Chapter: kW DEMAND vs kWh consumption. How LEDs and solar PVs are rather ineffective

[ggunn]

It's not a two phase service.


Why do those homes have a three phase service?




The transformer doesn't get in the way as the road block.

1) There are two phases to the typical home and inverters connect to both of them, but I don't see what difference it makes if they are derived from a single phase of the distribution system. Residential solar exists to reduce the consumption by a residence, not to power the grid.

2) I have no idea but they exist. Not that it makes any difference. See 1).

3) So what is your point? What roadblock?

 

[Electric-Light]

1) There are two phases to the typical home and inverters connect to both of them, but I don't see what difference it makes if they are derived from a single phase of the distribution system. Residential solar exists to reduce the consumption by a residence, not to power the grid.

2) I have no idea but they exist. Not that it makes any difference. See 1).

3) So what is your point? What roadblock?

No there aren't, center tapped output isn't two phase.

 

[electrofelon]

No there aren't, center tapped output isn't two phase.

Well it really comes down to semantics since the primary of the transformer may be fed with who phases. Around here there isnt as much MGN distribution as delta distribution.

 

[Electric-Light]

Well it really comes down to semantics since the primary of the transformer may be fed with who phases. Around here there isnt as much MGN distribution as delta distribution.

I disagree. Splitting the phase with a center tap isn't adding a phase. Plugging in a transformer L-N into an outlet and creating 60-0-60 doesn't create a two phase power. For instance, you can't use a transformer to create a 3 wire service that provides 208v end to end, 120v neutral to either end from a 240v 2 wire source.

So, I think residential solar ends up being analogous to a hybrid boost that gets applied at the left wheel rather than in between the engine and the transmission, placing the burden on utility facilities to tolerate phase imbalance.

A true two phase 208/120 inverter would need to produce the second phase with a 1/3 cycle delay and three phase inverter would need a further phase source(0, 120 and 240 degrees)

 

[electrofelon]

I disagree. Splitting the phase with a center tap isn't adding a phase. Plugging in a transformer L-N into an outlet and creating 60-0-60 doesn't create a two phase power. For instance, you can't use a transformer to create a 3 wire service that provides 208v end to end, 120v neutral to either end from a 240v 2 wire source.

So, I think residential solar ends up being analogous to a hybrid boost that gets applied at the left wheel rather than in between the engine and the transmission, placing the burden on utility facilities to tolerate phase imbalance.

A true two phase 208/120 inverter would need to produce the second phase with a 1/3 cycle delay and three phase inverter would need a further phase source(0, 120 and 240 degrees)

A utility transformer that is connected line to line on the primary will send energy from the inverter to two of the three utility phases. why on earth does this matter anyway? Due to the randomness/mix of phase combinations used to supply single phase services I'm sure it all pretty much balances out. Large PV installations will typically be three phase.

 

[iwire]

I like the lower usage, however the money I spend on the lamp wipes out the value from the energy savings.

That seems to be an entirely self centered view.

There is a value to all of us on the planet to use less energy.

 

[iwire]

I disagree. Splitting the phase with a center tap isn't adding a phase. Plugging in a transformer L-N into an outlet and creating 60-0-60 doesn't create a two phase power. For instance, you can't use a transformer to create a 3 wire service that provides 208v end to end, 120v neutral to either end from a 240v 2 wire source.

So, I think residential solar ends up being analogous to a hybrid boost that gets applied at the left wheel rather than in between the engine and the transmission, placing the burden on utility facilities to tolerate phase imbalance.

A true two phase 208/120 inverter would need to produce the second phase with a 1/3 cycle delay and three phase inverter would need a further phase source(0, 120 and 240 degrees)

Help me out here, most home PV systems are not going to produce more than the home uses so it is not trying to boost into the grid it is simply lowering demand on the grid right?

 

[GoldDigger]

Help me out here, most home PV systems are not going to produce more than the home uses so it is not trying to boost into the grid it is simply lowering demand on the grid right?

Many home PV systems are sized to offset 80% or so of the annual energy consumption.
To do that using input energy only during the day, and peaking around solar noon, it will have to produce morecenergy than is used during the day to make up for the additional energyvused at night.
So, yes, most will feed back into the grid part of the day.

 

[iwire]

So, yes, most will feed back into the grid part of the day.

I do not believe 'most' home PV systems will. Most system sizes are limited by available space.

 

[ActionDave]

I do not believe 'most' home PV systems will. Most system sizes are limited by available space.

But most homes use a tiny amount of juice during the day. There are also projects called Solar Gardens where folks share the cost of a big array. Most Home owners involved in solar want to be energy producers.

 

[ggunn]

No there aren't, center tapped output isn't two phase.

I know how it works. My point was that most homes have 240V three wire power, and virtually all residential PV inverters connect to both L1 and L2. The fact that L1 and L2 are derived from the same phase of the distribution system is not relevant. In an area of high residential PV penetration there are systems on all phases so whatever imbalance results is minimal. In an area of low penetration, there aren't enough systems on line to make a significant difference. Commercial PV typically interconnects with all three phases at (most often) 480V or (less often) 208V. Utility scale PV always does, and usually at least at MV.

There are challenges in maintaining a grid with a lot of interconnected PV and/or wind, of course, but that doesn't make it not worth doing.

 

[ggunn]

I do not believe 'most' home PV systems will. Most system sizes are limited by available space.

Most residential PV backfeeds the grid occasionally, but the amount of that backfed energy is usually very small compared to the average load presented by the house, and is virtually always a net negative amount over a year's time. What that has to do with anything, I dunno.

 

[Electric-Light]

That seems to be an entirely self centered view.

There is a value to all of us on the planet to use less energy.

You know that that's not your honest belief :happyno:

On one end of the extreme,there's a colossal power plant serving the entire nation and on the other end, each house having its own generator. Somewhere in between is a good balance. I think a bunch of miniature 3-5 kW single phase, non reactive power capable, micro generators is too close to the latter extreme and causes more technical and administrative burden than they solve.

As it is administered now, solar PV is extremely financially inefficient due to excess amounts of money that vaporized in the multilevel sales network with the final layer of residential retail sales layer causing a huge expenditure in deploying the systems and as you can see, the biggest proponent is that particular layer of the sales network.

 

[iwire]

You know that that's not your honest belief :happyno:

Actully it is a fact not a belief.

As it is administered now, solar PV is extremely financially inefficient due to excess amounts of money that vaporized in the multilevel sales network with the final layer of residential retail sales layer causing a huge expenditure in deploying the systems and as you can see, the biggest proponent is that particular layer of the sales network.

Which is entirely typical of any new technology.

 

[ggunn]

As it is administered now, solar PV is extremely financially inefficient due to excess amounts of money that vaporized in the multilevel sales network with the final layer of residential retail sales layer causing a huge expenditure in deploying the systems and as you can see, the biggest proponent is that particular layer of the sales network.

I don't know what you mean by that. Residential solar is largely installed by PV integrators who buy their materials and supplies from wholesalers and install it themselves. It isn't any more "multilevel" than any other retail business.

 

[Electric-Light]

I don't know what you mean by that. Residential solar is largely installed by PV integrators who buy their materials and supplies from wholesalers and install it themselves. It isn't any more "multilevel" than any other retail business.

There are still too little panels moving at once and money changing hands too often.

Currently, solar has way too much retailing price inflation. The purchasing is not done the same way as say power meters or substation transformers.

Manufacturer -> importer -> distributor -> supply house -> installation integrators

The pricing could be much better if the federal government bargain with the manufacturers, then, pass over to the utilities who can arrange installation and use the best bid install guys that do not soak up the "mark up" that has to be absorbed by tax credits and rate payer fees.

The sales oriented marked is where solar incurs extreme expenses to the public. ARRA is the intent more so than the claimed energy benefits, but the problem is that excess amounts end up in installation dealer's who will try to maximize profit, hire as little as possible.

 

[ggunn]

There are still too little panels moving at once and money changing hands too often.

Currently, solar has way too much retailing price inflation. The purchasing is not done the same way as say power meters or substation transformers.

Manufacturer -> importer -> distributor -> supply house -> installation integrators

The pricing could be much better if the federal government bargain with the manufacturers, then, pass over to the utilities who can arrange installation and use the best bid install guys that do not soak up the "mark up" that has to be absorbed by tax credits and rate payer fees.

The sales oriented marked is where solar incurs extreme expenses to the public. ARRA is the intent more so than the claimed energy benefits, but the problem is that excess amounts end up in installation dealer's who will try to maximize profit, hire as little as possible.

Do you have any direct dealings with the solar industry? It doesn't sound like it to me. I have been in the solar business for nearly seven years. It is extremely competitive with very narrow margins. I know what modules sell for from the manufacturers and what the cost to the end user is. The massive inflation of the price of solar modules you speak of simply does not exist. In fact, the biggest increase in the street price of modules lately was due to government intervention, the solution you seem to be touting.

 

[Electric-Light]

Do you have any direct dealings with the solar industry? It doesn't sound like it to me. I have been in the solar business for nearly seven years. It is extremely competitive with very narrow margins.

It's a matter of allocation and itemization and billing method. T&M.. or flat?

I know what modules sell for from the manufacturers and what the cost to the end user is.

Are you talking about the one man Sales & Install shop or whatever the fancy title they use buy at the wholesale retailer in units of one single digit kW residential job per invoice or multi-freight train quantities negotiated for utility scale purchases?

The massive inflation of the price of solar modules you speak of simply does not exist. In fact, the biggest increase in the street price of modules lately was due to government intervention, the solution you seem to be touting.

Yeah, but I am talking about the difference in what solar install integrators charge (not what consumers "pay", grand total of all gubbermint payments too) vs what they pay to their supplier.

The excess price padding (including the LABOR cost charged.... whether or not explicitly itemized) is probably related to adding what the consumer will pay, then adding up the amount the public will bear through a form of legalized tax evasion permit. So, eliminating this "tax credit" and refusing any new applications of subsidized net metering BS would quickly put an end to the mess.

 

[ggunn]

It's a matter of allocation and itemization and billing method. T&M.. or flat?


Are you talking about the one man Sales & Install shop or whatever the fancy title they use buy at the wholesale retailer in units of one single digit kW residential job per invoice or multi-freight train quantities negotiated for utility scale purchases?

Neither. Most of my experience is with small to medium sized commercial PV designs. I know what the module cost per Watt is from the manufacturer in 100kW quantities and I know what the markups are. It's not much. I have colleagues who are on the residential side as well, though, and I can assure you that no one here is getting rich from exorbitant equipment markups or excessive labor charges. Again, I am in the business myself; I drive a '95 Buick with 200,000 miles on it and it's not because my Tesla is in the shop.

From where I sit it appears that you are just anti-solar and throw anything you can dredge up at it whether it has any basis in fact or not. I'm sorry you don't like the ITC but you are welcome to your opinion. I don't like the subsidies paid to the fossil fuels industries. At any rate, solar will survive the ITC expiration at the end of 2016.

 

[Bugman1400]

Neither. Most of my experience is with small to medium sized commercial PV designs. I know what the module cost per Watt is from the manufacturer in 100kW quantities and I know what the markups are. It's not much. I have colleagues who are on the residential side as well, though, and I can assure you that no one here is getting rich from exorbitant equipment markups or excessive labor charges. Again, I am in the business myself; I drive a '95 Buick with 200,000 miles on it and it's not because my Tesla is in the shop.

From where I sit it appears that you are just anti-solar and throw anything you can dredge up at it whether it has any basis in fact or not. I'm sorry you don't like the ITC but you are welcome to your opinion. I don't like the subsidies paid to the fossil fuels industries. At any rate, solar will survive the ITC expiration at the end of 2016.

Which fossil fuel subsidies are you referring to? I didn't know there were any for coal or gas. If there is, let me know, I tend to lose touch over the years.