesting and good numbers for tracking vs. non tracking efficiencies. If we had that program down here, there's a good chance I would have gone tracking. If the tracking payback was 58 cents per KWH, there's no question I would have done tracking. A 46% increase in capacity is pretty impressive!

The mounting rails are about $1K in costs. The stainless steel hardware and concrete cost are about $1200 in costs, but could be used to hold other types of mounts.

It's pretty interestin to see how the various buy back programs affect what's being done. The NC Green Power set a maximum buy back amount based on my DC power rating of 7.77 KW. I'd be over that maximum with a tracking system. Maybee what's going on in Ontario will spread to other areas as the advantages of tracking catch on.

Thanks for the link :thumbsup:.

Pete

 

[tommu56]

Pete
I looked in to tracking for my system (off grid on roof of mt cabin).
for the expense of hardware for automatic and hazard to change it manually I decided to add an extra panel or 2 if necessary and forget about adjusting it.

But for our cabin we haven't had any problems with 600 watts (made space for 1200 watts) and 1560 ah of battery's

tom