It's Nearly Lights Out for PG&E's Solar Power Buybacks

PG&E will argue the viability of the power generated from solar makes it inefficient and costly to transmit - problem is they are right.

Solar cells generate electricity in the form of DC power. All utility electricity and the grid that connects them is AC power. The problem arises in the form of inverter used to transform the power to AC current. Commonly the use of high speed SCRs to produce an AC sign wave (AC current) also produces a capacitive effect on the current. Voltage lags 90deg. It also has been known to create non-sinsudal sign waves (harmonics) All these conditions creates problems from transmitting the AC power.

If commercial entities were encouraged to produce and use the solar electricity they produce then it would be viable. Imagine every store of the mall having solar cells and producing a large portion of their consumption.

But currently as it is we have a collection of very small facilities that purposefully over produce solar electricity with the explicit intent to force utility to purchase the excess power. The utility meter runs backwards - literally

A better prosal would be an amendment to Title 25. That is the amendment to the building code the State of California imposses on all commercial construction. "All commercial entities over 10,000 sq ft. shall provide solar cell electrical generation of a combined capacity equal to 60% of the FLA of existing HVAC (air conditioning equipment)

Important to note since you request the builders to provide it and businesses to use it won't meet much resistence.

At the same time Businesses which represent the majority of peak hour consumption of electricity will realise the profit - over the long term (2 to 5 year payback) This makes it an easy concept to sell

Modern grid tie systems are very good, and incidentally I know a whole lot about inverters being an EE, and the idea that the power from a modern inverter is overly reactive is bullcrap, unless of course you are driving them beyond their rated power and expecting too much from the capacitor bank. As to the harmonics, you have to have a pretty crappy inverter for them to be signifigant.

The circuit you are referring to is here:



http://www.freeinfosociety.com/electronics/schemview.php?id=1599

At this date anyone using the above to generate mains AC is a moron. Even the cheap $60 UPS units you buy at staples use a DSP-based inverter these days, likely even an IGBT one. These produce a true sinusiodal output regardless of load.



http://www.freescale.com/webapp/sps/site/application.jsp?nodeId=023Z1DxpCp8GVS

That's the cheapo kind. The "industrial strength" ones are even more finessed.

Glad to meet you skids

Since I have been working in Electrical Engineering myself specializing in Energy Management solutions since 1990, and Utility Generation since 2000, I would certainly like to see the consumer side of the equation change. Reluctantly they have not – they buy the cheaper, less efficient inverter. Every time guaranteed.

Had McPartland not written his article in 1993 disclaiming the notion of harmonics content, nonsinusoidal sine wave theory we might have made some advances in this area. Unfortunately he did and probably set the industry back 5 – 10 years.

Problem is you have with your solar cells is the efficiency.

Not that it can’t be fixed, or rectified as the case may be, but you’ll need to apply that on smaller scale consumer side applications if you wish to see the desired changes in the viability of solar power.

1994, UL threatened to pull its approval off Variable Frequency Drives. The reasoning was the high amounts of harmonic content generated from VFD use. 1996 most manufactures replied using improved circuitry. Inverter manufactures such as Liebold UPS systems went to static UPS with capacitive banks providing the ride through current.

1998 began the advent of VSD (Variable Speed Drives) Same old dirty circuits under a new name.

Just because you can build a better mouse trap doesn’t mean they will buy it. You’ll need to make it advantageous for them to buy it

BTW: example No. 2 is a gross polluter of nonsinusoidal sine waves (harmonic distortion) and yes the loading of nonsinusoidal sine waves is a logarithmic function. So a little loading goes a long ways to reduce the over all efficiency of the total power being transmitted

Oh ya, here are some pics from work for you - notice the solar panels in the back ground of pic No. 1

...but it seems to be all the rage. I'm of the mind that if I end up with a system, I'll be storing my excess for my own use, not selling it back at a discount.

The funny part is when I worked in Energy management engineering is we worked on a 6 month pay back scheme. Basically all the equipment we designed and installed paid it self off in 6 – 12 months. It does work, and it works well.

Total losses across the grid are probably in the area of 15% due to power factor at the end user in addition to the 15% lost in transmission. When you equate that 30% to the total pollution output of coal fired or Natural Gas fired plants nation wide it is an incredible amount.

Don’t get me wrong about solar – I’m all for it.

Just not the part about forcing the utilities through the PUC to pay for it. Which in the end those cost are passed back down to the consumer – you and me.

By mandating it through the Building codes you create 2 things, 1 the industry infrastructure to produce a quality product at an affordable price. 2 the end user using the energy produced from the solar cells (photo voltaic panels)

If wonderful Wally Mart (WalMart) is forced to supply 60% of the total air conditioning load in their building through photo voltaic load they are going to be concerned with the efficiency of the over all system, including the total load .pf (power factor applied to building load)

In no time at all equipment producers will meet these needs at a competitive price.

When it is YOUR power you are producing and using, you are more inclined to correct the power factor and clean up the harmonics.

...is that PV is hardly the most efficient way to use solar energy for HVAC. If you're a large flatbox building like WalMart and it's your HVAC costs you are looking to cut, you may as well pop for a dessiccant system and get the efficiency boost from collecting the whole solar spectrum (as heat, and without the expensive PV panels.)

For smaller (household) applications that might work, but only because nobody has bothered to scale down a dessiccant system into a window box.

for the big box stores. Sure central plants are a pain in the ass, but here in Southwest Arizona we can stick a heat exchanger in the cooling tower loop as a hydronic economizer and see some serious savings energy-wise. It wouldn't hurt if they paid more attention to building envelope design, although ASHRAE 90.1-2004 really bumps up the envelope efficiency requirements over previous versions (it just hasn't been adopted by any local jurisdictions yet).

We also use desiccant systems, but in a different way - they are part of ventilation air energy recovery systems.

Central plants are great for Supermarkets (food stores) Mall common zones, and large office complexes. Although food storage refrigeration doesn’t have the same humidity considerations on the evaporator side.

Not to mention the insurance industry would fight you because of the product loss clause most of the supermarkets must carry. If a Mom and Pop (privately owned supermarket) loses their meat refrigeration they are out of business.

We have done many many passive cooling projects with warehouses and we don’t use mechanical cooling at all. Just computer driven passive cooling schemes, and I must say they work quite well.

The problem is there is not the type of pressure needed in the design phase of construction to force the evolution of “Green” alternatives. As the discussion started out we were discussing the viability of Solar. But I’ve performed several projects of power factor correcting/efficiency savings at the 230 Kv source substation that have paid off in less then 6 months. And that included purchase of 1.2 million dollar substation.

There is a lot out there, but which is the best means to drive the industry.

Here in Arizona state-funded buildings must be LEED Silver certified. Something like three-quarters of the LEED points are mechanical design issues, but we've also managed to convince building owners to install solar as a way of gaining points. The problem is that the overhead for a LEED project is insane so we're not getting a lot of LEED projects from other clients. It also doesn't help that there isn't parity between LEED points. You can gain points by installing a central plant (and probably blowing your budget) or you can claim a point by adding a $300 bike rack - you tell me what a building owner is going to do.

My wife is an architect and I’m an engineer and we were just discussing this issue.

When back when Jimmy Carter and the Oil Embargo came along no one ever heard of these systems. Well except for a few wackos with those silicon crystals and some wacked out Thermo Dynamic thesis papers. With in 6 months of Carter implementing the federal tax incentives cottage industries sprung up all across America. Another 6 months later advancements in the technology was already cropping up every where you could see.

It’s scary to think of the advancement s we could have made in the last 25 years had it not been for Ronald Rayguns killing the tax incentives the moment he walked into office. Like a contract killer hired by the Oil monopoly of this country the technology advancements STOPED DEAD IN IT’S TRACKS by a political hack.

Will most of it any way. Some hanger on-ers like my self and a few others keep going running salesmen all over corporate America attempting to sell our wares. No real advancements were made. Will except maybe for a few.

You want to see advancements made in the technology you need to legislate the markets. The market drives the technology – always

Legislate the commercial entities produce a good percentage of what they consume and the market will drive the technology.

Desiccant systems are real great at removing excess moisture, and every mechanical engineer will readily admit you can’t begin to mechanically cool the air until you first remove the moisture.

Where that notion falls apart is you will run into too much resistance by business leaders and politicians claiming you are pushing unproven unreliable technology. Basically you’ll be taking on the manufacturing lobbyist who might outgun your efforts.

You need to crack the door open on these ideas and the best way to do that is mandate the construction methods and materials.

First thing we used to do for large projects was put in place the monitoring equipment. All LAN connected and producing tons of data logging tracking every watt, and every thermal degree inside and out. Then we would start selling the next phase. Now you are going to ask some facilities engineer to lay his career on the line for some questionable technology.

Sorry for playing the Devil’s advocate, but this has been my experience.

You also need to consider office building applications where they close for the weekends. Typically they are going to allow the temps to float up to 85 deg. Not to mention at night in all those buildings the humidity soars through the roof too. All the ambient temps come out at night. Those conditions are best offset by stored energy from solar panels driving evacuation blowers.

During the off days when offices are closed solar energy would then be used for passive cooling schemes.

The humidity-only desiccant systems are in fact in use on a fairly widespread basis, especially for grocers, and the absorption chillers are verging on commonplace. Studies abound on their hybrid use.

The point being both absorption and dessicant systems are fairly well established and "proven" -- adsorption is less so than absorption unfortunately. It's only their integration with a solar heat or preheat source that isn't, as they tend to be driven by natural gas or indirect fired from a boiler that's used for heat otherwise.

Really all the solar would be doing would be replacing the boiler in an indirect-fired setup.

Perhaps what's needed is a global campaign to get people to think of electricity as "high quality" power for which the heating and cooling tasks are not a worthy use. Though I guess in America that would be futile since our solution here to everything is "plug it into the wall." It's pathetically easy to get "just too complicated" for one of us these days I agree.

A better proposal would be an amendment to Title 25. That is the amendment to the building code the State of California imposes on all commercial construction.

"All commercial entities over 10,000 sq ft. shall provide Photo Voltaic generation of a combined capacity equal to 60% of the FLA of existing HVAC (air conditioning equipment) or 60% to total BTU of existing HVAC or Refrigeration equipment shall be derived from desiccant systems, or a combined total Photo Voltaic and desiccant system load equal to 60% of the total mechanical load”

Yes I’m all for that, but remember legislate the market and let the market drive the technology. Then perhaps we will begin to see some true advancement made in this technology. Personally I would like to see Thinfilm Coating photo voltaic

We have a municipal utility here in Sacramento (SMUD) and they offer more ecological power and better service at a lower price. Basics shouldn't be sold at a profit by a monopoly and PG&E is a great illustration of why.

Check post No. 5 Those are SMUD utilities.

The problem being when PG&E and other utilities came into existence the government required them to provide power to every one. Out in the remote areas as well as the big cities. The problem being the big cities are vastly more profitable then the remote country side.

So municipalities began to spring up in the metropolitan areas claiming eminent domain and taking over highly profitable areas of the total grid. Another problem is absolute power corrupts absolutely.

Big Fish – Little Pond mentality as these new managers did not have to answer to a board of directors and shared inside contacts with the PUC. Case and point – Rancho Seco Nuclear Plant. Never produced 1 watt of sellable power. Total cost to all power consumers of Northern California (PG&E customers and SMUD alike) over 900 Million dollars.

Then there are other technical problems rate payers PG&E and SMUD a like pay for but don’t even know it. If you understand the technology I’ll take the time to explain it.

I've been following along with interest. I'm an EE, but not in the power field. I do have an interest in PV, and have been using a small homebrew PV system for about 15 years on my home. I'd love to see more energy efficiency and use of alternate, clean fuels.

OTOH, I also have a couple of MBA's (Mgmt and Finance, from Golden Gate Univ) and I'm a PG&E stockholder. So I have a foot in both camps.

So please, carry on with the discussion. I'm listening. Thanks.