grid tied solar systems

Grid-Tied Solar Systems Don’t Work Well When The Grid Is Down

This may be a surprise. A typical grid tied solar system will not provide power for your home when the sun goes down, or, if and when the electric grid goes down.

I’ll bet that countless thousands discovered this recently when California’s power utility decided to shut down the electrical grid due to wind/fire danger hazards. Whoops… Most homes with a grid tied system lost their power too, even though they had solar panels on the roof!

However, read on for more information how to overcome this…

Grid-tied systems make up the vast majority of solar power system installations. As opposed to off-grid.

What is a Grid-Tied System?

In short, solar panels are tied (plugged) into the electrical grid through a grid-tied inverter.

A system called “net metering” will, in effect, roll your power meter backwards as excess energy from the panels feed into the grid.

When the home requires more energy than the solar panels can deliver, you draw electricity from the grid instead.

In essence you get credit from the power company as your grid-tied solar system dumps energy into the grid. But then that credit flips the other way when your energy demands exceed the panel’s output.

So what’s the problem with that? (you might ask)

The Problem With Grid-Tied Systems

There’s not a problem for most people, most of the time. Why? Because most people install this system with the expectation of saving some money over the long term. The net-metering billing system simply works behind the scenes and adjusts the monthly electric utility bill accordingly.

The Surprise

The problem arises when the electric grid goes down. Perhaps storm damage or some other reason. The homeowner discovers that there’s no power. Even though there’s lots of solar panels on a sunny day.

It’s a safety issue. Grid-tie inverters will switch out of the grid when the grid itself goes down. This is necessary for safety reasons so as not to injure a utility lineman with voltage back-feeding from your solar system into the grid while the grid itself is down.

Some Grid-Tied Inverters Have Courtesy Power

With that said, some grid-tie inverters may have an attached outlet providing “some” limited power for use while the grid is down. For example an extension cord could be plugged into it and power routed to a chest freezer or other appliance, etc.

Of course the sun would have to be shining for this to work.

Grid Tied AND Off-Grid Capability

The best of both worlds? A charger / inverter designed for both grid-tie and battery storage energy. Depending on your arrangement with your utility, you’ll get credit on the utility bill for energy fed into the grid, while also having energy storage capability for grid-down scenarios.

The problem with this is the expense. It costs lots more to do this. Because of the battery cost. However it is in an option. A battery bank. A better charger / inverter, interconnections and installation.

One of the best out there (in my opinion) is from Sol-Ark. You might check out their charger / inverter.

Sol-Ark

Off-Grid Circuits

This is not for everyone. But briefly, this is how I have my system installed…

I do have grid power to my home. I’ve also installed a stand-alone off-grid system which I use on various circuits within the home. I separate those circuits completely from the grid by way of transfer switches. Fortunately I have the knowledge and experience to have done this myself (saved installation money). But I’m just putting the notion out there for anyone’s interest.

The battery storage bank is always a very significant expense. If you plan on staying at your location for a significant period of time, the long term cost analysis is less painful. And in fact, it seems that today’s current Lithium battery technology provides reasonable cost over the life expectancy of the battery type.

The Takeaway

In summary, I just wanted to get an article out there which briefly describes the basic functionality of the very common grid-tied solar system. It works great when the sun is shining. But not so much on cloudy days, and not at all during the night. That’s when you still need the grid. Additionally, when the grid goes down, so will most grid-tied solar systems.

[ Read: 4 Essentials of Off-Grid Solar ]

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45 Comments

  1. New construction laws in CA require a Solar Power System be installed on new home construction. At an average cost of $10-$15K
    They failed to inform the owners of exactly what you stated above. Most believed the system would power their homes If/When….. Guess not huh?
    Do your homework people, Life is not that hard if you use that Gary Mater.

    1. Also, California requires solar systems (solar plus battery system) must be tied to the grid (Title 24).

      Title 24 came about because CA was afraid that too many residents would get their solar system and leave the electric power grid, so CA has forced residents to be anchored into their antiquated electric grid. It’s my understanding that a stand-alone solar system w/out batteries is not forced onto the grid….

      So once again, California screws their residents, even the climate-alarmists, six ways to Sunday.

      1. MT
        Of course they screw them,

        It has nothing to do with anything other than government control

        Period

  2. A friend of mine has a grid tied system, it has a “backup battery”
    The weird part is that the battery is only a UPS type setup that provides power for about an hour then shuts down, the panels dont actually charge the battery, grid has to be up for that, screwy deal, it cost him big bucks and he was pissed to find its not a true battery backup

  3. It started long before the CA required the tie in back to PG&E. Notice how close those to are, almost as if they are kissing cousins.

    PG&E set restrictions back in 2003-04 of what type of box for relaying the power generated by your panels you could purchase. We wanted the power produced by our panels into a battery bank so when & if the power went down acdh & would have power without having to fire up the generator. OH,,,no PG&E would not let the companies sell those units to their customers. A neighbor who is off grid tried to purchase them through his distributers for our usage, sorry they are no longer available for your area.
    We were stuck with the units sending power back to PG&E, and when we did this it was not cheap. Are they paying for themselves, I doubt it!

    With the cost of power, what they charge the consumer and what they give as credits to those with panels is a wide margin. You are losing money for that large of an investment-“a fool and his money shall be quickly parted”. 💵💸 That is what comes to mind. mho

    Oh, ours have to be replaced due to hail damage from a freak storm. 😣😫

  4. He should have called takl……….all jokes aside, that’s the tried and true method mother nature put in place for us to learn. Learn from mistakes. Sadly, lots of people did not sign up for that class.

    Why did your friend not seek advice from you?

  5. I don’t personally know anyone who has a grid-tied system. So I’m not aware of the net-metering billing situation. People may think that the utility company will credit for the same price that you’re paying (per kWh). However it’s likely that they credit much less per kWh than what you otherwise pay.

    For example, if one’s cost per kWh is say, 12 cents (the price you pay the utility), then I’ll bet they might only credit you for something like 6 cents per kWh when you’re dumping energy into the grid?

    Does anyone have a real example out there of how much they credit back per kilowatt hour? (just curious)

    1. Ken
      You probably have the rate we are receiving for our panels. Those without panels, their power rates are double of what we pay. We have what is called a ‘true up period’. At the end of the year all your charges will come due so I pay money monthly to keep from being hit with a large bill at that time. Evan with the panels our electrical bill averages per year $2,000 to 2,400, on this property, and our heating is propane, so is our cooking stove.
      We are charged extra for not having one of their smart(dumb)meters on the panel box. It is to close to the house, and with all the harmful data that I have read is another reason why I refuse to let them stick one on our property. Dislike all their controls on what we can & can not do.

        1. Susie, in some areas you could get a medical waiver, and in other areas you could bypass it with an additional fee tacked on to your bill. For reading the meter, supposedly.

        2. Susie
          Yes we did.
          Commie state of fruit & lots of loons under the PUC gave those who did not want the smart meter a choice but at a price. Of course. They want us to pay a small fee for the employee who has to read our meter, which has grown over the years from $5 to $15 a month.

          The smart meter started with the normal electrical panel, then they figured out a way to include those who installed solar panels.

          Believe it was Nevada when the homeowners were at work they would enter the property and change the meter without prior notice.

          Lot of angry people when they discovered what had occurred. They wanted those boxes off, and the electrical company said sure, but of course ‘at a price’. In some places they were charging over $50 just to take it off and put back a similar meter of what was originally on their panel.
          All about control.

    2. Ken;
      In my area we actually have two “Power” companies, one is 10 the size of the other, will not allow “Buy-Back” metering, the other does, I’m lucky enough to be on the Buy-Back company.
      Have done quite the research, and have found that actually setting up a full “Battery & Generator Backup / Grid Tied Buy-Back system is not really that difficult, one just needs to basically install a ATS (Automatic Transfer Switch) Split the Panel, and have a Priority Switch (switch from Battery to Gen).
      I finally got all the pieces figured and OKed by the Electrical Inspectors AND the Local Power Co. All I need now is the $$$$ Around $20K for all the Good Stuff.

      So to answer your question, the Local Boys are Buying-Back at 80% or 80¢ on the Dollar.
      BUT you have to have a Buy “Back Meter” aka “Smart Meter”. And allow inspections of the Install by the Power Co. and Electrical Inspector.

    3. Ken,

      We don’t have a solar system here on the farm, but I checked our small rural electric company here in western Colorado about grid-tied systems. They use “net metering” and any excess you generate is added to your “bank” for use during the year. At the end of the year if it appears you generated more than you took off the grid ( positive “bank account balance”), they will reimburse you for those extra generated KWH you put in. But, those KWH are compensated for at a rate of “avoided cost of power” and is subject to a minimum. The “avoided cost of power” is not defined in their literature. Given that they buy power off the grid, but also generate power from both solar and hydro, they could apply any of those rates to your payback. What do you bet they pay you back with the cheaper of the bunch???

      1. I looked into grid-tied at some point in the past. It was too restrictive at the time. then I had to go back and ask myself, ” What is my purpose for going solar?” the answer was I wanted a ‘stand alone back-up system’ of power. OK, that means a stand alone system with a battery bank. Like NRP, I will do it when I can save up the bucks. I will likely design a very small system to start, with the ability to expand it as money allows.

    4. I got to briefly look over a friend’s contract, and the letter sent to her stating the differences in the NEW contracts if she got her system installed after a certain date.

      Essentially (under the “new” contract) you are credited the amount that it would cost the utility to generate that amount of energy. So if it costs them $.01 to generate a kw of power, you get credited that amount. This is still good if the panels can provide most of your energy.

      Prior, it was 1-1, kw in and out. So if you produced 10 kw and used 5, you got a credit of 5 kw (at that time $.11 per kwh) although there was some kind of weird calculation involved that brought the price down slightly.

      So the electric company pushed for solar, then when people were committed they changed the contract.

    5. Not all states require net metering. In my area if you have a grid tied solar power system the local power company must sign off on the installation due to safety issues, so far Okay. Now you get your bill from the power company on one meter and a separate meter measures what you send back to the grid. The price you get is the “avoided” cost. This might be negative depending on the time of day and season and then you owe the power company for what you sent them or at best a much lesser amount than what you paid. Cool huh?

      This is why I have stand alone solar as a “generator” for emergencies. The cost is not recoverable but I have some peace of mind.

    6. Here in Cali, PG&E is charging over 30 cents per kWh at peak but paying less than 4 cents for credits at true-up. But by avoiding those extremely high energy rates my grid-tied rooftop PV system has about 4 years ROI (not accounting for grid being down for extended periods).

  6. AC

    Are you not allowed to do an off grid system that would supply critical circuits by way of transfer switches? Perhaps your location would be great for separate circuits only powered by solar and a generator when needed. Then the grid would only serve part of your needs and be totally separate from that dictatorial outfit. Adjacent States may have the equipment if not locally available.

    1. hermit us
      As we recall the answer was NO at the time we did this. We really wanted the battery back with the transfer switch. We had purchased all the parts for the system we wanted but then came the resounding SORRY no longer allowed in this state. We still have the transfer unit for an off grid/grid system.

      If we had purchased the unit out of state to tie in the solar to battery back up the electrical company & county inspectors would have red flagged our electrical. Catch-22

      1. AC,
        I bet the fact that you were ‘not allowed’ to have a battery back up switch on your Utility installed system has to do with the wording of law requiring the utility to have so much ‘renewable energy’ in a given time. I’ll bet that the utility can only take credit for ‘grid-tied’ power to meet their goal. Any ability for your system to be stand alone would not allow them to get credit. The only way you can get stand alone solar is to install it yourself, which is way out of the budget of most people. Sorry you got caught in their nonsense.

  7. I posted this on an article a few weeks ago. But, it’s appropriate for this one too.

    I have several friends and family who are linemen. One of them did “side work” for one of the electric companies installing solar on roofs. He said he would never do it, as it destroys the roof. I’m sure some installers do better jobs than others…

    We have a neighbor who is doing the grid-tie solar panels thingy. One side of their roof is completely covered with solar panels. They had roof damage and leaks after a storm. So all the solar panels had to be removed before they could repair their roof. Looked like a big mess to me and I can’t imagine they are really getting their money back. Beach’n

    1. Beach’n;
      My policy of 45 years in the construction industry, NEVER let an electrician on a roof.
      Like everything ‘some’ may be very good, but the others more than make up for them.
      Mount the Panels on the ground with steal racks poured in concrete, if one can afford it, add a Lightning Protection System on the Racks.

      1. Ain’t it the truth!!!! there are some electricians I would trust too, but why take a chance if you have room on the ground??? Anytime you breach the barrier of a roof to install supports you are asking for trouble. Even if you install the supports as the roof is being built. Besides, if you can put them on the ground they are so much easier( and safer!) to maintain.

        1. My Uncle was a roofer. He said NEVER allow a roof repair person on the roof for an estimate.

          1. Just Sayin’ b=== I have been wondering about this….
            but, if you don’t allow them on, how does one get an estimate (of damages to be fixed/etc)….

          2. Jane Foxe,
            He said if you allowed a roofer on the roof and they were not honest… you would have roof leaks all over the house instead of a problem area…that a screwdriver in a pocket would do enough damage you would require a WHOLE roof instead of just on a garage, or a small patch job..
            One would need to get an estimate for the square footage would want repaired./ then materials can be figured. labor costs are figured with materials cost + for the slope and difficulty of roof…etc. or the coating required to seal an area.
            So a good reason to get someone with good references., ..

    2. Beach’n
      We have to replace the roof on the garage from hail damage, and the solar panels are coming off at that time. Hail damaged the panels, you can see big blotches of missing crystalline.

      They need to be on ground level so when the next owner comes they can protect them without having to do a high wire act just to clean/protect them.

  8. One last thing and I’ll shut the heck up…..

    Next home I’m planning on building will be 100% Off-Grid. Not only Power but Water, Sewer, and Wireless for Phone/Net.

    Once you figure in the cost of running Grid Power to the home, all of the additional Taxes add to the bill, and the Grid Down possibility, I’ll dump my money into the Off Grid System.

    BUT one MUST make sure you buy Land where you’re allow to build without hooking to the Grid, a LOT of States are passing Laws that will not allow Off Grid.

    Again do your homework, and decide the Lifestyle you want.

  9. For smaller solar/wind, like me, I would recommend going with totally off-grid system. You can run a few dedicated solar/wind outlets. I have three. Normally, I try to run my BIG chest freezer and my full size kitchen refrigerator. I have run the proper wire, inside conduit, to these outlets. It is simply a matter of plugging the appliance into the grid or into solar/wind.

    It does away with the need for transfer switches, as these three outlets are not connected to the grid in any way. I am the transfer switch.

    I do have one transfer switch. It’s a manual three position switch, near my meter. I can run on the grid, shut off power completely, or run power from a generator. This allows for using all the normal outlets of the house, from the generator. My solar/wind outlets are not part of that set-up. Those three outlets are only powered from my battery bank(s)/invertor(s).

    There is nothing “automatic” about any of my solar/wind. It requires that I manually plug in appliances to whatever system I choose. My system is very much “hands on.” Though it takes less than a minute to change from one to the other. I don’t even think about it. It has become a routine part of my day.

    Maybe not the best system, but it is safe. Poor people have poor ways!! I would hate to have thousands of dollars in a grid-tied system that wouldn’t provide emergency power.

  10. My system is grid tied – and I was fully aware of that. What bugs me is that since the solar panel shut down is automatic, what cant that automatically shift the power to a battery bank for use? Separate circuitry to prevent feed back to the grid, but very simple to set up. Expensive battery bank? Bought 2 deep cycle 100 AH batteries recently for my RV – $70 each. 10 batteries at 1,000 AH for $700 isn’t too bad.

  11. Wow
    Someone may have already mentioned this, but what a scam…..
    Is it not true, in California, that home owners are now required to install solar?
    The homeowner is required to pay fully for items and installation? And can’t even use it when the grid power is down?
    And I’m sure consumers aren’t being fully credited with non usage, even with said percentages.
    Another way the corporate/state moves ahead, while the consumer pays, for that advancement.
    I wonder how many attorneys it took to come up with that idea?

  12. You need to install an auto transfer switch that will switch to the battery back up and solar system as well. It’s the same switch used with back up generators. Once it detects power from the grid it will switch back to using grid power automatically. The ATS will prevent the back follow of electricity into the grid.

  13. Thanks to all for your responses regarding solar systems. I never had one when I was in Cali. Back then, they were cost prohibitive for anyone purchasing a house. I had a small house slightly less than 1000 square feet. It was small butt it was built of fire resistant material.

    From what I saw, it took a long time for the solar system to pay for itself if it was installed aftermarket. Now I am hearing input that solar panels on rooftops are bad news in general.

    I keep hearing how the price of systems is coming down yet the statements I hear on this site keeps me grounded firmly in reality. It sounds like the industry, the tax breaks, the cost of components are still daunting to consider this for me at present time.

    I just bought myself a Ryobi electric lawnmower and THAT is my one concession to the Green New Deal. Thanks to all for posting your findings and results. Sounds like solar power has a ways to go yet for us home owners.

  14. Calirefugee,
    You are obviously, an intelligent man. Solar/wind is not that complicated. If ya stay with the basics, you can do it all yourself. I utilize all the power I can generate from wind and or solar. It’s way more efficient to use it, than trying to store it. Besides, if ya do it yourself, you will know your system(s) inside out.

    Start out with a cheap harbor freight kit. You can use it to charge your new electric mower. It might take a couple of days to charge your mower, but ya don’t use it everyday anyway. It’s no different from figuring drip rates for IV infusion. Just a suggestion.

    Solar/wind is NOT the total answer, at least for me. The more I learn, the more I realize how much there is to learn. I’ll never catch up!!!

  15. I started out using portable off- the-shelf gas generators (gennys) for my back up power long ago. It was simple as long as you have the room to safely squirrel away the fuel and kept my needs to a minimum, in my case the kitchen appliances, refrigerator, and freezer.

    When I put an addition on my house in ’16 I knew I needed some sort of Solar for a back up for my newly acquired medical equipment. Yep, I getting older, but wiser.

    The genny works well even in a basic system like most building contractors use. But now I needed something to support my medical needs if the power goes at when I’m in bed asleep or sick. Can’t be running around then to set up the genny.

    I went with 6Kw system it runs only in the bedroom and kitchen. The local power made me add in all the switches and stuff. I added eight AGM batteries which gives me plenty of power. It’s overkill, but when you need it, you need it.

    Two last items:

    1) When the power is out use Black out curtains or your neighbors will show up on your doorstep.

    2) Use 12 or 10 Ga Power cords when running from the genny into the house because the smaller stuff will over heat possibly causing a fire.

  16. Enphase IQ8 Series will keep
    The House Side Up while
    The Grid Is Down (for whatever reasons) will be available soon (was Summer 2019, rescheduled for December 2019 or Summer 2020).
    I prefer Enphase IQ8X MicroInverters matched with
    Panasonic N330 Solar Panels.
    High Temperature Fade during Solar Production during Summer is also a consideration.

  17. – I originally looked into the grid-tied system, with the tax relief and “buy-back” provisions. I quit looking when I realized that not only would they not provide power during an outage, there were restrictions in place to keep you from adding the battery bank and inverter that you would need to use the panels during an outage.

    I do have a very small Solar generator that will provide some power in an outage. I can connect it through the “back-up” panels I had added for my generator, which would require me moving 4-5 plugs from one outlet to another. I have not added the larger panels yet, but I can add the one 40-watt I have in my Faraday trash can.

    I have got the two 105-ampere marine battery bank which is currently on a cheapie battery maintainer from HF. I can recharge them from my genset, which I have done several times now.

    I have several 12-volt inverters, including a couple of 150-watt which are sufficient for keeping the kitchen light lit, a couple of 400-watt in the vehicles, an 800-watt and a 1500-watt which one of at least is in the Faraday can and one gets used with the fridge or electric chainsaw when I need it.

    Separate systems is what I would recommend for anyone who is on the grid. I chose a small build-yer-own because i wanted to be able to learn from my system and be able to go larger if I thought I was ready.

    – Papa S.

  18. You all could learn a lot about this subject by studying systems used in motor homes.

  19. I use stand-alone only right now…our power used to go out once or twice a month because we are at the end of the power company’s zone and they hardly ever come out to trim trees out of the right-of-way. Lots of calls, no action So, I said the heck with them and haven’t looked back since. It takes some getting used to, because you’re essentially living on limited electricity supplies, especially in winter when you get a lot of cloudy days, but I really don’t want to go back to the power company with my tail between my legs. No pride, just wasted time. I broke even last year, so I’m free and clear!

    1. That’s always great when you cross that break-even point. Now it’s all ‘gravy’ so to speak. It takes awhile, sometimes a long while. Off-grid solar is not cheap. But if you build a smallish system, it can be done. And getting used to less power availability!

  20. My question is why can’t I put in an ATS similar to those used for backup generators so I can power my house with the solar panels when the grid goes down? Is it not allowed? Seems to me a simple thing to do.

  21. If you use 120 volts there are several grid tied manufacturers with something called an auto transformer. This is a little box that is installed separately from the grid tied inverter.

    When the grid fails, the auto transformer tricks the inverter into thinking that the grid is down, and the grid tied inverter will continue to produce electricity. This will continue until either nighttime occurs or the grid recovers.

    The inverter must be designed to throttle up or down electricity output to match load demand, and it must have the ability to not export electricity during a grid failure.

    Not all inverters can do this, but some do 😊.

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