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Community and Q&A

Why solar since net metering is over?

Mike Kolder | Posted in General Questions on

In fact, in Iowa if HF669 and SF583 becomes law, utility companies would charge solar owners more each month because they have panels.  If your state still has net metering, I imagine it wont for long. California has already done away with net metering for new installations.

The only way to escape such insanity is to go off grid, or have only a portion of your home tied to the grid. 

So my question is, how would one split a homes electrical system in two parts, but be able to reconnect them if the laws change later?  And to also raise awareness the utility companies dont seem to want us to go green.  


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  1. Russell Miller | | #1

    Same situation here in West Virginia, it makes zero dollar sense to install solar. Now, i HAVE and will again soon but, our electric is cheap and excess production is dumped for no monetary benefit in return.

    Power outages, rare for us, environmental reasons are only reason to install solar here.

    1. diy_Nate | | #49

      Hi Russell. Nate here. I also live in WV. I live in the Huntington area. Do you have any good references for contractors that do home solar install.

  2. Eric Habegger | | #2

    California has not done away with net metering but they are finding that it needs to be somewhat micromanaged at the present level of greater deployment. In areas where there is already high levels of residential solar up to 3% or so of solar in summer goes to waste already. Your state is in a completely different situation where there isn't much excuse for what is happening to you. It always mystifies me when people vote for people for state government that will do something like this to you. There are always indications before hand how these people will vote BEFORE they get into office. I doubt that you are one of those people that get fooled but it seems many of your fellow residents are. People should do their homework before voting. It comes down to basic corruption of people in office that are beholden to monied interests.

    I've found a solution to your technical question that I've implemented for myself that seems to work. If you are interested email me at: [email protected]

  3. Mike Kolder | | #3

    From what Ive been told, only the older grandfathered systems still get net metering, not the new. This person who told me was angry about the electric car sticker and the lanes that you cant drive in unless its a new EV. He was going off about a bunch of other things like peak hour rates sky rocketing and immigration which made me feel lucky I didn't live there, but anyway. I'll send you a email soon.. Thanks

  4. Jon R | | #4

    I know someone who has some solar with no net metering (nor batteries) and never puts any energy into the grid. There are no technical barriers to having residential solar without net metering. With or without the grid for some power.

    If you want to use the utility as a battery, expect to pay for it. Compare the cost to regular batteries (expensive) and to thermal storage (can be pretty cheap).

    With utility scale solar (and wind) at about 1/2 the price, ultimately (most areas aren't there yet) there should be little reason for not-cost-effective residential scale solar. This is sound economic logic, not corruption.

  5. Expert Member
    Zephyr7 | | #5

    There are a number of legitimate reasons why the utilities don’t like net metering, and none of them have to do with profits or anything else economic in nature.

    If you have a grid tied system, see if you can configure it to never produce more than you consume on your own property. It’s only a technical problem for the utilities if you put power into the grid (“backwards”). If you vary between zero and some amount of load drawn from the utility you should be ok.

    Now if your utility is trying to charge you for having a solar system even if you don’t use it to inject power into the grid, then THAT I have a problem with. I’ve heard of utilities in the Virgin Islands doing that (they have unique issues down there), but nowhere else. If you’re in that situation, you may be able to use an automatic transfer switch (ATS) to switch between utility power and solar. Wire the ATS to run a subpanel that powers everything you want to run on your solar system. You would need to have the ATS switch between solar and utility power such that the loads would run on solar whenever the solar system had enough capacity available to run things. This would be similar to how backup generators are wired, but you’d be using the solar system instead of a generator. The ATS would allow you to run on solar or grid power depending on available solar capacity, but would never parallel the solar and grid systems. ATSes are approved for similar purposes, so this should eliminate any issues with the utility.


  6. Mike Kolder | | #6

    Since the bill isn't law yet, we maybe wasting time talking about this. But if HF669 and SF583 do becomes law in Iowa and other states, and the utility companies would charge solar owners MORE each month just because you produce electricity, I'm guessing they wont care if you have a ATS or just small control wire from you panels to their grid. Your still tied to it. What if your solar couldn't supply enough power on a cloudy day and your using both their grid power and your solar.. Or would the ATS disconnect the solar in that event?

    To me it sounds straight forward to go off grid and have twelve Rolls 4volt 1104 AH lead acid for 48volts at $900 each. Because then your free of the company who refuses to pay you back a fraction per kwh of what they charge you. Or charge you for feeding the grid so they can sell it without paying you. It is corrupt imo. They do this because there worried others will do the same.

    1. Expert Member
      Malcolm Taylor | | #7

      If you are willing to make the sacrifices going off grid entails - and Martin has often catalogued the trade-offs necessary - then fly at it. But I suspect for most people the principles at stake aren't important enough justify the lifestyle changes that would involve.

    2. Expert Member
      Zephyr7 | | #12

      They don’t like net metering because it causes unpredictable power flows and the system wasn’t really designed for distributed generation at the micro scale level. They aren’t really worried about homeowner solar systems hurting their bottom line, all of it together in most cases isn’t even enough for them to measure.

      An ATS will source power from either one or two sources, and those sources are NOT connected together EVER. You are not “grid tied” in this case, at least not in the usual meaning where “grid tied” means you’re paralleled with the grid. An ATS is like a switch, so in this case you would have a “grid” position and a “solar” position. Solar would never be connected to the grid, only your load would be.

      If a utility ever tried to charge more for rooftop solar with a setup using an ATS like I described, I think you could make a very good (winnable in court) argument that your system could not affect theirs and thus they have no jurisdiction over it.


      1. Jon R | | #13

        > all of it together in most cases isn’t even enough for them to measure.

        Not yet, but there are lots of examples of where it eventually became a big factor. Hawaii was late in taking action and it caused significant problems (technical and financial). Action should be taken now to prevent this in other areas.

        > If a utility ever tried to charge more for rooftop solar

        But it would be fully legal/logical to adopt mandatory time of use pricing - which would have a similar effect (since people with rooftop solar would use less grid power during hours when energy is cheap).

        1. Expert Member
          Zephyr7 | | #16

          Actually, it’s the other way around: solar output tends to peak right around peak load time on the grid (mid-afternoon(ish)). Solar is thus great for what is known as “peak shave”. This means with a “time of day” rate, people with solar setups would tend to use LESS power during peak load times when grid power is most expensive since their solar systems are at max production around the same time the grid is at max load. Peak load time is usually 11am to 7pm weekdays, or similar. This is the type of system I love: smart use of new technologies to accomplish something useful. Solar combined with an on-peak/off-peak grid pricing rate is probably the next best way to save money with a solar system if you can’t do net metering.

          Hawaii probably gets a lot of sun, similar to the southwestern US. That’s prime solar territory. I also imagine Hawaii doesn’t have a lot of heavy industry. If you’re in an area like the Midwest or northeast, there is both heavy industry and lots of cloudy days which means solar doesn’t have the same high average output capabilities as the same system would in one of the sunnier areas. In those areas, solar production is a tiny fraction of a percent of grid capacity (the ISO websites show the exact amounts). Iowa I believe is part of MISO if you want to see the generation mix stats.


          1. Expert Member
            Dana Dorsett | | #28

            >"Actually, it’s the other way around: solar output tends to peak right around peak load time on the grid (mid-afternoon(ish))."

            Peak grid load hours are highly variable with location, even when doing seasonal averaging. Peak loads on the CAISO grid ofent tends to be early to mid evening, well after solar peak production. In the ISO-New England grid it tends to be in the late afternoon. Only on high/very-high cooling load days does the peak load tend to be mid-afternoon-ish in either of those locations.

            Today's ISO-NE grid peak is projected to occur around 6:30 PM:


            (^this graph will change every day^)


            CAISO's grid peak yesterday was about 6PM, but today it's projected to occur at about 5:30:


            >"Hawaii probably gets a lot of sun, similar to the southwestern US. "

            Hawaii gets MORE sun than the southwestern US. Honolulu may have about a dozen fewer sunny days than Tucson, but on average has higher solar intensity due to it's lower (subtropical) latitude, and the more temperate peak temperatures yields higher PV efficiency during those sunnier hours. (For any particular location, consult PVWATTS: )

          2. Jon R | | #32

            > solar output tends to peak right around peak load time on the grid (mid-afternoon(ish))

            Almost never.

            Cost vs time (or conditions) completely depends, with now not being a good predictor of what instantaneous cost will look like in a future with the right amount of utility scale solar, wind and environmental damage accounting (we hope these will occur). For example, take a look at the the duck curve in California (peak load is when the sun isn't shining).

        2. Expert Member
          Dana Dorsett | | #26

          >"But it would be fully legal/logical to adopt mandatory time of use pricing - which would have a similar effect (since people with rooftop solar would use less grid power during hours when energy is cheap)."

          Whether "... mandatory time of use pricing..." is "...fully legal..." is not universal. Local regulations vary pretty widely on what & how rate structures may be applied. It might be fully legal in some places, but I suspect it's the exception rather than the rule in most of the US.

          Whether it's "...logical..." also varies pretty widely with location. For a more universal prescriptive it would be better for all involved to use dynamic pricing based in part on the LMP (Localized Marginal Price). Simple block time of use (TOU) rate structures are becoming useless in high variable-renewables penetration market. Whereas TOU made some sense to crudely modeling only the daily load curve averages, the VALUE model is much more complex when large amounts of variable output zero marginal cost generation is going onto the grid. The LMP reflects the real-time value of the power, and is a function of both the immediate load and the immediate variable output supply. When the LMP goes negative it costs variable output generators (and others) to keep exporting to the grid. When the LMP peaks the value of power exported to the grid can exceed residential retail block-TOU rates.

          1. Jon R | | #33

            Legal in the sense that it could be approved by regulators without a challenge that they would likely (I'm not a lawyer) lose if they tried to implement "we are going to charge you more for one thing because you own some other thing".

            Agreed, dynamic pricing is more accurate than time of use - but the latter works well enough for my point (discriminating against residential solar can be done even with "zero export").

  7. Kevin Henry | | #8

    To confirm what Eric said, California has not done away with net metering. They did introduce new rules, the effect of which is to credit energy inputs at less than the full retail rate. Very roughly speaking, if you purchase $1 worth of electricity you might only receive $0.90 of credit when you put that same amount of energy back into the grid.

    A decent summary of the rule change can be found here [1]. There's also an interesting paper that models the impact of the change on things like solar sizing and orientation [2].


  8. Mike Kolder | | #9

    Thanks Kevin. I'm embarrassed to have listened to and recited a disgruntled California resident now. I have no problem selling my electricity back at 10% less than I pay, or even more to maintain the grid. I got caught up in the hysteria of a "proposed" bill for my state.

    Did Martin ever write about his approach to his own off grid home?

    1. GBA Editor
  9. Tom May | | #11

    As Zephyr7 said, add a sub panel to dedicate a portion of your loads to be used with the solar. A small battery and inverter set up should be considered to keep things stable. Using an automatic switch may work but may also cause problems depending on the size of your solar system. A dump load, such as a water heater or electrical resistance heater should also be considered. A simple appropriate sized breaker attached to your main panel should be all you need to switch back and forth if necessary.

    1. Expert Member
      Malcolm Taylor | | #14

      Tom can you expand why a dump load is a good thing to incorporate? The engineers who installed the solar array at out local lighthouse did the same thing, but I don't understand the thinking behind it.

      1. Expert Member
        Zephyr7 | | #17

        A dump load is somewhere you pt any excess production from your solar system. If you can’t do net metering, where any excess production is effectively sold back to the grid, the next best thing is to use a dump load. In the case of a water heater, any excess production goes into heating water in the water heater: useful work. The alternative is to waste that excess production and do nothing with it. It’s always better to use the entire available energy output for maximum efficiency of the system. In the case of the water heater dump load, the water heater acts like a thermal battery, allowing any excess solar production to offset whatever energy would otherwise be used to make hot water.


        1. Expert Member
          Malcolm Taylor | | #18

          Thanks Bill.

  10. Jon R | | #15

    Switching loads between two circuits is definitely not a good way to achieve "zero export". You want a system that continually measures and adjusts power flow to never be negative (pushing power into the grid). Some inverters will now do this. Otherwise, a properly controlled dump load can achieve the same effect.

  11. Mike Kolder | | #19

    Martin's "How to Design an Off-Grid House" was educational and humbling when I read.. "off-grid electricity is expensive — on the order of $0.50 to $1.00 per kWh."

    Considering I have cheap rates at $.13 cents per kWh, PV's not cost effective. The article was written over 2 years ago, but I doubt the figures have dropped much especially with the tariffs?

  12. John Clark | | #20

    A friendly is almost impossible to sell a home is not tied to the grid at the time of sale.

  13. Mike Kolder | | #21

    I don't think that would be a huge deal to go back to the grid because there really isn't much difference between the electrical wiring in a conventional home and an off grid home. And I'm planning my retirement home so god willing, I'll be there for 20 years. I posted Martins numbers on solarpaneltalk and it's generated some back lash.

    Funny, I actually got a quote from the calculator at even though I stopped when I was asked how many contractors I wanted calling me. lol . The calculator said my price from mid america was .28 cents per kWh which is almost 3 times the actual price of .10 per kWh.

    Thanks for keeping things real Martin!

  14. Irene3 | | #22

    There's also the question of whether solar panels add to the value of your house, whether utility prices are likely to rise (one assumes they would at least go up with general inflation), and how dirty the power you would otherwise be using would be. The financial decision is something like buying an annuity: you put in a lump sum and "get back" (in a sense) whatever amount per year your electricity would have cost. Not too many annuities are indexed to inflation, but avoiding a utility cost is. A savings on utility payments is also tax-free.

    1. Tom May | | #23

      Which is why choosing off grid and ground mount is the better option. You can take it with you if and when you move.

      1. Expert Member
        Malcolm Taylor | | #24

        I'm a bit confused. if you lived off-grid and sold your house, why would you take your PV with you?

        1. Mike Kolder | | #25

          No, I own two properties. One in town, and one out in the sticks. I considered solar for my new property in the sticks which is in the planning stage. But my electric is so cheap, it’s not worth it. I just wanted to make awareness about these bills which might turn in the law. But I wonder why anybody in their right mind would buy solar with rates so low anyway.

          1. Expert Member
            Zephyr7 | | #27

            Rates vary depending on where you are. Some places are cheaper than others. SoCal, for example, has notoriously high electric rates and is also a place where solar works well. Other people choose to run solar for reasons other than absolute economic return. Offgridders are like homesteaders of old, making their own way in the wilderness.

            Just because solar might not make sense in your particular situation doesn’t mean it isn’t a good option for someone else with different requirements.


          2. Irene3 | | #29

            You might want to consider at least planning an orientation that would be good for adding solar later (e.g., having a nice big patch of roof to the south). It's entirely possible that in twenty or thirty years' time solar will become an expected or at least very common attribute. And goodness knows the energy landscape could be completely different by then.

  15. user-7514453 | | #30

    As a new RAV4 hybrid owner, I now better understand normalization of energy usage. I've always been interested in a partial off grid for one or two mini splits to lower the monthly bill. Really need thoughts on battery or capacitor to avoid peak usage surges as well as automated grid on \ grid off switching that's wife friendly and zero maintenance. Of course I want to dump excess to water heater i.e. preheating in small tank before heating with NG. Small targeted installs around the house would seem beneficial in a few ways ??

    1. Eric Habegger | | #31

      This subject is worthy of a blog post in itself so I expect my reply will be long. It's a big and interesting subject so please forgive me here.

      I live in the California where we have time of use billing with the more extreme versions being optional to the customer. I've selected the most extreme form. PG&E calls them "Smart Days" under my plan, which are days when electricity goes to 60 cents per KWhour from 2 to 7 PM. These days are call by the utility when it is forecast to be extremely hot. Usual billing in summer is also tiered higher than non-summer at 25 to 33 cents per KWH.

      I didn't need a big solar battery system to compensate for this as I don't use air conditioning (just a whole house fan and a tight house). I do need ceiling fans, an ERV, and power for refrigerator that I would like to put on a small solar power system during high TOU rates. We also will start having planned power outages by PG&E on windy high fire danger days. Together those conditions warrant a small independent solar battery backup system that can be independent of the grid.

      For my needs all I need is a solar generator, something new on the market that is primarily used for emergencies and for camping. I'm not recommending a specific model but for my use I selected a Goal Zero Yeti 1400 KWH solar generator. Basically a solar generator is a battery, inverter and charge controller in one small modular unit. I wired it into a Reliance Home Integration Unit. I modified it so that the standard short connection to the service panel is greatly extended. The HIU now sits in my kitchen, along with the solar generator, and I manually select which of 4 circuits ( refrigerator, lights - ERV, microwave, and small appliance circuit) is run by the solar generator or the grid.

      I just started using It an it works really well and I use it to time shift my use of power from high cost TOU to low cost TOU. I also will use it as backup power when PG&E shuts down power for any reason.

      I'm very handy with electricity and electronics of any kind so this made a lot of sense to me and I did the wiring and modifications all myself. I would expect someone hiring a person to do the wiring and remote location stuff might pay an arm and a leg for that. But for me the expense of everything was just over 2500$ including the low voltage PV panels. Plus its very easy to take the portable solar generator out of the home and use it for camping. Since the PV panels are low voltage and the home integration kit maintains isolation from the grid no matter the switch positions there is no permit or notification required to the local utility.

      It's important to understand that when those 4 circuits are switched back to grid supplied it means that if you have a net metered grid tied solar system installed later those circuits will be supplied by that system and not the solar generator with those switches in grid tied position.. One can have those 4 circuits supplied by net metered or by the solar generator at your whim. You really aren't limiting the size of the net metered solar system. There is only one caveat to that: the low voltage PV panels can't be used in the net metered high voltage system. In other words, don't overdue the size of the battery backup system besides using it just for "supplemental reasons" that I outlined.

  16. Mike Kolder | | #34

    Morning people..
    I got a letter back from my state rep..

    "Dear Mike, I am and will continue to fight this legislation.(HF669 and SF583) We were able to stop it last year and will continue our efforts again this year. Mary Mascher , State Rep."

    But after reading Martins statement "Off-grid homeowners have a much stricter energy budget than owners of grid-connected homes. This is due to simple economics: off-grid electricity is expensive — on the order of $0.50 to $1.00 per kWh." and deciding PV was to expensive for me.. It was under the assumption that HF669 and SF583 Would pass. If HF669 and SF583 did Not become law, how much less would buying and installing grid-connected PV be without the batteries and gear needed for Off-grid and given the current net metering policies?

    After trying to understand the last link, its apparent I'm not sharpest tool in the shed. But I still doubt PV could ever compete with the $0.13 per kWh I'm paying now, even if I installed the PV myself and then hired a professional to wire it.


  17. Tyler Keniston | | #35

    Would anyone be willing to briefly touch on some of the non-economic reasons utilities don't like net-metering and/or distributed residential solar generation? (perhaps Bill or Jon, who've made mention of such?)

    The only technical issue I am aware of is the backfeeding issue when power would otherwise be cut. (true for generators too though).
    Is there some sort of power management issue?

    1. Expert Member
      Zephyr7 | | #36

      There are issues with power factor correction and reactive loading. AC power is not like DC. With DC power, there is voltage and current, multiply the two together to get watts. When you draw power, there is only current. Hopefully that makes sense, I’d really like a whiteboard to explain this kind of thing. Losses are just based on however much current a load draws and the resistance in the wiring.

      With AC power, you have voltage, current, frequency and the concept of “reactive” power which can be thought of like imaginary power. Since AC power is a sinewave with a constantly changing voltage, loading depends also on “how” your load draws the power. Think of two overlaid sinewaves with one trailing the other. If the trailing sinewave is the current of the load, you see that the current peaks at something less than the voltage peak from the first sinewave. This is known as “lagging power factor”. The problem is you have a higher current for the same delivered power which means more losses in the wiring for the same amount of delivered energy.

      Utilities don’t want increased system losses.

      For small scale systems, this little bit of extra variability doesn’t really do anything. For larger scale deployments (like Southern California), you end up with some issues with power flows since the distribution network was never designed with this in mind — electric SUPPLIES are generally connected at the transmission level (big 120+kv lines).

      If you want to do some more reading, you’re looking for articles about electrical grids and frequency stability as well as distributed generation. There is a lot of info out there.


      1. Tyler Keniston | | #37

        Thanks Bill,
        That makes perfect sense. Thanks for the research leads. You are right that there is lots of interesting reading on this.

        One of the discussed solutions that seems really interesting are the smart inverters that can purportedly form grid stability (contribute to) rather than follow and interrupt stability.
        Another article touted ultracapacitors as possible leveling banks.
        I've also wondered if DC links could help stabilize.

        I'm sure there won't be one answer, but it's fascinating to consider how we might problem solve such an energy transition, and how the technical problems with shape its future.

        1. Expert Member
          Zephyr7 | | #39

          Yeah, it’s possible for inverters to perform some grid support functions. The difficulty is remotely controlling them. In the utility world, this is known as “dispatch”. Utilities like to run the cheapest generation the most, and bring additional generation online in order from cheapest to most expensive to support additional load. This is the primary reason the independent system operators (MISO, PJM, etc) were formed.

          There are some DC interconnections already operating, and they allow for much greater control over power flows. Some examples are the “highgate converter” in the northeast, and the pacific DC intertie (path 65). The pacific DC system is actually one of the earliest major power transmission projects in the US that could be considered as part of a “smart grid” and it was done to improve efficiency through the pacific states. It is a very interesting project.

          Solar has the ability to help reduce the need for what is known as “spinning reserve” and improve system efficiency in that way. Max solar output occurs pretty close to max grid load.

          I’m not sure if ultracapacitors hold much promise here since their overall energy storage capacity is limited.

          BTW, there is some effort underway to improve the communications and control functionality of the power grid. The next time you see some transmission lines — the big ones on steel towers —- look at the two wires at the very top (the “static shield” wires). They will be smaller than the other three or six (for a single or double circuit transmission path, respectively). If one of those two is fatter or shinier than the other, look at the support (known as a “trunion”) where the wire attaches to the tower. If one is bigger than the other, or has spiral spring-like assemblies on either side, then that wire is most likely what is known as an “optical ground” wire. Most of the strands in such a cable are aluminum or steel, but one or more will be stainless steel tubes with fiber optic strands inside. It is a clever technology (AFL is a major manufacturer of the cable), and is being used to upgrade the grid control systems from the older carrier current systems. The resulting greatly increased communications capabilities will enable future smart grid functionality.


          1. vap0rtranz | | #40

            Seems there are a lot of Elec Grid haters on GBA, as if the utilities are not genuinely changing.

            Because of a previous life, I know some of the smart folks working on the Hot Springs microgrid being done by Duke, GE Energy, Itron, etc.

            It doesn't take a rocket scientist to understand that residential/commercial solar onsites introduced a fundamental shift in electric generation and distribution, with the current problem being how to scale onsite generation to more than just a few Green Energy fans. In sum, the shift is:

            FROM: central power plant generation via grid distribution (and no storage)
            TO: distributed "cell" generation via microgrid (with energy storage)

            Just on the technology side of the house (b/c that's all I was involved in), the utilities needed to develop systems that could manage the shift to the latter, sometimes called DER (Distributed Energy Resources), like your onsite solar and battery bank. Folks here seem to have an idea of what those challenges would be -- the usual suspects: relaying Voltage, Frequency; but the key changes are (a) how to switch to onsite storage, (b) how to prevent "islanding"*. There are 2 new standard technologies to get at this: one being OpenFMB, the other I cannot recall it's name but is sponsored by PG&E's R&D teams in Cali, if I remember correctly. OpenFMB's site has more info for those demanding "what's the hold-up? whatcha' doing about it?":

            If you have ideas, other than Elec Utility hate, then there are several organizations that you can contribute to, like NAESB, SEPA, etc.

            * islanding was a huge concern that I heard during these meetings. One scenario: onsite generation is off (so no sun at a solar site), onsite energy storage is exhausted (batteries low), so how to manage pulling power from elsewhere so the microgrid doesn't go offline? and vice versa: how to pull excess power from microgrids so other cells won't go offline. The old Grid seems to be able to handle the oddball solar array homeowner but the concerns were how to do this at scale, i.e. if every home gets a solar roof + power pack. I remember engineers talking about all the blips, frequency / phase compensation, etc. to get offsite generation back online for a microgrids that would need power. Above my head -- those power EE guys have lots to consider.

          2. Expert Member
            Zephyr7 | | #41

            Islanding has always been a concern, even with conventional generation. An “interconnection” is a network — a power grid — where all generations are synchronous, which means all their output sinewaves are locked together in-phase. The grid then looks like a single, massive power source with lots of paralleled generators.

            Now imagine you have some major storms that chop up a bunch of the major transmission lines interconnecting the grid. You get “Islands” that are small (relatively) chunks of power grid with a generator or two and some load. If the load and generation are matched, the island is stable. If they aren’t matched, you get system collapse. All of these islands will than drift out of sync with each other.

            The issue has always been how to bring multiple islands back into sync with each other. AC power flows from areas of high frequency to areas of low frequency so these synchronization issues are a major concern for system stability.


          3. John Heckendorn | | #42

            @Zephyr7 and @vaportranz: Do you see these issues driving a push by the authorities -- be they government, regulatory agencies, utilities (maybe all in lockstep) -- to centrally manage what are now individually-owned and -operated residential and commercial PV installations? Could definitely envision this happening in California as the footprint of distributed solar (and perhaps wind, in some locations) becomes wide and deep over the next few years. Don't know how or if they'd compensate current owners, but could be very controversial.

          4. Expert Member
            Zephyr7 | | #43


            I don’t see any immediate push for regulatory action, but it’s difficult to predict the future. Any such regulatory push would like originate at the NERC, probably at the urging of one or more utility companies or ISOs if they start to see large enough power swings to get worried. My guess would be any first steps would be similar to what is required for interconnection of any other “independent power producers” (IPPs), and that is for a method for the system operator to remotely disconnect any third party generation from the grid if needed.

            Future stuff might be for the solar inverters to be able to talk to some kind of network so that the ISOs could actually see the power parameters for the distributed systems. That would also allow remote control, which would solve most of the issues with unpredictable power flows. There will likely be some pushback from solar owners because “the man” can now remotely control their systems a little, but in this case some remote control is pretty important.

            I can tell you that the ability of the ISOs to integrate some of these kinds of things into their systems has improved in recent years. Telemetry networks on the power grids are getting MUCH better than they used to be. Fiber optic systems are far more capable than the old carrier current systems.


          5. vap0rtranz | | #44

            @Zephry7 & @John_Heckendorn

            >I don’t see any immediate push for regulatory action,

            It's already happening. What's this rule that only authorized installers can setup a homeowner's solar system to be grid tied? And only State approved inverters (as is the case in my State) can be installed. That is indeed regulation to some extent, even if some of us think it's a good idea.

            >Future stuff might be for the solar inverters to be able to talk to some kind of network so that the ISOs could actually see the power parameters for the distributed systems. That would also allow remote control, which would solve most of the issues with unpredictable power flows.

            That future is already developed. It's what OpenFMB was developed for and approved by NAESB to do.

            >Telemetry networks on the power grids are getting MUCH better than they used to be. Fiber optic systems are far more capable than the old carrier current systems.

            Fiber bandwidth doesn't have much to do with this, even if serial comms in telemetry or C&C systems is slower than fiber; but I assume you mean out-of-band management technologies that over time replaced in-band (in-circuit) systems.

            The bulk of the current control/C&C, management, and telemetry systems are all SCADA based with implementations like Modbus and DNP3, and those management systems were designed in the 70's and 80's with the idea of a central grid, aka. physically secure systems, all components managed by a utility, systems that implicitly trusted each other, etc. Sure those SCADA systems weren't on fiber, most were serial, but that's really besides the point. Microgrids and grid tied solar introduce components that are DEcentralized and potentially NOT owned by the utility, aka. a homeowner's solar inverters. That introduces unique challenges beyond islanding. (In the above, I wasn't saying that islanding was the only concern.) That's in addition to the management systems communicating new payloads of datasets that the previous generation of C&C systems simply didn't relay, like the state of charge of battery banks.

            Another huge concern that came up in meetings was how to secure DER systems b/c of the loss of traditional security (physical proximity, utility owned, etc.). On homeowner's sites, the new architecture looses physical security almost entirely, or is proxied to us. Then you're relying on responsible homeowners to manage a component of a microgrid that can create a domino affect. I mean, how many homeowners are going to install barbed wire fencing and security cameras pointed at their inverter? like we see at substations. AND let the utilities snoop in to monitor their setup? No way. More subtle questions remain to be figured out. For example, will remote monitoring (and possibly C&C) be communicated to/from a so-called "smart" inverter via the homeowner's Internet? or will utilities add a dedicated comms line to each home? Piggy backing over a consumer grade ISP has all sorts of issues, from performance, reliability, and again security. Even a rogue actor trying to inject incorrect data onto a microgrid comms channel came up as a scenario, which could happen if a homeowner's Wifi or home network that a smart inverter is piggy backing off of is compromised. The previous generation of technologies, so Modbus, DNP3, etc. couldn't really be extended anymore to cover the DER use case.

            I think this is why you're curious about regulation. How much of a burden will be placed on homeowners? Let's say we only allow authorized installation of a homeowner's solar inverter (as is the case in my State). Like I said above, that is the 1st kind of regulation that I've noticed being placed on homeowners as a "burden", but there doesn't seem to be much push back on that.

            It does look like we're going to have a different ask of homeowners' properties than in the past, when we were all just required to let utilities "take a reading" of our meters; so that means new regulation.

          6. Expert Member
            Zephyr7 | | #46

            There have probably been some issues with self-installed grid tied systems causing problems. This isn't much different from requiring electrical work to be done by licensed electricians. I haven't heard of the utility industry pushing for this though, so it the "authorized installers" stuff might be from cities or the state. Either way, this will probably vary state by state.

            Regarding the telemtry networks, putting in the foundation for more data transport is the first step to enabling future services. The original telemetry systems were very limited in how much data they could move, which limited what could be done with them. The newer systems have much more capacity that will allow a lot more to be integrated in the future. I do hope the newer systems maintain the reliability of the older modbus systems. More complexity does invite more problems.

            My thinking was more along the lines of what the underlying systems would need to be able to do to enable real distributed functionality, not so much how government entities would try to make sure certain rules and procedures are followed (licensed installers, etc.).

            >"Another huge concern that came up in meetings was how to secure DER systems b/c of the loss of traditional security (physical proximity, utility owned, etc.). "

            In this case, I think the security aspect isn't as important. If some nutjob wants to wipe out the grid, messing with a few multi kilowatt residential solar systems just isn't going to do anything -- they're too small. Statistics helps you here: you would need to cause trouble with so many of the small systems that it would be very difficult to get the scale needed to cause any real problems for the grid. Any real security would be needed at the controlling end of things, which would still be under the utility's control. A few little systems here and there acting up or dropping offline won't destabilize the entire grid, since the grid is VASTLY larger than the small, distributed solar systems are.


    2. Expert Member
      Dana Dorsett | | #38

      >"Would anyone be willing to briefly touch on some of the non-economic reasons utilities don't like net-metering and/or distributed residential solar generation? "

      Anything that they can't directly measure or control becomes a modeling & guessing game for the utilities, adding a layer of complexity to the load forecasting or even what peak loads to design for on the distribution grid.

      PV inverters have become more sophisticated over the past decade though, and can be set up to deliver some amount of power factor correction or over/under voltage conditions on the local grid, delivering some amount of support services even when not directly under utility control. With more direct control given to an aggregator or utility distributed PV has the capability of providing all sorts of grid-services at a lower cost than traditional methods (at least while the sun is shining), when operated as "virtual powerplant", in much the same way that it's being done in some cases using utility-scale PV.

      Depending on the regulatory environment & level of integration utilities can either gain or lose (financially & control-wise) by having a large amount of distributed resources on their local grid.

  18. Jonathan Rupp | | #45

    I have 2, 100w solar panels without a net metering contract (outside boston with 0.23C / whr electric costs). I sized the solar to produce the minimum power my house uses. I have a very shaded lot, so i wanted to see how much power the solar would actually produce over a year before spending more on a larger system. We like living surrounded by trees, so we have no intention of cutting down trees for solar.

    Peak summer on a sunny day, I get about 2 hours a day of direct full sun on the panels (producing 150-200 W), and then they produce up to ~50W for the rest of the day. June and July peaked around 550 whr of power / day. Overall i am track for about $10 of electricity generation (adjusting for a few months when the panels were still on the ground getting less sun). Not a whole lot, but considering the whole setup cost a little more than $200 post tax incentives, that is a rate of return a little over 4% - much better than short term treasury bonds.

    The 150W nearly perfectly offset my house consumption during the day (we both work so it is just things like the refrigerator, internet routers, smoke detectors, etc. But now that we have a kid, that has gone up and i'll probably add another panel or two .

    I've been using Legion solar product from PLX, which monitors the power on the mains, and starts to turn off the inverter when you hit 0W over the mains. Overall, we're happy with it, but having lots of shading limits the time it is at full power, and not being on net metering limits the size of the system, and given our sun constraints, i cant get the payback on a battery to work

  19. Eric Habegger | | #47

    I've been mulling over the many thoughtful comments here and also learning about the different technologies involved in Distributed Energy Resources on the grid. After thinking about this I've come to a conclusion that might not be apparent even to the experts here: There is good reason to divide DER into two segments, power generation and storage generation.

    Non-utility level power generation is already very well understood and implemented, even at the residential level. Most home inverters, especially the microinverters similar to Enphase makes, are well understood and tested to be compatible with the power requirements of utilities. They have to be to pass regulations in my home state. Other states may not be as stringent on their requirements to pass certifications which may be a problem for local utilities. The most popular used inverters like Enphase's have already provided a solution that works. In fact, they are a separate distributed energy resource wholly existing within a single residence. If one microinverter goes down it automatically isolates itself and the others try to fill in. There is very little likelihood that a single residence with microinverters brings down a microgrid in a neighborhood.

    It is also quite easy and foolproof to install a system with microinverters. This is where I think states like Florida are failing their residents. It is clear to me that the utilities in that state are trying to conflate the difficulty and unreliability of some kinds of inverters with known reliable solutions that are out there. In other words, states like Florida are in the pocket of utilities to try to confuse customers and are making it very difficult for homeowners to get grid tied solar at a reasonable cost of equipment and labor. This is what I was speaking of when I said lawmakers in local jurisdictions are corrupt and bought off by some utilities. It's real and it exists. DER is no longer rocket science and there are reliable solutions that can be implemented by the homeowner without paying an arm and a leg. Also those solutions, especially the microinverter types, have well tested software programs that will only allow it to be online with the grid if they pass that algorithm.

    Distributed storage systems that are connected to the grid should really be considered a different animal from distributed power. In my opinion distributed storage that is grid connected at the residential level has no place in the modern infrastructure. It really doesn't benefit the homeowner and seems to be a nightmare to develop the communications required to monitor individual level of charge at individual homes and then have a central utility manage it.

    Batteries are expensive and it just makes much more sense for the utility to possess them to level their loads and to use them to replace peaker plants. Batteries have their place in individual homes, just like I have mine. But I control it and it is isolated from the grid. I would never have enough money and resources to have enough batteries to supply AC, water heaters, and range/ovens. It is just uneconomical for the foreseeable future. Better to have the utilities own them, control them, and have the population pay for them as a percentage of their total use of energy. That is the most efficient and fair way to go about implementing storage into the grid.

    1. Eric Habegger | | #48

      Here is a not so recent article about what's up with Florida. Enjoy.

      1. Expert Member
        Zephyr7 | | #50

        That’s a pretty slanted article.

        Most of the utilities legitimate issues with grid tied solar are with system stability (potential for weird and unpredictable power flows, etc), and with covering the costs for the distribution network — the power lines — when they net metering essentially cancels out a chunk of the revenue that would normally support the system. This issue with covering the distribution network is very real: if you use net metering to essentially replace your battery, you’re using the system in way that doesn’t work out financially with current regulations. Yes, that is something that can and should be fixed. The issue is how to do it? The likely solution is higher costs for grid tie kwh compared to “regular” utility sourced kwh. Solar owners might not like that, but it really is fair.

        Just about every company has lobbyists. That’s an unfortunate reality of the current world. It doesn’t make them evil, and some of the things they lobby for are legitimate issues. It is a fact that many in the green energy world don’t understand the realities of large-scale power systems and try to regulate/mandate impractical things, or things with major downsides. The utilities fight fallacies too.

        There ARE some issues though. Florida’s regulatory issues pale in comparison to those in the Virgin Islands. I most certainly do not like the idea of being charged to own solar even if not grid connected. In Florida, I wonder about the insurance requirements. Basic structure damage should be part of the homeowner’s regular policy. If the utilities are trying to require some kind of commercial policy that seems odd to me. I deal with that at work, where we have to maintain a very large ($10 mil, and by contract we can be required to go up to $30 mil at any time) liability policy, but we work on the poles and own equipment on the poles. The utility legal guys told me they require enough insurance coverage from us (and other pole tenants like Verizon, etc) to cover the power co’s deductible. They just don’t want any liability. I don’t know how or why that would extend to homeowners equipment installed on their own premises though.

        Most of the pushback from utilities is actually legitimate. In my state, there is a law about selling kwh of you’re not a utility, unless the utility oks it. This has never been extended to residential solar though — its intent is to prevent unregulated black-market style power cos from popping up. The utilities have other issues to worry about, and just because the other side doesn’t understand them doesn’t mean they’re against things. Remember that utilities are generally legally obligated to provide service to everyone at certain levels of reliability, so they have to be concerned with anything that puts their ability to do that at risk.

        Some of the stuff in that article about percentages of power from renewable sources seems odd to me too. The state with the highest amount of wind generation in their mix according to their ISO’s real time stats is Texas. They dwarf all the other ISOs. The total amount obviously varies with weather conditions, but I’ve seen it up around 17GW or so. Most of the ISOs show total combined renewables output as something of a few percent or less of total system generation.


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