I have been thinking about installing a photo voltaic system.  I have lots of land and lots of unobstructed southern exposure.  Would there be any equipment advantage to not connecting the solar power to the house at all, and just have it running the utilities meter backwards?

I know I need more info on NYSEG's (my utility) power generating policies.  Talked to them once, but only got to the application part.  I will need to call them again.

Anyone have a source of good used solar panels?

-Rosalinda

Rosalinda-

You ask about going into competition with a utility by setting up your own PV system but tying into their grid and not your house. I assume that that would not be allowed to do this on a household basis by the utility. In Colorado, the agreement is that you are supposed to be limited in the size of the PV system that can be installed to 120% of your electrical needs.

It would not make economic sense here to add electrical energy to the grid and not the house. We pay $0.10 per kWh for electricity supplied to the house, and are compensated $0.03 per kWh for energy supplied to the grid.

What is your motivation for your question? On the surface, it seems to make no sense, and it almost certanly would not be allowed, but as your say, you need to check with the local utility.

You also ask about buying used solar panels. Keep in mind that some folks are selling new panels at about $1 per Watt currently as some manufacturers are going out of business. However, panels alone do not make a system, as inverters, wiring, and mounts also represent a significant investment.

This isn't exactly "going into competition with a utility" unless the grid operator is a vertically integrated entity that owns and directly controls all of the generating capacity on their grid, which is rarely the case. What she is taking about is becoming an independent generator selling to the utilities. This is becoming quite common in areas where there are financial incentives for buying renewable power built by the legal regulation structure. The contract terms will of course vary, and there are regulatory hurdles to clear, but if you have acres (or tens/hundreds of acres) on which to develop the PV powerplant you can probably find investors willing to set up the project and finance it for you.

Typically arrays of 10kw or less and attached to a home or business fall under different regulations, and are often net-metered (as per Lee describes.)

BTW: Lee, are you net metered at retail, getting paid wholesale for any excess production over a weekly/monthly/annual period, or is it integrated continuously, where if you draw a kilowatt over the PV output for an hour they nick you a dime, and if you deliver a kilowatt extra for the subsequent hour they pay you 3 cents? (IIRC Most sub-10kw situations in New England are net-metered at retail on an annualized basis, but any annual excess isn't compensated. But I have chased the details recently, and regulations are in a state of flux.)

The rules here are set by the state (Colorado) and the utility (Xcel) that is headquartered in Minnesota(?) but serves a number of states. Houses here are net-metered, and the "account rebalancing" is performed on an annual basis. I have never had a month where I did not generate more than I use, so my electric bill is always just the connection fee of about $7.42 per month. Then after a year, they send me a check for the excess, but payment is the wholesale price of about $0.03/kWh. I think that for any month that I used more than I made, I would pay $0.103/kWh on that monthly bill. This arrangement seems to be typical of some western states. In California there is time-of-day metering, so things are more complicated. In my case there was also a rebate from the utility at initiation of the system, maybe about $2.50/W, but that has been variable since that time. Installed costs for 2012 are projected to be $4.75/W for an installed, turn-key system in my local small town area, before any federal, state, or utility rebates. The state does not pay rebates if the utility does.

I am publishing monthly performance data on 3 PV systems in my local area at: http://www.residentialenergylaboratory.com/comparison_of_pv_systems.html.
The cost for these systems, after rebates, ranged from $1.73 to $2.50 per Watt, all professionally installed. For a (guaranteed) lifetime of 25 years, I estimated that two of these systems will produce power at $0.064/kW and $0.080/kW compared to the current utility cost of $0.103/kW, while the third system on a different utility will produce power at $0.082/kW compared to the current utility cost of $0.130. All of the assumptions used in the cost analysis are provided at the web address cited above. This geographic area is better suited to solar energy than most places in the U.S. with the exception of the southwest, so results will vary with location. Interestingly, performance results (kWh/kW rating) do not seem to vary for the 3 different manufacturers represented in this study.

If houses are sold before the 25 year lifetimes assumed, then the economics will be influenced by the effect of the PV systems on the sale prices. Again, this subject is addressed with references to actual data at the above website.

Back in the Jimmy Carter era, which is the last time syndicators sold tax shelters based on energy credits, things did not end well. Many of the syndicators failed after Reagan pulled the plug on the tax credits, and with no one to receive or write checks, the investments went bust too. "Joint and several liability" are four words that would send me scurrying for the door. It means that the lenders can collect any amount of the debt from any borrower who can pay. Limited partnerships may also have a provision that allows the general partner to call for more capital. I am not saying don't. Just be careful.

toddm-

I am not sure who your comments are directed towards, or what they pertain to. If they were directed at my post, I don't understand your point. In the case of my own PV system, any change in rebate structure has no impact, since the rebates have all been settled at the time of initial purchase. So even if Reagan comes back from the grave to upset the rebate structure, it will no impact on the economic analysis that I referred to.

I hope that if the rebate structure for solar is reduced, that we will also see a repeal of the Price-Anderson Nuclear Industries Indemnity Act that limits the nuclear industry for nuclear accidents, and that we repeal the oil industry subsidies inclucing the domestic manufacturing deduction, the deduction for treating royalties paid to foreign governments as deductible taxes (sort of the opposite of the first deduction), and deduction for intangible drilling costs.

OK, I guess I was not clear as to what I was thinking of. I do not want to become a major generator of electric, just put in enough panels to cover some or all of my usage, 5 to 6000 kWh a year. But instead of attaching the panels to the electric system in the house, I would just hook it up to the utility to run the meter backwards to cover some or all of what I use. I would put the system right near the meter pole so there would not be problems with energy drops. I was wondering if there would be a simpler wiring and inverter system needed to hook to the utility, rather than having the system hooked to the house in addition to having the utility grid hooked to the house.

-Rosalinda

Utilities are already nervous about having people connecting into their grids. They have finally worked out an agreement to use a single net meter and other protocols to measure both energy coming into the house and energy being pumped into the grid. By most pricing schedules, it would be advantageous to use net metering as they have agreed to rather than what you are proposing. You appear to want to use two separate meters to accomplish what they normally do with one meter. As you have said, you need to ask the utility, but I cannot imagine an advantage for them or you to try to develop some new protocol to do things differently using more hardware than they normally would.

Thanks Lee, that is good info to know. I will have to talk to the utility and get more details on just how they set things up, but I imagine it is as you have described.
-Rosalinda

Dana wrote that investors would find Rosalinda if she wanted to get into the generation biz. My post was to suggest that it wouldn't necessarily be a good thing.

That said, there is no guarantee that Xcel will continue net metering forever, or paying for excess production, and your 25-year guarantee is only as solid as the guarantor.

No need to resurrect Reagan for the Empire to strike back. Utility lobbyists are hard at work right now.

Posted By Rosalinda on 15 Jan 2012 08:23 PM
OK, I guess I was not clear as to what I was thinking of. I do not want to become a major generator of electric, just put in enough panels to cover some or all of my usage, 5 to 6000 kWh a year. But instead of attaching the panels to the electric system in the house, I would just hook it up to the utility to run the meter backwards to cover some or all of what I use. I would put the system right near the meter pole so there would not be problems with energy drops. I was wondering if there would be a simpler wiring and inverter system needed to hook to the utility, rather than having the system hooked to the house in addition to having the utility grid hooked to the house.

-Rosalinda

Once you're wiring at the AC output of the inverter the power losses from wiring remotely are negligible even over some real distances.   At the low voltage DC/panel side of the inverter it takes much fatter wire.  If you wanted to site the PV array and inverter 500' away from the inverter it's an issue, but if the inverter & array are remote from the point of metering, not so much.

To generate 6000kwh/year the array  would fall under the typical 10kW peak most utilities have for net metering at retail (as in Lee's case), where your meter just subtracts from the net billing when the PV output exceeds the load at the house, forward when the immediate load exceeds the immediate PV output.  This is a better deal financially than net metering at fixed-rate wholesale, where they charge you residential retail when your PV exceeds your load, but the wholesale average when you have excess.

Investor operated array deals seek a demand rate or time of day net metering which is more complicated, but since peak-demand typically occurs during periods when PV output is high, and off-peakhours typically occur at night, it's an even sweeter deal. But the complexity of the meterng and accounting makes it uneconomic for small arrays.  But if you have idle acreage and room for 100kw+ of panel you could probably make some money off it.

In many areas where utilities are required to increase renewables even tiny PV arrays (like Lee's) can often make money selling the solar-credits of your PV output to utilities (often bundled by regional aggregators- eg . NEPOOL ) a market created to incentivize homeowners to make the investment while simplifying the accounting for both the homeowner and the utility, and saving the utility the capital & management costs. At current market rates for solar credits it dramatically improves the investment economics, and can make it significantly net cash-positive even if net kwh output undershoots annual power use by quite a bit.

Posted By Dana1 on 16 Jan 2012 11:19 AM

... At the low voltage DC/panel side of the inverter it takes much fatter wire.  If you wanted to site the PV array and inverter 500' away from the inverter it's an issue, but if the inverter & array are remote from the point of metering, not so much.

... This is a better deal financially than net metering at fixed-rate wholesale, where they charge you residential retail when your PV exceeds your load, but the wholesale average when you have excess.

...

Dana, I think in this case, since it's a grid-tie-only (i.e. batterylesss) system, on the DC side of the inverter the voltage will be 300 - 500, thus allowing for smaller wire diameter sizing (larger gauge #) and thus lower cost of panels to inverter connection.  Thus I'm not sure it's a significant issue, allowing for the panels to be a good 500' or more away from the inverter, and relative to the other costs for a 6 MW system.

The connection from the inverter to the grid will probably be at 240 VAC, thus too allowing for reasonable size wiring, assuming the inverter is close to the grid connection.

I think above you meant to say "when your load exceeds your PV."

Best regards,

Bill

I stand corrected (on both the likely DC voltage and phrasing)- thanks Bill! (There's rarely an editor reading over our shoulders on web-forums, eh? ;-) )

Either way, it probably only takes a ~5kw or smaller array to cover the 6000kwh/year, and 5kW @ 240VAC is only 21 amps, which doesn't take some monster-fat cabling to run a few hundred feet, if need be. I suspect the regs for running 500V DC over distances may be more stringent, even if it's skinnier wire. (I haven't visited that part of the electrical code recently.)

I was thinking about this last night, and thought more info might help. I have a farm, and the one meter for the entire farm (4 buildings) is on a pole where the service comes in, not on any of the buildings, . The main box is just below the meter, and the electric is distributed to the various buildings from this box. The array would be hooked up to the meter on this pole, and I think locating the array near the pole would work out fine.

Wouldn't this simplify the wiring and controls in several ways?

I am in the Finger Lakes of NY State, not exactly the best place to generate electricity, but still doable. My nephew is building a power company in the Negev in Israel, has a 5 MW system built and operating, and is hoping to become a major energy producer for Israel. Now THERE is a place with lots of sun!

Thanks all for your input
-Rosalinda

Posted By Rosalinda on 15 Jan 2012 08:23 PM
OK, I guess I was not clear as to what I was thinking of. I do not want to become a major generator of electric, just put in enough panels to cover some or all of my usage, 5 to 6000 kWh a year. But instead of attaching the panels to the electric system in the house, I would just hook it up to the utility to run the meter backwards to cover some or all of what I use. I would put the system right near the meter pole so there would not be problems with energy drops. I was wondering if there would be a simpler wiring and inverter system needed to hook to the utility, rather than having the system hooked to the house in addition to having the utility grid hooked to the house.

-Rosalinda

I think the summary here is:
* you have about a 6000 kWh / year usage that you'd like to investigate if it's cost economical to put up a solar PV system to offset this usage - i.e. no electric bill.
* you live with enough acreage such that it's probable that you have the ability to install solar PV panels in the most economical manner.

System design comments:
(1) To generate about 6000 kWh / year probably does not require a very big solar PV system for your location - I think a solar PV system less than 10 KW (DC) is a reasonable assumption without needing to look at PVWatts for your location.
(2) A least expensive implementation of a 10 KW or less system in your case is indeed to put it out where your meter is and do it via a pole mounted solar array system (i.e. no panels on a structure needed).

Whether or not it's cost economical depends primarily on three key factors:
(1) Availability of an unobstructed south facing, unshaded location (sounds like this is indeed very doable for you).
(2) What kind of incentives (i.e. utility rebates, local govt gifts, etc.) are available to you.
(3) What kind of net metering arrangement is available to you from your utility.

There are many items that affect the cost economics of a solar PV system, but they're minor compared to the three above that are absolutely fundamental.  In fact, these three are 'make or break' items.

I think the above is a good summary, and that the rest of the subject is the details behind the cost of a pole mounted array, incentive details available to someone at your location with your utility, and how much the utility wants you to be using solar (as evidenced by its net metering policies).

Hope this helps.

Best regards,

Bill

Posted By Rosalinda on 16 Jan 2012 10:22 PM
... My nephew is building a power company in the Negev in Israel, has a 5 MW system built and operating, and is hoping to become a major energy producer for Israel.  ...

My guess is, for your location, your nephew could easily specify the most cost effective details for your 0.010 MW (DC) solar PV system (i.e. a 10 KW or less system - tiny compared to his 5000 KW system).  Sounds like you have a very talented nephew!

My further guess is, for your location, it's a straightforward X number of poles with 30 - 40 panels total, with a single inverter very close to where your single meter is.

Key items that you need to investigate, to determine if the economics make sense relative to your electric bill, are the two I mentioned in the above earlier posting: available subsidies, and available netmetering agreement(s).

Good luck!

Best regards,

Bill

Just in case anyone is interested -
http://www.jpost.com/Sci-Tech/Article.aspx?id=251304