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By Russ Finley on Feb 4, 2014 with 11 responses

Maintaining the Grid as Residential Solar Power Increases

SolarFail

Photos courtesy of Activ Solar, Brookhaven National Laboratory, and Avinash Kaushik, via Flickr Creative Commons

It makes little sense to be anti-solar energy in this day and age, although it does make sense to do it right. Even solar can be done wrong. Usurping farmland, forest, or pristine desert tortoise habitats for solar should be against the rules.

I was motivated to do this post by a rare, cloudless, 50 degree day in the dead of winter.

If you put grid-tied solar panels on your house to eliminate your electric bill, you may one day be billed for use of the grid anyway. Some solar panel owners are already paying about 25% for use of the grid. That’s because, like natural gas and coal, solar panels are essentially a source of energy (fuel) for an electrical grid, which is only one component of the total cost. Power grids are like roads and sewer lines in that we all have to pay our fair share for their use. I’m OK paying an extra fee for my electric car which pays no gasoline taxes. I’m also OK with temporary government subsidies to test the waters for new technologies.

Some percentage of most electric bills goes to pay the fuel costs at the power plant. In my neck of the woods almost 98% of our power comes from hydro (90%), wind (4%), and nuclear (4%), which have no or very low fuel costs. Yet we still pay roughly 9 cents per kWh for residential electricity. The average American pays about 12 cents. The difference in cost (12 – 9 = 3 cents per kWh) is mostly fuel. The other 9 cents is what it costs to get the electricity to you, expand or maintain the grid infrastructure, pay for Federal programs, etc. This means that someone who offsets all of their electricity use with grid tied solar panels might one day, in theory, end up paying something like 75% of their original electricity bill (12 cents – 3 cents for fuel costs = 9 cents = 75% of 12 cents).

However, if your highest priority is to use less fossil fuels (willing to spend more to accomplish that), then volunteering to pay more for your electricity isn’t necessarily a bad thing, in fact, one could argue that it’s a noble thing. If wind, solar, and nuclear really do cost more than fossil fuels, maybe paying a little extra to get rid of fossil fuels isn’t a bad idea.

One method to reduce the various monthly grid use charges beginning to show up on electric bills by owners of grid-tied solar panels (who are essentially very small power companies) is to find ways to use more of the electricity in your own home (send less of it to the grid where you will likely be charged per kWh for your share of upkeep).

This is a lot easier said than done, and how cost effectively it could be done depends on where you live. A typical portable space heater (or single-room window-mounted air conditioner) that you plug into your wall uses about 1000 watts. If you put a 12 kW solar panel system on your roof it will be able to power 12 space heaters (or air conditioners) when the sun is optimal. You can see how hard it would be to consume the equivalent of 12 space heaters or air conditioners whenever the sun is shining.

The most straightforward way to reduce fossil fuel use and send less electricity to the grid in cold places in the winter is to heat your home with electricity (resistance heaters or heat pumps) when the sun shines, and if your nighttime electricity is being generated by coal or natural gas, switch to using natural gas for heating at night. Gas is more efficient than electricity for heating because it is piped to your house and used directly instead of being piped to a power plant, converted to electricity, and then sent to your house by wire with all of the attendant losses involved.

The above idea may or may not save you money depending on the price of natural gas, electricity, and cost of installing two heating systems.

If your electricity is coming from hydro and/or nuclear then you will use less fossil fuels by heating with electricity day and night. Considering that it wouldn’t reduce CO2 emissions, you might be asking why anyone who is getting their power from hydro wind or nuclear would put solar panels on their house?

Well, if you live in a very sunny place that also has high electricity rates, especially if you need a lot of air-conditioning, you could save money. In my case, where the sun barely shines for nine months a year, 98% of my electricity comes from hydro, nuclear, and wind, I need no air-conditioning, and electricity rates are very low …solar panels make no sense at all; they won’t reduce CO2 emissions and they won’t save any money. Don’t tell my neighbors with solar panels that I said that.

There are other ways to consume more of the power you generate as it is being generated (send less electricity to grid) but they come with an escalating price tag.

Battery storage …forget about it.

You could have an electric and a gas version of all of your appliances, hot water heater, clothes dryer, and stove but would also have to use the electric versions when the sun is shining. You could drive an electric car but would have to charge it when the sun shines (instead of go to work in it).

If you have an unused place in a basement, you could install large, well-insulated water tanks to store water that has been chilled or heated with power from your solar panels during the day and then pump it through heat exchangers (radiators) into your home in the evening and at night.

It’s a common misconception that your solar panels somehow store on the grid the energy generated but not consumed by your house on any given sunny day. The energy isn’t stored. For a modest number of panels, the grid can handle the extra energy without having to reduce the output from a power plant just as it does not have to increase output from a power plant when you turn on your electric oven and clothes dryer at the same time.

I’ve always been a big fan of solar. Even though I realized long ago that solar where I live makes little sense from a cost or CO2 reduction perspective, I still liked the idea of using solar to eliminate that irritating monthly electric bill (by paying cash for a system up-front). But with the inevitable grid use fees, even that (maybe irrational) reason for having solar photovoltaic is lost to me! It’s somewhat frustrating that I ended up living in a place where solar photovoltaic makes no sense. Oh well.

The really cold reality is that residential energy use is a very small piece of the global energy/GHG pie. To wean modern economies off fossil fuels without doing things like destroying our last ecosystems by converting them into biofuel farms will take a massive, collective effort using every low carbon source of energy in our technological arsenal, including nuclear, starting with the most environmentally benign ones. An extensive recent study by the National Renewable Energy Lab which assumed no new nuclear power put the kibosh on the popular urban legend that renewables can do it all:

NRELResults2

  1. By Eric Dunn on February 5, 2014 at 10:15 am

    Your assumptions seem horribly wrong.

    Fuel may be “free” for hydro, but O&M, infrastructure amortization,
    and undoubtedly a number of other costs are quite significant. Even if O&M for hydro and other power sources is the same, your 12-9 exercise only gives fuel cost. It does not in any way separate out the infrastructure costs to get that power from A to B.

    Nor does it separate the issues of delivering the power and maintaining the power infrastructure.

    The article is thus a very poor guide to the future of infrastructure billing. It ignores the fact that in many places, infrastructure costs, fixed connection charges, and demand charges are ALREADY part of billing.

    There is no doubt that if solar becomes a dominant source that the cost per kWh of grid electricity might go up (fewer kWhs to amortize the construction and O&M costs) but it might go down. Owners of idle generators will want them put to use.

    It is not a simple situation and a simplistic article does the subject no service.

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    • By Russ Finley on February 6, 2014 at 9:55 pm

      My assumptions my seem horribly wrong to you …but your comment doesn’t make much sense to me.

      Fuel may be “free” for hydro, but O&M, infrastructure amortization, and
      undoubtedly a number of other costs are quite significant. Even if
      O&M for hydro and other power sources is the same, your 12-9
      exercise only gives fuel cost.

      Above, you draw the same conclusions I did.

      Nor does it separate the issues of delivering the power and maintaining the power infrastructure …It is not a simple situation and a simplistic article does the subject no service.

      The link I provided in the article is a good example of the complexity you speak of. See photo from that link below.

      The article is thus a very poor guide to the future of infrastructure
      billing.

      I would tend to agree, considering that it was never meant to be a “guide to the future of infrastructure
      billing.” It simply points out that solar panels will not eliminate electric bills for most people in the future and why.

      It ignores the fact that in many places, infrastructure costs,
      fixed connection charges, and demand charges are ALREADY part of
      billing.

      If I ignored that fact, how do you explain the link I provided to a real world example of someone with solar panels receiving a bill for those things?

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  2. By PBodine on February 7, 2014 at 3:09 pm

    Great article – the point at the end is an important one but took me a second to figure out. Having the legend for the NREL chart within the bracket “energy not supplied by renewables” made me scratch my head until I read the link to the other article. Still, a good point, and vitally important. You’ve probably already seen this chart from Livermore, but it is another (beautiful) way of making your point.

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    • By Russ Finley on February 7, 2014 at 9:41 pm

      I have seen that chart and thanks for sharing it. Below is a version that I modified for an article long ago …

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  3. By PBodine on February 7, 2014 at 3:10 pm

    Oops. Here’s the chart.

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  4. By PBodine on February 7, 2014 at 3:11 pm
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  5. By Peter McFerrin on February 11, 2014 at 3:07 pm

    The first “FAIL,” showing a solar farm on agricultural land, isn’t necessarily right. There’s a lot of former agricultural land here in California that’s already completely unusable for farming due to soil salination, inflicted during earlier periods in which flood irrigation was used. While there are a few crops that could be planted for remediation purposes, climate change is also going to mean that water is going to be a lot more expensive going forward; given the choice between remediating damaged land and irrigating those almond trees, a lot of farmers are going to choose the latter. Hence, the only useful thing to do with that land is to put solar panels on it.

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    • By Russ Finley on February 11, 2014 at 6:55 pm

      Good point. And that is my point also, we should not be covering arable land or land that is part of an intact ecosystem with solar …use brown sites, ruined farmland, rooftops. There is no shortage of land ruined by human industry.

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      • By Peter McFerrin on February 11, 2014 at 7:08 pm

        Yeah, but the Central Valley–which is where most of the ruined farmland can be found–isn’t the only place with high insolation. If the universe of acceptable places for solar can’t include any desert tortoise habitat, it’s going to be a very small one, and will be a huge competitive disadvantage for solar–which needs to be as cheap as possible if rapid retirement of the worst carbon emitters is going to be feasible.

        I work in demand response, and have faith in the ability of smart grid/grid edge/etc. innovations to make widespread distributed generation feasible, but DG isn’t going to power a central business district or a 10-megawatt water treatment plant. Utility-scale carbon-free power has to exist to a much greater extent than it does today.

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        • By Russ Finley on February 11, 2014 at 9:27 pm

          If the universe of acceptable places for solar can’t include any desert tortoise habitat, it’s going to be a very small one, and will be a huge competitive disadvantage for solar…

          Riiight. It’s listed as a threatened species because it’s population has declined about 90%. There may be more students in three Big Ten universities than there are desert tortoises on the Planet. A hundred thousand or so desert tortoises on Earth and you can’t find a place without them to put up solar?

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  6. By kristahiles on February 24, 2014 at 1:01 am

    This is absolutely correct information. I too help in installation of solar panels.

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