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Using A Grid Tied Solar System When The Grid Is Down

Resilient Life
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By Samantha Biggers
Thursday, August 19th, 2021

Using A Grid Tied Solar System When The Grid Is Down

Resilient Life
By Samantha Biggers on
Thursday, August 19th, 2021
0

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.

Encharge

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.

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.

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?

– Peak Prosperity –

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