Not Really Net Metering

SolarLurker · August 2010

I recieved my first electric bill after firing up my system. I have learned that is I use any electricity from the the grid I am billed taxes on what was used even if I produce more than used. As such I would like to shift as much of my loads as possible to when I am producing electricity.

Is there some sort of capacitor or battery bank that I could use to store extra production during the day, and consume it at night?

BB. · August 2010

Re: Not Really Net Metering

Different Utilities and states have differing net metering programs...

Mine, simply "unwinds" the meter when I am generating, and the meter moves forwards when using more power... I pay ~$5.50 a month minimum charge and at the end of one year, I either pay what I owe, or my account is "zeroed out" (they are changing the program, I may get a little bit of cash back now if I generate extra power over the one year period).

Some others, you may have two meters... One to register the power you generate and a second one to report the power you use.

They may--work it out through billing (like my one meter)--Or they may pay you for the energy you generate and bill you for the energy you use.

In many places--they pay you at retail or more for your power (the subsidy) and you have the privileged of buying it back at lower cost (retail). Even with taxes--you should come out ahead...

It would be interesting to hear exactly what your program is... If you have two meters--then I am not sure that we suggest a system that would be "legal"...

If you have one meter and it registers a different amount for what you purchase vs excess generated--then, I think, the Schneider/Xantrex XW Hybrid Inverter system can be programed to do what you are asking.

However--that would mean new hardware, new wiring, possibly new charge controllers (not sure--they have just released new software to manage GT+XW setups--we would need to research this), and--Of Course--A good sized battery bank.

The big issue is the added cost for the hardware and battery replacement/wear-out from shifting your power to a different time of day...

Every time I have worked out the math (assuming 20 year hardware life, and replacing the battery bank every 6-10 years--or getting a more expensive 20 year battery bank)--Just the 20 year costs add up to ~$0.45 per kWH for the privilege of load shifting...

If you add another 20-30% for losses (charging the battery bank during the day, discharging the battery bank and inverting the power for use at night)--Your power losses may be more "expensive" than the taxes you are currently paying.

Lastly--Have you gone over your bill with the utility/state PUC (Public Utility Commission)... In California, about 5 years ago, PG&E (northern California's power utility) change the way they did "tiered pricing" and really hit people with A/C and Electric Vehicles very hard (generate solar during the day--get Time of Use payments around $0.30 per kWH, buy power back at night at $0.09 per kWH)... The way the utility changed their interpretations of the rules--Many people dropped out of the EV Time of Use program at the time... As I remember, basically the utility increased tiered price levels on both power generated and used--So if you used 1,000 kWH at night, and generated 1,000 kWH during the day, instead of placing the customer at the 0.0 kWH pricing level--The utility priced it as if you "used" 2,000 kWH worth of power (tiered pricing can be as low as $0.09 or as high as $0.60 per kWH--so this was a big deal).

The billing was appealed to the state PUC and they ruled in favor of the consumers that "Net Metering" was simply "unwinding" both power used and tiered pricing. Perhaps, you can argue that the program says "Net Metering" and that means the taxes are supposed to "unwind" too (generate 1,000 kW, use 1,000 kW==Net is 0.0 kWH , not the taxes on 1,000 kWH "used").

Sorry for the long post--but Net Metering details (add tiered pricing and Time of Use pricing, and year end payouts) can make the programs almost impossible to understand and predict your power bills.

-Bill

SolarLurker · August 2010

Re: Not Really Net Metering

It seems to me if you zero out the bill there should be no taxes, I would'nt mind a mimimum bill even. Something about the taxes just bugs me.

I have tried to get clarification on how the company handles net metering, and even one I speak to just gives me a different answer.

We, dont have tou or a feed in tarrif. The meter is digital and has two readings on shows what I feed back and the other showing what they sold me.

GreenerPower · August 2010

Re: Not Really Net Metering

Regardless of the type of meter installed, you can always "net" your production against your usage if your production is less than your usage (instantaneously). If your production is more than your usage then depending on the type of meter and net-meter and billing policy specific to state and the electric provider, how the "sell" amount is paid i.e. you can or can not "store" the extra in the grid and use it later in the day.

In my TX state, most providers won't pay for amount you "sell" back. A few would pay at "bulk" market rate (i.e. very low compared to retail buy rate). So even in the same state, it changes depending on provider's policy. Also most states would calculate the net monthly (can not apply extra production to other months' usage in the year). CA and some other states would net annually i.e. the "sell" is net against your usage anually.

If your system is battery-less grid-tie, you don't have much option. If your system is battery based, most would have a mode called HBX (High Battery Transfer) or similar.
With this, you can set it up to use from battery until its voltage is down to some programmable preset value then it would switch to use the grid. The drawback is that you need a separate load sub-panel and when the inverter switches to use grid, it would try to use grid to re-charge the battery. You can lower the charging current or disable the charger to use PV to charge next day.
This works, if on monthly average, your production is less than your usage. But you would need to be careful not to let battery discharged so much i.e. need to charge from grid once in a while (since PV production could not offset all usage). Whether the extra cost for battery-based system worth this (vs. selling back at low or no cost).
If your monthly production generally exceeds your usage, this won't help since once battery is full, extra PV energy is wasted (might as well dumping back to the grid to cut down CO2).

Hope this helps,
GP

nvyseal · August 2010

Re: Not Really Net Metering

In the beginning I was just about as confused as you, but after looking at what others are paying as a minimum I am happy to pay the little fees and taxes they want to charge instead of having to pay high line/transmission charges that the utilities could impose upon you. (my post here) Please read BB's #4 post in that thread.

If I were you, be happy, and dont rock the boat, because they make the rules. even batteries/maintenance are going to cost you more than the taxes you are paying now

Solar Guppy · August 2010

Re: Not Really Net Metering

Its very common to not get full credit on the taxes, and its not the utility's fault but the local or state government.

There is no concept of negative taxes, which is what one needs to get a 1 to 1 credit when you have dual electronic registers, not an old style mechanical meter. I have a similar issues here in Florida, I do not get credited the local county utility tax on any excess generation. The core issue is the power company is required by law to collect tax on what it sells, there is no companion law that says an end user can get tax credits for selling energy.

In my case, its about a ~10% hit on only the energy that is in excess of usage, keep in mind a large portion of the energy is used in the home long before there is enough to show power exported, so its a very minor hit to the value of your energy.

In my case, water and electric is on the same bill and when I generate a net positive for the month, my excess electric pays off the water bill

... so quirks work both ways.

Cost wise, is not worth worrying about as your looking at a 1 dollar a watt solution ( battery's and inverter to support selling from battery's ) to load shift for something that works out to less than 1 cent watt is cost hit to your the exported solar

Not Really Net Metering

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