Utility payouts per KWH

adam1984

Can someone give me a general idea of how much utility companies pay per kwh for putting energy back into the grid? I understand it changes based on utility companies and obviously locations. Just wanted a ball park. Is .02/kwh good? Is it more like .20/kwh? Or way higher? Preferably NY and FL but all experiences will help. Thanks guys.

Cariboocoot

Re: Utility payouts per KWH

Ask your local utility; theirs is the only number that matters. Not every one buys back electric, even if they allow grid-tie. It's a funny ol' world.

If they'd pay $0.50/kW/hr you could possibly break even.

BB.

Re: Utility payouts per KWH

In Northern California, Grid Tied simply turns the meter backwards. Depending on your rate plan, it can range from $0.09 per kWhr -$0.65 (my E-6 off peak <300 kWhr per month, baseline tier, seasonal time of use residential--TO--summer peak >600 kWhrs per month).

The new smart meter plans can be as high as $0.70 per kWhr (summer 2pm-7pm in summer with 24 hour notice).

For me, realistically, (I use less than 250 kWhrs per month without GT solar)--so I am at the bottom of the rate tiers (use more power, pay upwards of 5x more for electricity), I "buy" off peak power at $0.09 per kWHr and sell summer peak power at $0.31 per kWhr.

At the end of the month, I pay a $5 minimum charges and they "balance" my account. For excess power I generated per month, I get paid ~$0.31 per kWhr, and for excess power I use I pay ~$0.09 per kWhr. All that goes into my "account balance". At the end of 1 year, I either pay the amount (if I used more power) or if there is a credit (I generated more power), the credit is set to zero.

Regarding costs--our utility, roughly, sets the billing up so that 1/2 of the retail cost is generation costs, and the other 1/2 is mostly local distribution charges (poles, wires, transformers, etc.)--and a bit to long distance transmission charges.

-Bill

Note: PG&E tariff schedules:

• E-1 Flat Rate Residential
• E-6 Time of Use for New Grid Tied Solar
• E-7 Time of Use for older Grid Tied Solar

-Bill

Ralph Day

Re: Utility payouts per KWH

In Ontario Canada a feed in tariff of $.802 is available for 10kw and under. There's little else as far as incentives go...the subsidy is in the 20 year contract price of 80.2 cents. My install is: concrete pad and inverters (enphase) in the basement. This week temps of -20deg C preclude any outside work! Racking is being made, panels are on the way from China (I hope). Just waiting for warmer weather.

Looking forward to watching the sun shine and the bank account grow. Base prices for 10kw systems run between $75-80K, less if you're doing some of the work yourself.

Ralph

peakbagger

Re: Utility payouts per KWH

the easiest way to find out is to search for the DESIREUSA.org website, its lists incentives for the all states and most local utilities.

LucMan

Re: Utility payouts per KWH

My utility in NY this month is paying 4 cents per KWH. The payout rate is whatever the wholesale electric rate for the month is which changes monthly.
I pay $.10 KWH plus another $.10 KWH delivery charges for a total of $.20KWH.
Credits are carried over monthly until the anniversary date of net meter installation.
That's when account is reset and they payout for any credits.

tallgirl

Re: Utility payouts per KWH

Ralph Day wrote: »

Looking forward to watching the sun shine and the bank account grow. Base prices for 10kw systems run between $75-80K, less if you're doing some of the work yourself.

I work with an installer who'd bid around $65K for a 10KW system -- less without batteries, more with batteries.

tallgirl

Re: Utility payouts per KWH

peakbagger wrote: »

the easiest way to find out is to search for the DESIREUSA.org website, its lists incentives for the all states and most local utilities.

This is why battery-based systems are better -- I'll be darned if I'm going to pay $0.145 / kwh (what I pay Green Mountain) when I buy back the same KWH's I sold for $0.075 / kwh (what TXU Energy pays).

i made that 'darned'. niel

russ

Re: Utility payouts per KWH

@tallgirl - You already are when you take the hit on efficiency.

TnAndy

Re: Utility payouts per KWH

TVA pays 12 cents over retail (floats with retail), which is about 9 cents thru our distributor....so I'm getting 21 cents currently for all solar production. 10 year contract.

Ralph Day

Re: Utility payouts per KWH

Julie,
The dollars in Canada don't buy as much as a US dollar, especially American products.

Ralph

tallgirl

Re: Utility payouts per KWH

russ wrote: »

@tallgirl - You already are when you take the hit on efficiency.

I'm not convinced the "hit" is anywhere near as bad as many people claim it to be. It's certainly not the cost difference between retail and wholesale power.

In particular, for about 6 months last year, between the time I realized TXU Energy was ripping me off and I switched to Green Mountain, I reduced "sell power" by about 95% through aggressive battery use, while only barely increasing net power purchased from the utility.

You might be thinking about pure off-grid systems, which spill large amounts of power with excessively long absorb and float times. That oft-quoted 50% end-to-end efficiency most certainly doesn't apply to battery-backed grid-interactive systems -- and $0.075 / $0.145 is close enough to 50% that the price difference alone would cover the system inefficiency at more realistic values.

BB.

Re: Utility payouts per KWH

Tall Girl,

I agree that hybrid (grid tie with battery backup) which keep the batteries floating should be much more efficient (maybe around 0.95*0.95=0.90 overall double conversion efficiency or 0.77*0.95=0.73 for Hybrid system when using PV Watts program).

However, have you worked out the cost of batteries + replacements + hardware vs kWhrs generated... The simple formula I have used assuming 20 year period:

• (Installed costs + battery replacements + other service costs) / (20 years kWH production) = $$$/kWHr

Are you expecting a reduction in battery bank life because of cycling (you talk about aggressive battery use) vs float service? In theory--you should be seeing a fairly obvious cost in replacement battery costs because of the cycling.

Just using a simple formula of AC charger + battery bank + Inverter (for peak shaving/load shifting) seemed to cost around $0.45 per kWhr just for hardware + battery costs over 20 years--not even including the cost of power itself.

In Northern California, we have a spread of $0.30 vs $0.09 per kWhr (summer peak vs off peak Time of Use) power costs. Even with that spread of power costs--I could not justify a battery bank / Off Grid system for peak shifting when I looked at it before.

-Bill

tallgirl

Re: Utility payouts per KWH

BB,

It's not the peak versus off-peak difference, it's the buy versus sell spread.

I've not seen a wear-and-tear difference because of what happened last year. I'm sure if I kept it up I'd have seen something. But without the ability to run the system the way I did, I'd have been giving TXU Energy power and not been able to do anything about it. Other than whine.

BB.

Re: Utility payouts per KWH

tallgirl wrote: »

It's not the peak versus off-peak difference, it's the buy versus sell spread.

Tall Girl,

Actually, the Buy vs Sell difference is the same, for my utility as I do for my GT installation... More or less I sell during peak (noon-6pm Mon-Fri) and I buy off peak... For me that difference is $0.30 - $0.09 = $0.21 per kWhr "Spread".

When I just went through and did a simple cost calculation for the hardware and battery costs for time shifting/peak shaving my energy use -- Just cycling X kWhrs per day through a battery bank (charger/inverter, no solar panel costs)--I got a estimated cost of $0.45 per kWhr for the privilege (just cost of hardware + multiple batteries over 20 years divide by 20 year kWhr "shifted").

At least from my way of thinking--you would need a spread in the buy/sell pricing of at least $0.45+cost of power per kWhr to just break even. And since there is a loss between Power Line and Inverter output (charging losses, battery losses, inverter losses)--I even added the 80% eff charger + 80% battery + 85% efficient inverter = 54% end to end losses (have to buy almost 2x the power to offset use--Those numbers are probably on the pessimistic side--but the losses for shifting power are real.

I am not saying it is not worth having a Hybrid system (grid tie + off grid capable inverter system)--I just did not see the cost justifications of cycling the batteries.

In your case, you already have the batteries--so your incremental cost increases would be based on reduction of battery life for Float vs XX cycling lifetime.

If your float life and cycle life is roughly the same--then there is no incremental costs for you.

-Bill

tallgirl

Re: Utility payouts per KWH

Bill,

Not all of my power is time shifted. I have software which manages the charge state that avoids spilling power, so the actual change in state of charge is greatly minimized, while also reducing the amount of power that has to be sold rather than spilled.

I'm very surprised that you came out with a cost for power that was that high. Care to share how you calculated that?

solarix

Re: Utility payouts per KWH

Here in Arizona, my local utility just implemented what is called a "super-peak" rate. For 3 months in the summer, between 3 and 6pm, the rate goes to 49+ cents/kwh! Otherwise, the "normal" peak rate is 22+ cents. The good news is that the off peak rate is less than 5 cents. As long as your A/C use is not extravagent, this really benefits grid-tie. And now a southwest facing roof is better than a south one. Still can't justify a battery backed system for power shifting though.

GreenerPower

Re: Utility payouts per KWH

tallgirl wrote: »

I'm very surprised that you came out with a cost for power that was that high. Care to share how you calculated that?

I'm in agreement with Bill ball-park wise. Here is how I see. With grid-tie battery system, there are 2 scenarios

1) PV energy goes through CC and inverter to offset AC loads directly. In this case only efficiency of CC (90% assumed) and inverter (another 90%) assumed are involved. Total efficiency is 81%
2) PV energy goes through CC to charge battery to time-shift and from battery to inverter to AC loads. In this case, another battery efficiency is involved (80% assumed), resulted in total efficiency of 64%

Say it cost 8$/Watt on average for PVs, inverters, CCs, batteries over 20 years. The cost per KWhr is, assuming 4-hr sun/day on average:

8($/Watt) / (4 hr * 365*20 / 1000 ) / 0.81 = ~34 c/KWhr for case #1
8($/Watt) / (4-hr *365*20 / 1000 ) /0.64 = ~43 c/KWhr for case #2

For case #2, if there is price difference between buy/sell from utility then the cost per KWhr is reduced by the difference. For Julie case, some percentage falls to case #1, the rest on #2 with no difference in utility price difference due to time-shifting. So, her effective cost is somewhere between 34c and 43c /KWhr .

And for reference, for bettery-less grid tie, if the efficency is, say, 90%, the cost is (7.5 $ /Watt assumed since there is no battery)

7.5 ($/Watt) / (4 hr * 365*20 / 1000 ) / 0.9 = ~ 29 c/KWhr in Bill's case, and he gain additional 21c/KWhr due to the utility price spread for time-shifting. At the end, his effective cost is ~ 8c /KWhr

With today's PV price, it's probably less than 8$/Watt but probably won't stay this way for long. We can fudge these numbers some but ballpark wise, the end result won't chage much.

GP

wmwinn

Re: Utility payouts per KWH

In New Mexico, the utility pays for solar generation as an R.E.C at $0.13 per KwH. Add that to the "avoidance" of not purchasing each kWH at $0.11 makes a total of $0.24 per KWH produced.

a0128958

Re: Utility payouts per KWH

tallgirl wrote: »

... I'll be darned if I'm going to pay $0.145 / kwh (what I pay Green Mountain) when I buy back the same KWH's I sold for $0.075 / kwh (what TXU Energy pays).

In TX the 3 primary 'utilities' (actually Retail Electric Providers - REP) that are paying for KWHs are Green Mountain, Kinetic and TXU.

My research match's up to Julie's. While Green Mountain and Kinetic buy back KWhs at their retail pricing, their retail pricing is higher than many 'utilities.'

My plan, living in TX too, once my system comes on line, is to stay with TXU, with a lower kWh rate ithan Kinetic and GM, and who buys kWh at a flat 7.5 cents.

Best regards,

Bill

poleikleng

Re: Utility payouts per KWH

National Grid (Massachusetts)

Net Metering Credit: October/November 2009; 0.03888385

Net Metering Credit: November/December 2009; 0.04420644

tallgirl

Re: Utility payouts per KWH

GreenerPower wrote: »

I'm in agreement with Bill ball-park wise. Here is how I see. With grid-tie battery system, there are 2 scenarios

Well ... a lot of assumptions about battery-less versus battery-full involve believing that battery-less inverters somehow output closer to the panel wattage and battery-fully systems have all these conversion losses. The battery-less systems I've seen, and the one that I'm monitoring so I can add SMA support to my product, all harvest =less= total power from an array than do the battery-full systems I've seen and monitored.

If the weather would improve I'd be able to get better hard numbers, but battery-less looks to be just a few percentage points -- less than 10, and probably closer to 5 -- more efficient. This is exactly what OutBack found years ago when they were testing the first batch of G-series inverters. Intuitively it makes sense -- a battery-less array is yanked around a lot harder by the inverter, resulting in less solar harvest, while the battery-full system is losing power to floating batteries.

GreenerPower

Re: Utility payouts per KWH

tallgirl wrote: »

... but battery-less looks to be just a few percentage points -- less than 10, and probably closer to 5 -- more efficient. This is exactly what OutBack found years ago when they were testing the first batch of G-series inverters. Intuitively it makes sense -- a battery-less array is yanked around a lot harder by the inverter, resulting in less solar harvest, while the battery-full system is losing power to floating batteries.

Well, those like the GTs are operating directly from high string DC voltage, that's why their conversion efficiency is in the ~ 90%. Assuming equal MPPT efficiency, the battery-base system has DC-DC conversion efficiency, (~ 90% of the MX/FM60), the OB inverter has low 90% inverting efficiency and battery is ball-park ~80% energy in/out efficiency, lower or higher depending on type/brand . These efficiency in series that make the battery-based system total efficiency much less compared to the battery-less. All these are realistic numbers.
Each, batteryless or battery-based, system has it's own space and application. That's why both co-exist and people pick one more suitable for their needs.
GP
PS: knowing these but I still have a battery-based system for myself since my priority is backup power during outage.

BB.

Re: Utility payouts per KWH

There is System/Electrical Efficiency:

• Grid Tied: 0.77 solar panel + GT inverter efficiency
• Hybrid GT: 0.77 solar panel + MPPT charge controller * 0.92 Hybrid Invtr = 0.71
• Off-Grid "best": 0.77 solar panel + MPPT charge controller * 0.92 Hybrid Invtr * 0.9 AGM Batt Eff = 0.64
• Off-Grid "typical/conservative estimate": 0.77 solar panel + MPPT charge controller * 0.85 Invtr * 0.8 Flooded Cell Batt Eff = 0.52

Then there is Cost Efficiency... Battery costs, replacement costs, maintenance time (cleaning, watering, etc.), "extra hardware" (wiring, fusing/breakers, charge controller), etc...

Some folks will choose GT + Generator (my personal choice--power outages are rare and short--except if we get hit by a once in 100 year earthquake)... Others will choose Hybrid GT + Batteries (and usually generator backup)...

No right answer--everyone has their own requirements and acceptable levels of risk/reward levels. But stepping back and evaluating the cost/benefit ratio (instead of just Power Option A / Power Option B ratios) is important.

More power to you all!

-Bill

niel

Re: Utility payouts per KWH

bb,
sidenote- "More power to you all! "

that makes a good signature saying and you should go with it.8):D

audredger

Re: Utility payouts per KWH

You may know Solar B.B. but, your geography need some work. San Fran is Central California, Redding and north is Northern California. I live 14miles South of Medford, Or; That's Northern CA.

All that aside: didn't the governator jus sign a bill that said all the power companys in CA had to pay us for our excess power? No more net-zero
Mike

BB.

Re: Utility payouts per KWH

audredger wrote: »

You may know Solar B.B. but, your geography need some work. San Fran is Central California, Redding and north is Northern California. I live 14miles South of Medford, Or; That's Northern CA.

I know I am being ragged on for something--still trying to figure out what. :p:D

Northern California by that all-knowing Wikipedia:

Northern California is the northern portion of the U.S. state of California. The region contains the San Francisco Bay Area, the city of San Francisco, San Jose (the third-largest city in California), Sacramento (the state capital), as well as the redwood forests, the northern California coast, the Big Sur coastline area, the Sierra Nevada including Yosemite Valley and Lake Tahoe, Mount Shasta (the second-highest peak in the Cascade Range), and the Central Valley, one of the world's most productive agricultural regions.

Politically speaking--the great majority would probably be happier with a Costal and Inland California split.

All that aside: didn't the governator jus sign a bill that said all the power companys in CA had to pay us for our excess power? No more net-zero
Mike

Every time they sign a bill--I check my wallet... It is about getting to the point where I may have to "live in Nevada" for 6 months + one day a year to get out from the taxes "they" are burying us under (and they are looking for another $20 Billion to make it through the next few months). :grr

-Bill "get me out of here" B.

audredger

Re: Utility payouts per KWH

It's ok Bill, Most of California doesen't know there is a whole other state above SF. Sacramento sure doesen't. Look up The State ofJefferson. http://jeffersonstate.com/

Wallet? what wallet? They took my livelyhood away with SB670! au (atomic symbol for gold) dredger

audredger

Re: Utility payouts per KWH

I guess this ( I )am getting a little political.... my bad!

BB.

Re: Utility payouts per KWH

As long as you can tie the politics back to energy (somehow :roll:) -- you are golden.

-Bill

tallgirl

Re: Utility payouts per KWH

GreenerPower wrote: »

Well, those like the GTs are operating directly from high string DC voltage, that's why their conversion efficiency is in the ~ 90%. Assuming equal MPPT efficiency, the battery-base system has DC-DC conversion efficiency, (~ 90% of the MX/FM60), the OB inverter has low 90% inverting efficiency and battery is ball-park ~80% energy in/out efficiency, lower or higher depending on type/brand . These efficiency in series that make the battery-based system total efficiency much less compared to the battery-less. All these are realistic numbers.
Each, batteryless or battery-based, system has it's own space and application. That's why both co-exist and people pick one more suitable for their needs.
GP
PS: knowing these but I still have a battery-based system for myself since my priority is backup power during outage.

The point is that battery-less inverters, such as the SMAs, don't have the same MPPT efficiency as something like an FM-80 -- and properly sized an FM-80 is well into the mid 90's on efficiency. My suspicion is that ripple because by direct conversion from PV power to AC power in battery-less inverters is causing a loss in the solar harvest.

Battery =efficiency= isn't an issue since the only losses for batteries are float power, which is dependent both on capacity and technology. Size the batteries towards the low end of requirement, use AGMs, and float losses go way down.

As BB pointed out, 0.77 is typical for straight grid-tie, and what I've seen for "Hybrid" OutBack systems is closer to 0.74 than the 0.71 that BB mentioned. 0.74 / 0.77 is 96%. 0.71 / 0.77 is 92%. That's not a bad percentage rate, either way, for the capabilities that battery-backed gives.

Taking the difference in cost, which for "installed costs" is about $1 per watt DC with most of my clients, the "cost efficiency" is (0.92 / (8 / 7) or 80%. If "buy" cost is 125% or more of "sell", battery-backed is the correct solution since it's the only solution that allows power shifting. The greater the spread between "buy" and "sell" prices the more inefficiency is acceptable on purely economic grounds.