Preprepared Roofs and Backfeeding Questions

Re: Preprepared Roofs and Backfeeding Questions

And to be clear--GT inverters in current production are designed and tested to meet specifications such that if the voltage or frequency (or power line quality) is out of specification--the inverters are designed to shut down in a few cycles (5060 cycles per second). Plus, as the inverters operate as a "slave" to the grid--they are not even capable of operating without a "master" (such as the utility power) waveform to follow (as always--exceptions to the rule, there are types of inverters that can do both GT and Off Grid power--so they have several modes they can operate in).

There is another from of "back feeding" that the specifications talk about... This is the AC mains "back feeding" the DC solar panels... Most (all) GT inverters are designed that they cannot back-feed the panels at all (or meet the requirements in some other way).

The utility and code requirements are to help ensure that the correct equipment is installed and safely wired.

-Bill

Re: Preprepared Roofs and Backfeeding Questions

My system generates around 4,850 kWhrs per year (400 kWhr per month average solar generation)--and we (2 adults/2 kids) use around 250 kWhrs per month (12 month average)... I have Time of Use metering--so, I currently come out with around $300 or so of "excess energy generation" -- which with net metering, becomes worth zero at the end of the 1 year term.

I purchased the system because I saw what California had been doing with the costs of power (and the blackouts around 2000) because of the "deregulation" of power (not deregulation at all--just very poorly thought out and implemented change of regulations that nearly bankrupted our utilities).

We worked at conservation--the usual stuff--insulated a 70 year old home, double pane vinyl windows, new doors, weather stripping, new furnace, energy star appliances, CFL lights (wife still hates the color--but likes the low bills, no A/C, etc.).

Installed more panels than we needed with the plan of installing A/C eventually. But it turned out that insulation/low-E glass and reducing the use of power in the home would keep our internal temperatures pretty reasonable in all but the very hottest weather.

And--still run around after the kids to turn off lights and computers/printers/copiers/home stereo/TV when not in use (use laptops mostly--much less power draw than desktops).

And lastly--kind of thought that electric (or hybrid electric) cars where going to be here sooner rather than later (again--because of the state laws). Been using electric heaters in a couple rooms (rather than central heat) somewhat during the winter because, currently, we have so much "extra" power.

We probably used to use $30-$60 per month of electricity (maybe 300-600 kWhrs per month--before kids)--that was years ago with older fridge and when "I did not care as much" a decade or two ago. We currently use around 180-300 kWhrs per month and have a $5.42 per month electric bill (basically minimum charge with our utility).

Because of the policies from the Carter years--we still have tiered residential rates where the more you use, the higher rates you pay... Almost the equivalent of going to the local quickie mart and buying a gallon of milk for $1.00 and going to Costco (mega-mart) and paying $7.00 per gallon for 10 gallons of milk.

My minimum charges are around $0.09 per kWhr (off peak), and my maximum rate is near $0.60 per kWhr (summer peak)--although, I don't "pay" any more than $0.30 per kWhr because my bill is less than 300 kWhrs per month. The $0.60 per kWhr is for usage over ~1,000 kWhrs per month. The new "Smart Meter" summer peak rates are $0.75 per kWhr for commercial accounts.

One of the reasons I am so concerned about the current Net Metering plan (I buy power at $0.09 per kWhr at night, and get paid $0.30 per kWhr for summer afternoons)--is that, roughly, 1/2 the bill is related to energy charges (cost of generating the power). And the other 1/2 is distribution (and a smaller portion is long distance transmission charges).

If I consume 250 kWhrs per month, and generate 400 kWhrs per month--that is ~650 kWhrs per month I am "moving" across the utility's power lines (basically I shift all of my loads to off-peak use, and nearly full generation goes to the utility during the peak time)... At current rates (around $0.20 per kWhr for flat rate residential at that tier), that would be ~$65 worth of local distribution costs--and I am paying $5.42 instead...

Basically, I am getting a subsidy of $60 per month from the other rate payers (plus the 1/3 rebates/credits I got from the "state and feds" to pay for my install).

And, if I was just paying the $0.12 per kWhr instead (residential flat rate) at 250 kWhrs per month--my bill would be $30 per month...

So--if "everyone" did solar--where would the peak power go during the daytime (my system, ~2kWatts generated for almost 7 hours per day, and I consume an average of 0.49kWatts off-peak. (note that my average generation power is higher than my average consumption power--the power lines need to be sized for the larger generation currents that solar PV generates during the day--and there has to be a "matched" load somewhere to use that power--there is hardly any power storage/shifting in the network today).

Granted--I am "forgiving" $300+ per year in unused power credits--but if I consume more power to burn up the credits (electric power, more electric heat/cooking/etc.)--the subsidies only get worse.

If every home in the state where to do what I am doing right now (solar grid tied; not that could even be practical)--somebody (commercial, industrial, residential minimum charges) would have to pay more to keep the utilities network running as Net Metering is not economically feasible on a large scale--it would drive the utilities back into bankruptcy...

Here is an old thread that I started that showed a school district actually ended up spending more for their power after installing solar because commercial billing is different... There is the energy generation charges, but there is also the other 1/2 of the typical bill which is the "reservation charges"--based on the peak 15 minute period in the last year... And with solar does not reduce that peak (if occurs during dark/cloudy weather)--or could make it worse because it is the peak of solar generation (solar generates 7 hours per day, but there are 24 hour per day loads--so to net to "zero" energy usage--solar peak power has to be higher/longer than average peak power from the loads spread out over 24 hours).

In the end, I installed solar GT because--1. I did not trust the state public utility commission to not further mess-up our power charges (newest "smart meter" plans have $0.60 per kWhr for summer afternoon peak charge for roughly 15-20 days per year when A/C loads near generation/transmission capacity); 2. because I believed that older systems would be grand-fathered in with better rates/terms than newer systems (and so far--that has been true); and 3. that electric vehicles where going to be cost effective because of high fuel/road taxes and the absence of road taxes on electric vehicles (true so far).

In the end, I did it because government "free money" and policies/incentives made the solar PV GT system worthwhile to me as an "investment" to hedge against future energy price increases. However, I am under no illusion that this "fixes" any of our long term financial or energy issues.

-Bill

By the way, what do you mean by "statically unlikely customer"?

Size of system, amount of power I use, reasons for installing solar (not to reduce green house emissions), or what?

Re: Preprepared Roofs and Backfeeding Questions

If I was gong to "prep" a home for solar power on the roof... I would adjust planning codes and create solar access rights such that:

1. A large percentage of the roof face south (or flat roof with access to shade free sun)
2. Roof Angle set to optimum pitch for solar collection (if pitched roof)
3. No obstructions (vent pipes, chimneys, etc.) to east, south, west
4. No power lines/street lights/etc. to east, south, west
5. No tall landscaping to east, south, west
6. South Roofs should have access to sun from at least 9am-3pm to ESW.

Huge numbers of homes do not have access rights to sun (trees, neighboring buildings, etc.). City Planning want complex roof lines to reduce "visual bulk" of homes/buildings (especially in scenic areas), etc...

Other than running an empty conduit from an appropriately sized main service to the roof--most of the costs of an install are parts--not labor, so reducing installation labor costs are not huge part of the bill (certainly solar panels have come way down in price in the last few years, so labor cost is becoming more of an issue).

But the lack of sun and south facing roof face with access to shadow free sun is something that no amount of money can resolve--and stopping even those that can afford the installation to give up).

However, this does not come without costs... Here in California, we do have solar access rights (to a degree) and I could force my neighbors to pay thousands of dollars to trim/cut down their mature/large trees to save me 10% of $30 per month in power costs (there is a nice Redwood that I am watching at in one yard, and a live oak in another)...

Regarding distribution--most of the utility's costs and losses (network vs transmission) are in local distribution... The physical plant costs to supply an average of 0.5 kWatts to a residence that practices conservation are about the same as to supply a drop to somebody who averages 2kWatts of power consumption... (everyone gets a 100-200 amp service and has the same access to peak power--i.e., I can use my power microwave, electric oven, power tools, and electric heaters, etc. just like the person next door). But the residence who conserves, does not pay for the network capacity to supply those peak loads (unlike commercial which pays reservation charges).

And that leads back to the intent to make it economically feasible for a large percentage of homes to install solar PV...

Years ago, there was a large subdivision that was being planned that would have installed solar PV on every home... The utility flat out refused to service the new development if it went forward as planned (I cannot find the article, and I do not know what the eventual outcome was).

Just from the utility ledger point of view... If the average new home (affluent with lots of electrical goodies like A/C, dual electric ovens, lots of accent lighting, etc.) and consumes the national average of 10,000 kWhrs per year--In California, that is near a $200 per month electrical bill per home... If that subdivision was designed to have Solar PV GT systems to exactly equal the homes net electrical consumption--then every home would have a $5.42 per month electric bill... But with infrastructure costs that would be would have supported a $200 per month bill, of which near 50% was allocated to infrastructure payments...

Where would the ~$100 per month money/revenue stream come from to pay for the infrastructure? If it comes from the residences of the subdivision, they would still have to pay at least $100 per month for reservation charges--which make solar even more expensive (at best, you could only cut your power bill by 1/2). Very roughly, the homes are paying only 1/20th of their share of costs for the local grid.

Or would you increase the charges to people who don't have solar? -- Well, that hits the "poor" that don't have solar and those people that can't install solar because of other issues (shading, no south roof, etc.). That is not fair. Charge the Commercial/Industrial customers and have them subsidize the Solar powered homes? That increases the cost of business in California and forces wages down and jobs out of state/country (which is already happening) and increases the price of products and services of the firms that are left behind... Which is just cost shifting.

Regarding Smart Metering and moving everyone to Time Of Use billing--Other than possibly reducing costs (no more meter readers)--Smart Meters are the result of government policies/subsidies that have Meter Companies (and related services) chasing after billions of dollars of government cash...

Another thread I created is Grid of the Future: Smart Meters where we discussed some of these issues (and possible hacking opportunities / network insecurity provided by a "smart grid").

If the utility was so concerned about cutting costs of meter reading--they could have saved 1/2 to 2/3rd's the costs of meter reading by simply going to a 2 or 3 month meter reading schedule vs the current 1 month schedule. And, if they wanted, use predictive technologies to estimate the unread months billing... A lot cheaper (and no hacking opportunities/security holes) than a smart meter.

As to whether or not I am a statical outlier--There are probably two groups of Solar GT owners... Those that are wealthy and have the money to install a system (energy costs are probably not a concern anyway) and those that care about the environment/conservation/etc. and watch their energy use fairly closely (and have already implemented personal conservation measures before even installing their PV array).

While I am not a supporter of "Global Warming"--I am a conservationist/"fiscalist" engineer--I try to leave things a little better than I found them...

However, I find much of government actions to be beset by the "law of unintended consequences" which frequently create the exact effect that they were intended to prevent int he first place (i.e., green polices to create green jobs which create few green jobs and end up killing lots of other jobs in the process while causing un-green damage--such as wind turbines killing birds, dams and turbines killing native fish, salt water intrusion, change in silting patterns, loss of sand to beaches causing shoreline erosion, etc.).

And while one arm of government is subsidizing solar installations (via tax money and by hidden required charges by utilities)--another part is enforcing planning codes (roof lines, community look and feel, landscaping, aerial utility right-of-ways, neighbor additions, HOA covenants, etc.) that make installing solar PV and Thermal almost impossible.

Nothing is "free":

FirstEnergy to give away 3.75 million low-energy light bulbs:

FirstEnergy Corp. is getting ready to leave two high-efficiency light bulbs on your doorstep. But they're not a gift.

The utility will charge average users 60 cents a month extra on their electric bills for the next three years -- $21.60 all together. That covers the cost of the bulbs ($3.50 each), their delivery and the delivery of the power consumers would have used if they didn't have them.

The good news: These compact fluorescent bulbs will reduce your electricity use. If you replace two 100-watt incandescent bulbs with these 23-watt, warm-white CFLs, you'll save $60 by the time they burn out in five to seven years, according to FirstEnergy.
And you'll pay for the bulbs whether you use them or not, so it makes sense to use them.

FirstEnergy is distributing the 3.75 million bulbs to comply in part with an energy law enacted in Ohio last year. The law requires utilities to cut their customers' energy use by 22 percent by 2025. The law also mandates that utilities use solar, wind turbines and other renewable energy sources. The Public Utilities Commission of Ohio approved the light bulb distribution and the extra charge on your bill.

Two CFL's for $21.60??? I can buy CFL bulbs for $1 each all day long... So, instead of 20 CFL bulbs for the whole home--the people only get two for the same amount of money. Sounds really nice.

And, at least from the article (may have been poorly written); "...covers the cost of...delivery of the power consumers would have used if they didn't have them..." It looks like the utility is getting paid by the customers (tax/fee required by law) for not delivering the power the CFL program is saving... :roll:

I am sure the people in Ohio are happy the government is watching out for them.

Not claiming that I have all of the answers--but from an engineering and financial point of view--the picture is pretty muddy for solar RE at the residential level. Instead, it would probably be better to set aside a clear field someplace (in town, or down in So Cal deserts) of xxx square feet per home/business/etc. and install the Solar RE system there (with professional maintenance) vs installing on home roofs just from a cost/efficiency/practicality point of view.

-Bill