Using A Grid Tied Solar System When The Grid Is Down

Many people have taken advantage of programs that make putting solar panels on their homes and tying to the grid very affordable. Unfortunately, these types of solar systems provide no backup power if the actual power grid is down. The main advantage to homeowners is that their power bill is significantly reduced or even eliminated. The power is fed back into the grid, but no battery backup system at home can be utilized if the main power grid fails.

During a long emergency, there will be many solar panels with a lot of power potential that will suddenly be unable to help produce needed energy unless someone has the equipment and knowledge to adapt the system.

It is important that those that have grid-tied systems make sure that they invest some time and money into coming up with a reasonable solution for utilizing their system.

Why are grid-tied systems designed to shut down when the grid is down?

The answer to this is pretty simple. Power companies don't want a lot of people feeding uncontrolled renewable energy into the grid if it is truly down because it can be dangerous if they are trying to pinpoint the problems and take care of repairing them.

Even during a short-term outage, the power company needs to know that there is no dangerous live current flowing when they send our repair teams.

Most solar systems that utility companies install were installed to reduce or eliminate their electric bill while also producing extra electricity for the utility company to send wherever it is needed. They were never intended to be backup systems during an outage or long emergency. Those who install their own systems intend to have an independent power system that can function no matter what shape the main electrical grid is in.

Battery Storage

You can add some battery storage to your grid-tie system and use that energy when there are short-term power disruptions. Of course, this requires monitoring your usage. Even if you have quite a few batteries to store power in, you will likely need to be more conservative with your energy usage.

Lead-acid batteries cost less, but they have to be maintained. This means checking water levels regularly. You can purchase lead-acid batteries at any automotive store and a lot of hardware and big-box retailers. You can buy them one at a time as you can afford them, and there are often coupons at auto stores that you can take advantage of to save some cash.

Lithium-Ion batteries are great because they are essentially maintenance-free and have a longer lifespan. The cost of lithium batteries has gone down a lot over the years, but they are still more expensive than lead-acid on average.

Adding Battery Back-Up To Existing Grid-Tie System

Utility companies work with contractors that install solar on residential houses. Someone my husband and I know signed up to have a grid-tie system; they were offered a battery backup option but found that the quoted price was just outside their budget at the time. The good news is that battery backup can be added to an existing system. I have to say that you may even find it more affordable since by adding it later, you have the option of shopping around a bit and maybe getting a better deal on equipment and labor.

Here are a few videos that explain some battery backup options for grid-tied systems.



Tesla Powerwall

If you have the budget, you may consider a Tesla Powerwall or even several of them if you want a lot of backup power. The cost for each installed Powerwall goes down a lot after the first. Getting an installer out there and some of the base equipment makes the first one a lot more expensive than additional ones installed at the same time.

The advantage of the Powerwall is that it has the highest storage capacity of any actual solar battery on the market. The problem is that it can take a really long time to get one due to demand, and they are usually not installed on older systems. There are reports that they are only available for new solar installations.


This lithium ion-based battery storage system just came onto the market. Like the Tesla Powerwall, it is a battery system that you definitely have to get a professional installer for. Encharge is part of a larger Enphase system that places a microinverter under each grid-tied solar panel on your roof.

Utilizing A Power Center

One way you can easily add some backup power to your grid-tie system is to purchase a larger solar power center or "generator." When you do have power, you can make sure this unit is fully charged and ready to use if the power goes out. You could even purchase a few solar panels to keep it topped off if the outage lasts too long. Think of this as your satellite backup system. Keep in mind this is not a perfect solution. You will need to reduce your energy consumption, and you won't be able to use standard outlets in your home, for example.

The advantage is that you can buy one of these units and immediately have a backup. In addition, you don’t have to know how to wire anything.

Power center prices vary based on the size and brand you choose. Larger power centers are mounted on hand trucks that allow you to move them around with ease. Even though most are made with lightweight lithium-ion batteries, the weight can add up when you are buying a whole-house backup system.

[caption id=“attachment_646185” align=“alignnone” width=“562”]<img class=“size-full wp-image-646185” src=“” alt=“”" width=“562” height=“568” /> The Goal Zero Yeti 6000x offers a lot of backup battery power that can be easily charged off the 2000 watts that a Sunnyboy Inverter can provide via your rooftop solar panels.[/caption]

For more info on solar power centers and more, check out my Peak Prosperity article “Small Scale Solar Setups”.

Sunnyboy Inverters

This is a grid-tied inverter that has a feature that allows for some backup power. When the grid goes down, the Sunnyboy disconnects from the grid and performs a series of safety checks. After the safety checks are completed, you have a short 45-second wait until the Sunnyboy provides power to a single dedicated outlet that supplies up to 2000 watts of power from the panels on your roof. While that is better than nothing, it still means that the average home is going to have to limit what they use until the grid goes back up.

The Sunny Boy is a very affordable inverter. At the time of publication, some modes were under $1,300. If I used a Sunny Boy, I would add in a solar power center for battery backup. Consider that with a 2000 watt outlet, you could keep a large Goal Zero or Kobalt Power Center charged up for use when the sun was not shining. You could even chain several together, and it would still cost less than a single Tesla Powerwall or similar. On top of that, a solar power center is portable, so you have some flexibility.

Sungold Power

We ran across this brand of inverter when researching what we would need to add to our solar power system to run our well pump. The ability to get water from our well has been the big hole in our preparedness for quite some time. Fortunately, a good inverter, some extra batteries, and some panels are all we need to add to have a complete backup system for most things in our home and the added ability to run our well pump. Of course, solar hot water will be added too.

Charge Controllers

Midnite Solar 150 MPPT Charge Controller

Midnite Solar has been around a long time. This is the charge controller we use at our house. This style comes in a variety of sizes to fit your system needs. It can be used with solar, wind, or hydropower systems. You can monitor the charge controller from your computer or Smart Phone, so you don’t always have to walk to the location of the charge controller to view info. Data from your system is logged for up to 380 days. In addition, Midnite Solar charge controllers have built-in safety features such as ground fault protection and short-circuiting protection.

Just so you know, the prices listed on the company website are far higher than what you can find their products for at online solar retailers. Therefore, I advise shopping around for the best price if you intend on purchasing a Midnite Solar product.

Outback Solar

Although I have no personal experience with Outback Solar products, I do know that they are a company that is well known in the solar industry, and they have been around for a long time. Like Midnite Solar, they carry various charge controllers to fit the size of almost any system out there.

Generic Cheap Charge Controllers

There are a ton of cheap charge controllers on Amazon that come from basically unknown or generic manufacturers. We have used a few for small satellite or portable solar setups. For example, if we want power at an internet relay point, we use a $25 charge controller. For my main house charge controller, I am glad we went with a well-known brand. If you have used larger charge controllers from less expensive or no-name brands and they have performed well, please share in the comments below. There are just so many controllers out there that it is nice to hear some feedback from actual users of specific models.

MPPT vs. non-MPPT Charge Controllers

MPPT charge controllers are better for long-term needs and larger solar power systems. This is because MPPT charge controllers allow for a more efficient power draw from your system. With larger systems, these gains can be substantial. However, if you have just a small portable solar array you keep on hand in case inclimate weather results in a power outage for a day or two, then the cost of an MPPT charge controller may not be worth it to you. Small power centers designed for this and are all in one unit, such as Jackery or Goal Zero products, have built-in charge controllers for maximum efficiency.

Here is a video that explains in-depth the difference between MPPT vs. PWN (non-MMPT) Charge Controllers.


DIY Options For Long Term Emergencies

Let's consider the worst-case scenario. The grid is down, and no one really knows if and when it will come back up or how well it will function when it does.

Thousands of homes have signed up for solar programs through their power company and have a lot of panels on their roofs that are still capable of producing a lot of power, but that power is not accessible.

Knowing how to get those systems functional, even if it was just during the day when sunlight is hitting the panels, would be an invaluable skill to have.

Below you will find rough guidelines for what you need to accomplish.

  1. Disconnect the grid tie charge controller.
  1. Connect your own charge controller.
  1. Make sure the voltage and amperage are right for the charge controller you are using when you take the system off the grid.
For example, if your charge controller cannot handle the total voltage of your panels, you would have to go on your roof and disconnect enough panels to bring your total voltage within the limits of your charge controller.

Useful Skills and Supplies

If you are at a point in your preparedness plans where you have a little extra money to budget, it may not be a bad idea to put back an extra inverter and charge controller. Having a spare would allow you to help other people harness some power and these items are higher value barter items.

I could see during a very long emergency communities attempting to create their own independent power supplies to take care of essential needs.

Key Facts to Remember

Charge controllers vary a lot in cost, but you need to remember that you don’t have to be able to harness all of the power from all the panels on the roof of a home with a grid-tied system. So a smaller charge controller that costs less will at least allow you to have some usable power.

Also, keep in mind that you do not need a charge controller if you only want to harness energy during daylight hours, but you do need a good inverter wired in. This will at least allow you to take care of some tasks during daylight hours. You could run your well pump and fill up your water containers, for example.

Professional Installation Vs. DIY

Like any home improvement or specialized work, it can be cheaper to do the labor yourself, even if it takes you a little longer. At the same time, you need to be realistic about your skillset. Maybe you have a friend that has a lot of solar experience that you can work out a deal with? Other than that, hiring someone to do the actual work of installing backup solar may be necessary. Some components can be pretty darn heavy too, so if you are not up for the physical part of it, hiring some help for the heavy lifting is a wise decision.

Solar power systems can be confusing and complicated, even if you have some experience with the basics. When you start messing with grid-tied systems that other people installed, there is a lot of catch-up work to be done in terms of understanding the ins and outs of your system. My husband did the work on our solar system and built it from the ground up. We built our whole house together so we both can tell you what type of lumber, insulation, or other materials were used.

If you do decide to work on your grid-tied system yourself or ever find yourself in a long emergency that leaves you little choice, you will be glad that you took the time right now to review your system and learn as much as you can. Right now, you can research and ask questions, up to and including getting info from the contractors or utility companies you worked with. I am not sure how much info they leave homeowners with after a grid-tied solar system is installed. If they left you with any booklets or guides, review them now.

Have you ever been without power due to having a grid tied system? Have you added a backup battery system? Is there anything you would like to tell someone that is having a grid tied system installed soon or making decision on what type of equipment to invest in?

This is a companion discussion topic for the original entry at

I chose nickel iron Edison cells because they are indestructible until some idiot puts acid in them.
I had a lot of trouble in the beginning until I ditched the controller. The batteries need much higher voltage to charge properly. (16.5V or greater). They are perfectly matched to the characteristics of photocells.
Just include over-current protection, and you’re good to go. ( fuses or over-current trip switches)
12V electronic equipment can be provided with 12V regulated power. Cheap from electronics stores.
Get a Victron inverter for mains voltage. They will protect themselves from over-voltage.
A simple voltmeter in your house tells you what is going on.
If you have too much solar power, (the batteries are too small), either dump the power by pumping water or somesuch and/or turn off banks of panels with a simple switch.
The advantage of owning your own powerstation are obvious. The advantage of using a Utility company is that you outsource the technical hassle.
Edison Cells can sometimes be bought cheap from people who gave up in dispair.
Catch rainwater to fill up the cells. Do not use rainwater that has been in contact with metal. Clean, very clean, water.
Don’t worry, Gladys, you too can learn to use your system.

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Turn off or remove your main breaker.
Connect a small 240v generator or 240v battery/inverter to your stove or dryer socket,
With careful timing/switching, your grid tie system will probably think it still has grid power and keep on working.
I had a grid tie system I switched on and off when main breaker was off and generator was powering the house. I could hear the generator load go up and down when I switched the grid tie system in and out.
So with sunlight, and no modifications, you can likely use your grid tie solar power that way, using the inverter in the grid tie system.

We have a grid tied system with battery backup. This year we should hit our target of net zero energy on the electrical system. We have no other fuel source except wood, which we use two and a half to three cords, depending on the severity of the winter. We bought logs this year, which will save a lot of money. Can get two and half times as much wood for the same price.
We have sealed lead acid batteries, same as you use on a house boat. They are sealed and require no maintenance. We have had then for 10 years now and they are still performing well. Had an outage that lasted around 6 days this year and we had all the essentials. With enough sun we can run indefinitely, water (we are on a well), hot water (we also have solar hot water), refrigeration, and enough lights in every room. Wood for heat.
In the next couple of years will need to replace batteries, will probably go lithium ion, but they are expensive. May get two units, so we don’t have to watch are usage so carefully, and it would give us the option of go off grid if things get really crazy. Just debating if it is worth spending the money on the “world goes crazy” insurance. We have a large garden, so we lots of fresh fruit and vegetables in the summer, but being food self sufficient is a whole different level. Need to integrate animals, build a lot of hoop houses. Still not sure we could get all that to work on 1.5 acres. Will always need a larger community around us to some degree.


Batteries that fire up engines are not suitable for power backup.
Also keep in mind that you need a converter that is large enough to provide peek power (I don’t know the correct English word for that).
I have a converter of 2000 Watts continuous and 4000 Watts peek. I am not able to start a compressor, to reach 8bar. Eventhough it has a 1300 Watts engine. Also our waterpump of 1200 Watts will not start. The peek power it needs is to large.
What I mean to say; don’t just buy stuff and keep it in the box, with the intention to use it when things go bad. You will encounter troubles you will not be able to overcome.
Build a small gardenhouse and install your materials. It is always easier to upscale later.
Another thing: you can get way more from your panels in the winter when you do aan intelligent mixture of serial and parralel connections.

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The usual starting current for a squirrel cage motor is 6X the rated full load current draw. (On the nameplate)
I’ve used soft starters to lower the starting current.

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Good to hear from you again, treebeard. Always appreciate your voice on this site.

Hi Arthur,
What is a soft-starter? Is it some device between the machine and the power outlet?

A soft starter lowers the surge amps when a motor starts. Mostly used on Air Conditioners. Saw a demo where the start up amps went from 70 to 39. If you are off grid it is essential. I just built an off grid house for a man who could only afford one SolArk 12kw inverter. It limits off at 37.5 amps, so it was imperative to size the house load below that. The 3 ton ac system never draws more than 26 amps and has a built in soft start. It is inverter type that changes AC to DC. The design works but doesn’t leave much room for other loads. With propane appliances we are getting by. We are wired to accommodate a second inverter when he can afford it.
Our battery bank is 22.5 kw……using 3 kilo vault 7.5 hab lithium batteries. We have stayed away from Tesla because of the fire hazard. There are lots of options in the lithium battery space. I’m looking at Discover and Simpliphi on 2 upcoming installs.…
and be careful buying a big battery.
what about Marvin Motsenbocker? He wrote a book Chris Martenson endorsed……’take back the power’. Honeymoonfarm is still ongrid I guess.
I’m building a offgrid house, but no one is interested in 12 volt it seems. Even RV’s are 120/240 volts.

I picked up two banks of emergency power batteries from a coal fired power plant, both were 128 volts dc, one bank was 145 ampere hours per cell, the other bank was 165 ampere hours per cell. These were edison cells, and were cycled about 20 times during the time they were at the plant. I paid about 100 bucks over the scrap value and got both battery banks for 385 dollars. These battery banks show up several times per year on the GSA auction website. A call to the power plant will confirm the condition and past use history of the batteries. In 1990, the total cost of two battery banks of this type was $36,000. All of the cells were good and were used to store hydroelectric power from a small dam. These are the same type of battery used to start diesel locomotives, with a short circuit current of 1500 amperes. They had a dual bus bar arrangement and came 4 cells per wood tray. The electrolyte had been dumped out prior to purchase and water added to make the cells “safe” to handle.

I need a simple, inexpensive gas-fired backup power source to do the following: Power my freezer, power my oil-fired furnace, maybe run a microwave. Not necessarily all at the same time.
Moving before I install a permanent solution, but need something now.
Can you suggest good, easy to use models that don’t require installation, just a heavy shop extension cord?
Thanks in advance.

I have a system that was designed from the beginning to have battery backup, it has an inverter and a subpanel of loads that are powered by the inverter/batteries. I have had this for 22 years. I have 48V solar panels and it is a 48V DC system to the batteries/DC side of the inverter, 120V AC out of the inverter ( max 60 amps). It is grid intertie on the AC side out of the inverter. WHen grid power is down, the inverter just does not feed to the grid, it senses it. Back when I did this, people that wanted more backup power ran 2 of these inverters in parallel, so then had up to 120amps available at once. I changed all well pumps/booster pump to 120V, grundfoss soft start well pump, so I have run well pump, refrigerator, lights off of the inverter and batteries. Right now I am transitioning to not running any water pumps off the batteries, I have a new well pump that will run off of AC or DC power, a grundfoss SQ Flex, and a few panels I bought used that I havent connected yet, so I will run the pump off of direct DC soon. I now have water tanks uphill, so I can get water with no power to the second pump (the pressure pump) but it is low pressure. The plan is to leave the pressure pump connected to grid power ( although I can move that wire back to the battery backup sub panel whenever I want) and just have gravity feed lower pressure water when there are power outages or SHTF situations.
I do not have a very large amount of panels or of batteries, but it has always been sufficient ( unless I do something silly like ply loud music off of the stereo too much when the grid is down). The “label” watts of my original solar array was 2400W, which my installer considered 2000W after all conversion losses, reality of sun angle, etc… I later added a second small string of 630W “label” watts, so maybe 500W useable power. SO total of 3000W “label” watts on the roof at this point, and I will put a few other panels direct to the well pump, I may purposefully limit this to not overpump the well, but max of 3 panels in series, with one bypassed in the summer. This takes a significant load off the main house system.
Battery bank has varied over the years, right now it is pretty small amount of KWh, about 7 kWh but can be discharged all the way with no damage. Salt water batteries.
My house is all electric with no propane or gas. I heat with wood, about 1 1/2 cords a year, if I ever get around to doing more house caulking, ever get curtains up, etc… I think I can get that down further. When grid power is out, the biggest thing is that the backup electric hot water and electric range cannot be used. In winter power outages, this is not an issue as the wood stove can cook and heat a pot of water while it is heating the house. In summer outages, I am usually using the Sun Oven for the major amount of cooking anyways. FOr earlier heating or quicker heating of food and rink I have done the following : Off of the inverter ( so from battery backup power) I have used all the small kitchen appliances, electric kettle, toaster, breadmaker. Last year I finally tried out a single burner induction burner, which worked great ! WHen the sun is out and recharging the batteries everyday in teh summer, this is not an issue. I use the sun oven extensively all the time anyways. And, I have used my portable rocket stove, burning sticks, to do for example a quick fry up of homemade Naan bread to go with the sun oven cooked main dish. I have used this rocket stove to boil water for scalding chickens, so I know I can heat up a large pot of water on it if I wanted to, but mostly I dont care it is so hot in the summer

Barbara……I think the best bet might be a 7 or 8 kw propane generator. Tractor supply sells a dual fuel….either gasoline or propane. I would recommend a propane connection. One tank of propane can go a lot longer than your small gas tank.

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You/we might comment on the newer generation of gas/propane/deisel generators that are “inverter” + generator that are 2x to 3x more efficient in varying load situations. :slight_smile:
IE I would not today buy an AC generator, rather an inverting/inverter generator. Ask at the showroom.

For my DIY system, I have 4 grid tie inverters, a multi-fuel generator, and a transfer switch on my service panel. One time when I switched over to the generator, I forgot to disconnect my grid-tie inverters and everything seemed to work fine, although I worried about damaging the generator (it’s an inverter type). Another time, I threw the transfer switch but did not start the generator and was surprised to find my computers in the house were still running. Seems the grid tie inverter can’t tell the difference between grid power and power coming from another grid-tie inverter in the system. Now I have TP-Link HS-103 wifi power switchs on each of my grid-tie inverters so I can switch them into or out of the system from my smartphone (Kasa), so I think I have the bases covered.

Great article with lots of info.
We have a pretty big off grid solar system…yes Lithium batteries are expensive but worth the cost IMO.
Some comments were asking about soft start motors.We replaced our well pump with a soft start pump and it works really well.Those types of pumps slow down the initial draw of current so you don’t get as big a spike when the pump starts up…near as I can tell the starting draw is about 50% compared to a traditional pump.

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He is out searching for the truth.
BTW in grid tie systems with grid down you can use a small power source like a tiny generator or inverter to fool the big system into sensing it has grid power.

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Hi CrLaan and Random Mike
Nice to hear from you and your interests. I am focusing on simple circuits to connect solar panels to 3 phases motors and regular AC motors. The circuits allow one to add solar energy when available (displace utility power directly), for cost savings when any amount of sun shines, while allowing off grid use when enough panels are available. I intend to add three more chapters to my book, one to do this for lighting (big opportunities for someone to sell/install large systems for warehouses/grocery stores), one for AC motors and one to review the problem of how to improve circuit quality/lifetime and repair of your own equipment over the years, instead of throwing things out (following Charles Hugh Smith`s example of replacing/repairing things to avoid the “landfill economy.”)
Visiting Shenzhen was a trip. Imagine entering a large and long building, packed with booths 12 feet wide in narrow corridors. Now imagine 7 more floors of the building stuffed with small sellers in booths for things from switches, transistors, chips, crystals etc. and then 5 or 6 more large buildings like that on the same block. Everyone in all these booths are selling parts, and subassemblies for cell phones, computers etc. I bought many parts and met people from factories or closely working with factories.
By the way, this Friday evening 6 PM Eastern Standard Time Idan and I are having a video conference dedicated to mutual help for people who are using our DIY Grid system. If you bought my book “Take Back The Power!” at, then you should already have received an invitation. I hope to work on a second edition of my book, which would provide details for building absolutely all equipment (including high voltage battery charges and AC motor inverters) needed to harvest and use solar energy for all appliances. Maybe I will get that done by Summer.
I look forward to meeting you again on the East Coast this coming late Spring.


All the above are great systems and really what you need for a true off grid system. But if you know nothing about solar and dont know how to start and the above is a foreign language… or dont have a lot of cash to invest … a great way to learn and get a minor backup system cheap… is a harbor freight setup… No before I get attacked by the experts here on how its crap and a toy and not a real system…it depends on your definition… it works, its cheap, its simple and it portable and I great beginners class all in one,. if you grab a coupon out of a magazine you can get 3 little panels, an invertor, 3 led lights in a 15 minute plug and play system for a whopping $150… add a $40 Ac convertor for harbor freight for 120 plug ins and a deep cycle battery "craigslist a good one for $50… and you have back up power to run lights, computer, phones even TV for a couple hours a day… the 100W setup will recharge 1 battery in 1 to 2 days… I have 2 kits- 4 batteries and can even run power tools for up to 4 hours at my shop. Now 100W system with a car battery is a TOY in terms of a 13,000 W true setup with a lithium battery bank yes but the cost is ~1% and can keep you in light and communication. Its also a great way to learn the setup and how it work… Yes after the toy 25W set up. which worked at my shop for years . I eventually upgraded to 250W panels and professional invertors and solar batteries as I could run a sawzall… but my learning curve was much quicker. I was able to know what pieces I needed, pick them up second hand for 20% the cost… keep in mind and this setup is also portable… you can throw it your trunk if you have to camp/bugout into the woods.