Selling Power Back to the Power Company

Because they pay you wholesale and charge you retail....?

Bingo.

Here in California, they charge you a variable rate based on the time of day, between 11 and 34 cents per kWH, but buy back from consumers with solar / wind systems at 4-7 cents. I don't sell squat back to the power company, I run my AC at full bore all day in the sun when the solar panels are in full production, then come home to my ice box of a house and shut off the AC for the rest of the evening. I KNOW I am money ahead on that deal.

I worked in a utility that was fairly generous about this topic. We installed a 'net' meter. When using energy, the meter ran up. When generating, the meter when down. In theory, someone could indeed sell everything they generated back to the utility. The problem - they never generated more than they used. In fact, they never broke even. As far as the billing, for what they used we applied the standard price. I knew of Zero customers that had a net balance in their favor, so at a residential level, I don't know what we would have paid.

I suspect the situation would have been similar to what you mention. If a user got enough generation going to regularly produce, they would have fallen into our 'wholesale generation' market that we purchased from (we were distribution only).

Our rate was not variable. Why? Because we didn't invest in meters much, we used only ones all over the place, which the dials had to be read on. So we just charged the high rate all the time.

Not here where I live in Australia they don't.

I pay 25 cents per kWh for peak power, 14 cents for off peak, and all of my solar generation is passed through a meter and credited to me at 60 cents per kWh.

Wait... the most you are charged is 25 c /kWh and you get paid 60 c /kWh?

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Seems like people would be supplementing the amount they sell back to the power company with the cheaper power they can buy...maybe only on the cloudy days in hopes of avoiding generation in excess of rated output.

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What's to keep someone from doing that kind of thing?

The Australian government has paid roughly half of the cost to install the system and the suppliers know exactly what kW solar capacity you have.

The rules are that if you increase that figure, then your solar credits will be reduced to somewhere around 20 cents/kWh.

Whilst you could augment your credits with a bit of cheating as you suggest, the odds are that your average input would be way out of whack with that of other similar sized installations, and an inspector would likely come calling PDQ, and then you would probably get no credits after your release from where-ever they put you for committing fraud.

Makes sense.

Man what a windfall (really no need to fudge the numbers)

The government footed most of the bill, and then you get to sell the electricity to the utility at several times what they can sell it to you.

Is the program still ongoing? The government paid installation I mean.

They introduced the scheme to increase alternative power input, expecting around a million homes to get involved, but it blew right out of control and their budget was well and truly shot to pieces. The scheme, which gave RECs (Renewable Energy Credits - redeemable at about 50% of the cost of a 2.5kW array) on a reducing scale dependent on the size of the array (the larger the array, the smaller the REC per kW) has since been reduced as well as the credits which are now capped at just 20 cents/kWh.

For all of those who signed up before the cutback, retrospectivity was prohibited by the courts, and so we are guaranteed the 60 cents/kWh until December 2016, at which time I'm sure that things won't be as rosy, but most installations will have well and truly redeemed their cost by then.

Once that occurs, and if they fail to offer credit for solar input at least equal to what we draw from the grid, then removing the solar meter and allowing the installation to use its own available solar energy will be the way to go.

My 2.5kW system cost me about $5000 with the RECs and average credits are around $500 per quarter. My system has been in place for a little over 3 years and has already returned its initial capital outlay. With 3 years still to go at the guaranteed rate, that's better than 33.3% return per annum on the investment. I can't complain about that whatever happens later.

How enthusiastic are the power companies, and other ratepayers who do not qualify for the generous price differentials?

Gotta say that enthuiasm of consumers has diminished in proportion to the reduction of both the installation RECs and the input credit level.

There are a number of early advantages for the power suppliers.

One is that the co-generation means that much of the energy being consumed is produced locally and therefore reducing powerline currents and consequent transmission losses.

A second advantage is that as the bulk of solar input is occurring during the peak time of commercial use of grid power, any alternative input is of assistance in keeping generation capacity under control.

A third advantage is that the federal government pays the RECs and a large proportion of the input credits come from individual state governments.

Whilst the the private suppliers are inevitably charged something by government for these advantages, they appear to be happy with the situation in that they actively compete for the custom of those with solar capacity.

The reduction of the scheme occured simply because of the overwhelming takeup by both residential and commercial users that it became just too expensive for the governments to continue funding it.

It is not unusual to see whole streets where almost every dwelling has at least 6 panels on their roof, and many factories have 60 or so.

Add to the above the occurence of the usual situation where the moment that something is subsidised, commercial enterprises increase their prices to absorb that subsidy, and the cost blowout was inevitable.

There's zero return on your investment. And SE nailed why it doesn't make sense to sell all your homebrewed power to the power company.

Now, if they installed/paid for the generating capacity and upkeep and let me use it for my personal use, I'd gladly give them any excess.

"There's zero return on your investment. " ---------------------

hmmmm - looks like if I could produce electricity for my own use; some how keeping it frequency balanced to the grid; return on investment would be P*T*Price where (P*T) is the kilowatt hours produced and Price is the The Unit Price of Grid Energy.

Call it what ever; but it looks like money to me.

Fortunately for me my local utility lets you have a 1:1 return rate, they just let the meter spin backwards when you are generating more than you use, so that you can basically use them as an alternating current battery!

Granted you don't get paid for the KWH you send back but then you don't have to pay to get them returned later either.

let me just point out...they're going to charge you to prepare your monthly "bill" (think of it as a bookkeeping fee for tracking everything) and they charge a toll for you to transmit on their lines. not exactly a great business model, and you put up all the capital and maintenance on your end.

They pay you roughly wholesale for the time of day production. You pay retail for whenever use. Other than that, you are much better off using locally. Storing it drives your cost even further up.

So what kind of a Gizmo would I have to have so that I could frequency balance my power production from multiple small scale wind and solar sources; in order to use what I produce while still staying connected to the grid?

you need a UL1741 approved inverter and a dual meter to clock both consumed and generated, however you will have to be careful, as the utilities are now monitoring micro-generation units that are not UL 1741 AND IEEE519 compliant and they will disconnect you.

That's what grid tie inverters are for, but you need to be very careful when connecting them so that you don't introduce "Islanding" into the grid system.

Not for the unqualified to attempt

UL 1741.. study the spec.. it is designed just for that.

Mostly?

Live without it.

You do not have a multiple anything anyhow.

Where I am, there is a 10KW per year cap on any excess. Doesn't make it cost effective to put power back on the line. Till this changes.

?? Those units make no sense. And even if kWh, that makes no economic sense, except as an artificial (= sleazy) restriction.

This is what is happening. A batterie is not always the way it is handled.

My solar feeds into the grid and the offset is what I dont pay on my bill.

It all depends on the country you are in and what contract you have.

Keep in mind that the solution has to have a safety device that switches off your end when the grid is down. This will prevent accidents with power in case somebody has to touch a part of the grid and switched it off on the Company side!

We have options ranging from time of day tarrifs to full offset and anything in between.

We have also recently looked at a group that is utilising company standby generators to supply the grid at peak times. Essentially they are brokering the excess capacity that companies have on standby (or even completely idle) to the power companies. They provide fuel and the necessary connections and interface software for the system and any power we might use while they are running is free to us.

If there is grid interruption, the generator is still available for us to use.

Thanks for interesting relevant topic. But please do quote (cents) in currency referenced to the country. I presume this has all been US(A) Cents.

The figure sort of looks like typical US figures for electricity prices.

My further questions on selling power to the grid are:

1) What might be the typical minimum power in MW that the grid will accept from a small supplier?

2) What are the strict specs & requirements in the quality of the power the grid will accept.

3) How does one physically wire-up or hook up to the grid?

4) What are the hazard & Safety considerations?

5) How do they monitor the quantity of power that you supply.

6) Presumably you supply to the grid in AC, is this right?

1) The minimum for grid tie here is one megawatt.

2) Grid tie inverters sense the grid power and shut down within milliseconds of grid power failure. They synchronize phase and match the voltage of the grid. Strictly speaking UL 1741-2010, IEEE 1547-2003, IEEE 1547.1, ANSI/IEEE C62.41, FCC Part 15 A & B, NEC Article 690, and C22.2 No. 107.1-01, would apply, requiring ground fault, islanding, and DC reverse polarity protection.

3) A dedicated grid tie system will hook up like a typical service entrance, with the exception of the required AC fused external handle disconnect. The distinct difference being, electricity can potentially flow from either direction.

4) See #3. There are many hazards associated with photovoltaics. The 2013 fire codes include updates to help resolve dangers of fighting a fire on a structure covered with solar panels. All grid ties should be inspected. NEC, specifically section 690, must be adhered to. There are multiple means of disconnecting photovoltaic systems from the grid - the transformer, the meter, the AC disconnect, and the inverter. Special lableing is required for marking DC lines, distribution panels, the disconnect, and the arrays. Proper bonding is also critical.

5) This varies a great deal with localities, but here, to get a 9 cent (US) premium on the solar power generated, a separate service entrance and meter are used. This arrangement is of no use for emergency or backup power.

6) Most inverters are field programmable to provide 208, 240, or 277 volts AC. Some are 3 phase. Micro-inverters convert to AC at each individual solar panel.

Correction: 1) The minimum for grid tie here is one kilowatt.

As far as currency is concerned, the $AUS and $US are currently within 3% of each other so conversion factors not necessary for this conversation.

In answer to your questions,

1) Currently 10MW is the smallest they consider, however they have indicated future development to smaller (1MW) units int he near future.

2) The broker agrees to make the necessary modifications to the power interface, but basically it must be synchronous, smooth and at voltage.

3) The hook up involves modification to our switchroom for the necessary hardware and the instalation of necessary control switchgear.

4) The broker takes on the instalation, but our own electrical staff would need to be satisfied of safety, interlocks and so on the the relevant Australian codes/regulations.

5) I'm not sure. I presume that they would initially evaluate our generators for suitability before going further with the contract.

6) Yes our grid is AC.

As it turns out, our individual generators are too small and we did not progress with the evaluation, hence the vague portions of this response.

It is indicative however that there are organisations out there that are looking at alternatives to maintaining large centralised systems when as a community we already have siginificant untapped potential.

I don't have all the answers, but here is a fact you may want to consider. I have a friend who had an expensive solar system installed. Excess energy during the day was sold back to the power company and at night he used energy from the grid. The balance was initially in his favor and he received a check each month. However, with time, the checks got smaller and over a two year period the monthly balance was no longer in his favor, even though he continued to deliver the same amount of energy back to the grid. When he inquired to the power company they told him that the rate they pay for energy is dependent (in part) on how many people deliver energy to them and since more people are delivering energy, the payback per kWh is less.

Thanks Welderman.

This sounds like a route likely for countries new into this type of thing. In SA, where I am, it is likely that it may follow a similar pattern. Germany, on the other hand has been at it for a very long time and they have several laws in place that favour the renewable energy supplier. This is what makes solar an economically viable venture in Germany, despite the fact that there is relatively little sunshine. I suppose things do get better as the country gets more and more into this practice and when they eventually pass laws in favour of the renewable energy supplier. On top of it, the story varies from state to state in the USA. I thought California was the better ito this issue.

Another interesting issue is this: What about generating renewable energy and selling it to the neighbours or even bartering with energy? Could work well with farms or with people that have open land.

I did see the one link above for additional information. Information on building and setup primarily. Are there any other sites that y'all are familiar with that are long on information and short on hype, BS and scams?

Any help received from this distinguished crowd will be greatly appreciated.

So what exactly are you wanting to know more about?

As someone who has designed built and used home built GTI systems for some years now I can give a few tips and pointers on the reality of their practical implementation, use, and interaction with the utility grid to help separate the facts and reality from the BS and "what if worriers" scare tactics.

tcmtech,

Thanks for the reply. I am not sure if I actually know enough to ask an intelligent question. I need a little foundation in this new world of alternate power (at least new to me). While I am an engineer, my background is mechanical (so you will need to type slow).

What I am looking for, at this point, is where can I go for basic information that will help me build that foundation so I can have a better idea of what I don't know. So far my searches turn up a lot of sites, but it is hard to distinguish those who know what they are talking about from those that do not. Then there is the bunch who just want to sell their crap. If you could point me in the right direction, I am more than willing and able to do the research.

Did all that make sense?

Are you looking for the technical aspects, legal aspects, or some other info?

My search at this point is primarily technical. I'd like to answer questions like

+ DIY designs, feasibilty, economics, scalability, effectiveness

+ Equipment and components what you need vs. what you want vs. what to avoid

+ How to avoid outdated info, it all looks the same online to me.

To reiterate something I said before, I absolutely do wish to put in the necessary time learning, I just don't want to waste time reading junk if I can keep from it.

Thanks again!

The threads in the link I gave earlier contain a lot of tech info on the how and why aspect of making your own DIY GTI units.

All the stuff I have on those threads has came directly from my own work and experience in creating basic simple but safe and reliable GTI units for the hobby and experimental level.

As far as finding more tech info than what I have presented I doubt you will come across much. I did a load of online research during the making of my threads to see what the competition was so to speak and I really didn't find much at all.

One of the largest issues you will see with GTI inverter design is that most everyone thinks that they work the same as a typical power inverter you use with your vehicle and they need to be built on the same circuit topology and are not! They are two entirely different devices that do two entirely different functions.

Legalities wise I am not the one to talk too.

If batteries will be completely out of the picture, where do you plan to draw power from for your own personal needs when and while there is some power outages and no sun light available like during night time?

A small generator running for a limited time to cover rare occasions like that would be far far more cost effective than investing in a complete set of batteries for a grid tie system just for those time power goes out at night.

Battery systems are not cheap, and if someone decides to go with a grid tied system, there are many better ways to invest funds than a backup battery banks that will require regular attention and hardly ever get used.

'...Sorry I did not realize until you responded that the OP and you are one and the same entity!....'

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Well, no reason for you to feel late to the party. In fact I'm fairly confident you are the first and will likely continue to be the only one coming to that particular 'realization' (it is highly unlikely that anyone else will err in just the right way to 'realize' the exact same thing which is so poorly correlated with real reality.)

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On a somewhat related note, here is an example of a conclusion at which sound minds given sufficient information are very likely to arrive:

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One need not be the prospective purchaser or even poser of the question to clearly see that for the typical residential application, spending the large amount necessary to purchase, install, and maintain a battery system, just as a backup for a grid-tie system (for those special occasions the power goes out and the sun is not shining), is clearly an inefficient use of capital.

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You don't need to be the OP to realize that for those couple hours a small generator can do a great job at a far cheaper price.....and if you are somewhere the power goes out all the time, then you might want to reconsider grid tie in the first place.

Since 3 years I am a pirate of the Caribbean.

Power costs here 21 cents + 23 cents oil surcharge making it 44 cents per kWh.

With 5000 watts installed and grid tie system(s) I can run with 0 power bill but keep it between 18 and 25 dollars per month. I just have to monitor when the meter reading guy shows up to ot make him dizzy with the way the meter spins backwards.

However, the power company has rejected all grid tie business and worse, are replacing the existing meter with a more pirate meter that only adds power.

The part you generate and passes the meter ADDS on too.

1 kWh consumption and 2 kWh own generation bills you 3 kWh.

The reason they come up with is linesman's safety. A big lie.

The only green in their home site is the love for the green buck.

The meter is a C1S with digital LCD display - beware!!!!

They go further and want to approve or reject all type of inverters and decide on what to run on solar.

So outback with the combined systems is a no go too.

We need to wait for a court decision that outlaws the use of that meter. If they do not want a grid tie, that they stop it at their own expense!!!

Maybe a 2" check valve will do the work or maybe not. LOL

In the meantime, you run whatever on your property as you wish, as long as you do not try backfeeding. Obviously, without the necessary agreement framework that won't happen.

A solar grid tie interface is superior compared to battery storage because it avoids losses in efficiency and mitigates peak demand. But it only works if power companies stop punishing people for generating their own power. Solar electric is a great investment. Otherwise the power companies would not be putting in ten times the amount allocated for customers. Check out http://www.dsireusa.org/ for any incentives that might be available in your state.

I looked into a system for a moderate boat. We design and build electric propulsion systems for boats since 1892. Looked into solar since everyone asks how can I power from solar. You can't. A 900 watt system requires 70 sq ft of space. Most boats do not have this space. So, curious, I looked into a 10KWH/d system. 44 panels, 44 charge controllers, mountains of wiring and if you can't tract the sun you lose way too much real usable light. How do you set up 44 panels that measure 39" x 65" on a tracking system to gain as much light as possible, store the power in batteries then invert this power to 60Hz 240V 1 Ph. This 10KWH system is $18K Payback forgetaboutit. Living off the grid, priceless. More like homeless after you buy everything you need to set up a system to capture all wind power and sun power. By the time you are done with all the systems to live off the grid and live the way we do it will be $40K and no payback in my life time. And I don't have that much left anyways. I retire in a few years. We need another power source than mother earth.

As I predicted in a previous & similar thread, the UK power companies have re-introduced standing charges in order to claw back revenue from those selling power back to them from their PV installations.