Renewable Energy
All things energy, from solar and wind power to efficiency and off-grid living.


How Long Will It Take to Replace Fossil Fuels With Renewable Sources of Energy?

 

The world is racing to replace fossil fuels with renewable sources and for good reason. People understandably ask, "How long will it take to replace fossil fuels?"

The answer isn't straightforward. However, here's some information that might help.

The Importance of Cost

Some people think cost is the primary reason societies are switching to renewables. According to one study, renewable energy already out-competes oil. While coal is cheaper, technological advances and emission pricing schemes may boost solar, wind power and the like to the top.

Prices for renewable energy are falling, making it competitive with non-renewables. As a result, a transition to sustainable alternatives is taking place across the world. This change, however, doesn't suggest a time-frame for complete fossil fuel replacement.

As more industries realize the potential for renewable energy, others will be more likely to accelerate their transitions. Each eco-friendly choice is a step toward total replacement.

What Experts Have to Say

When we ask experts how long will it take to replace fossil fuels, some say it could happen relatively quickly. Andrew Blakers and Matthew Stocks of Australian National University believe the world is on track to reach 100% renewable energy by 2032. Their research shows solar and wind energy is growing fast enough to surpass coal by the mid-2020s.

Blakers and Stocks claim wind and solar power currently produce about 7% of the world's electricity. It may not seem like a lot, but, over the past five years, solar capacity grew by 28% each year. Wind capacity grew at a rate of 13% per year. These figures, combined with the stagnation of coal power, lead to the 2032 forecast.

On the other side of the spectrum is Shell, a well-known oil and gas mega-corp. In 2017, they produced 3.7 million barrels of oil per day. In Shell's Sky scenario, they imagine a world that complies with the Paris climate agreement. Shell claims they support the idea to keep the Earth's warming below 3.6° Fahrenheit. In this scenario, the world will achieve net-zero emissions by 2070.

Still, we won't replace fossil fuels — they'll only decline. Plus, Sky is merely a scenario — a possibility that's dependent on a number of assumptions. It'll take significant time, effort and government backing to ensure large-scale change becomes a reality.

The Substantial Impacts of Change

Back in 2014, analysts highlighted WTI and Brent crude oil prices on a downward trend. Signs suggest people are looking at new ways to meet energy needs. However, as we transition to renewables, it's essential to consider all possible impacts.

We can't shut down fossil fuel plants overnight. Consider the job losses and those with careers in the industry. Bernie Sanders, a 2020 candidate for President, plans to eliminate fossil fuels by 2050. However, he recognizes the associated losses. Sanders claims protections will be in place for affected workers. He also believes his plan will create 20 million jobs.

Industries that rely on fossil fuels will also feel the effects of a total switch. Businesses must be open to a new status quo. Agreeing to give up fossil fuels and invest in renewables will spur change. According to one study based on existing technology, full decarbonization of the U.S. electric grid would cost $4.5 trillion.

Government leaders must commit to renewables, too. China, the United States and India consume 54% of the world's fossil fuels by weight. Moreover, worldwide usage for fossil fuels equals almost 15 billion metric tons.

Individuals and companies can make changes through purposeful, collective action. However, the nation's leaders must adjust their budgets for an effective transition.

Is a Transition to Totally Renewable Energy Possible?

Some nations. like Denmark and Scotland, get all of their power from wind for brief periods. However, analysts are unsure if some countries can produce 100% renewable energy.

Michael Kelly, a professor at Cambridge University, has concerns about the energy return on investment (EROI) for renewables. EROI looks at the energy a source produces vs. energy invested in making it.

In the case of renewables, we produce wind turbines or solar panels. What's the cost to make one solar panel compared to how much power it can produce? 

Kelly claims EROI for renewables is lower than fossil fuels. As a result, investing in renewables for worldwide electricity could leave less energy for other activities.

Critics, on the other hand, say Kelly's analysis is based on studies from more than five years ago. Since then, solar and wind costs have plummeted.

Can We Fully Replace Fossil Fuels?

How long will it take to replace fossil fuels? The truth is, no one knows. The answer is dependent on many things, from implementation costs to the nation's infrastructure.

For now, focus on establishing eco-friendly habits while continuing to use fossil fuels. Buy a hybrid car or choose a renewable-powered electric provider. Each small step will lead to a significant change.

Photo by Photo by Andreas Gücklhorn on Unsplash

Kayla Matthews has been writing about healthy living for several years and is proud to be a featured writer on a number of inspiring health sites, including Mother Earth News. To learn more about Kayla, you can follow her on Google+, Facebook and Twitter and check out her most recent posts on ProductivityTheory.com. You can read all of her Mother Earth News posts here.


All MOTHER EARTH NEWS community bloggers have agreed to follow our Blogging Guidelines, and they are responsible for the accuracy of their posts. To learn more about the author of this post, click on their byline link at the top of the page.

Going Off-Grid with Solar, Part 2: Two Real-World Examples of Off-Grid Costs

 

This is Part 2 of a two-part series that explores the economics of going completely off-grid with solar. Part 1 focuses on what it actually means to go “off-grid” and how to start thinking about calculating the costs for cutting the cord with your utility. Part 2 discusses two real-world examples of sizing an off-grid solar energy system, along with the feasibility of going through with an off-grid solution.

The notion of living off-the-grid is becoming increasingly popular. Given the rising cost of electricity throughout the country, it’s hard to not at least consider cutting the cord every time a utility bill comes through the mail. But what does it really mean to go “off-grid”? For such a simple concept, the logistics of going off-grid are in fact rather complicated and very costly.

What does it mean to go “off-grid”?

Taking your home off-grid from an electricity perspective means completely removing any connection to the larger electric grid, which powers the large majority of homes, buildings and businesses throughout the country. This means that to go off-grid, you’ll need to meet all of your household needs with electricity produced on-site. 

Importantly, installing solar panels on your roof does not mean that you’ve gone off the grid. Most solar energy systems are not designed to consistently generate enough electricity to be a home’s only power source, which is why the vast majority of solar homeowners maintain a connection with their utility company. 

In these cases, a policy called net metering allows you to put the electricity produced by your solar panels back onto the electric grid when you aren’t using it, and to then pull from the grid when your solar panels aren’t producing, at night or when the weather is less than ideal. At the end of the month or year, you’re billed by your electric utility on the net of production from your solar panels and the electricity you used from the grid, hence the term net-metering. 

In an off-grid solar energy system, you don’t have access to the larger electric grid when you need it, either at night when your solar panels aren’t producing, or in the event of a prolonged period of cloudy weather. Instead, you need to create your own personal “grid”, installing on-site battery storage to store the output from your solar panels for use at a later point in time.

Two examples of off-grid solutions

Instead of looking at averages across the whole U.S. and making several uniform assumptions, as we did in Part 1 of this series, let’s look at what it would take to go off-grid in two real, specific places: Massachusetts and Arizona, two states where solar energy has seen significant growth and support over the last decade.

Example: going off-grid in Massachusetts

In order to go off-grid successfully in Massachusetts, you’ll need to plan for the cold, snowy winter months that typically might have days with only 3 sun hours each. For this example, we’ll assume a residential home using 750 kWh of electricity per winter month, which comes out to 25 kWh of electricity per winter day.

Fewer sun hours in a winter day means you’ll need to install a much larger storage system and solar array to harness enough electricity for your property. What’s more, extended periods of cloudy weather and snow reduce sun hours further. To be safe, let’s say you want to install an off-grid solar energy system with storage that will be able to run your home on solar electricity for one week.

How does the math on an off-grid system in Massachusetts pan out? 7 days of electricity use in the winter adds up to 175 kWh (25 kWh/day x 7 days). Using Tesla Powerwall batteries with 95% depth-of-discharge, that means you’ll need a storage system with a total capacity of about 184 kWh, which comes out to 14 individual Tesla Powerwall batteries. Even if you allow for the small amounts of sunlight that will get through to your solar panels during cloudy and snowy days, you’re still looking at potentially 10 or more batteries.

Once you’ve sized your battery storage setup, you can calculate the panel array size needed to keep it full. Assuming you want to be able to charge 184 kWh worth of battery storage in a week, you’ll need to install an 8.8 kW system (8.8 kW x 3 sun hours gets you 26.3 kWh of electricity per day, and multiplied out over a full week, that adds up to about 184 kWh of solar electricity).

Example: going off-grid in Arizona

In order to go off-grid successfully in Arizona, you’ll need to plan for the hot summer months when you’ll be running your AC at full blast. Unlike winter in Massachusetts, there is plenty of sun to go around, so we’ll assume 7.5 sun hours each day during the summer months in Arizona. We’ll also assume a residential home using 1050 kWh of electricity per month, which comes out to 35 kWh of electricity per summer day.

More sun hours per day means you won’t need to install a much larger solar panel system than usual, but a high electricity load leads to an increased need for storage. And to be safe in the case of cloudy weather, let’s say you want to install an off-grid solar energy system with storage that will be able to run your home on solar electricity for three days.

How does the math on an off-grid system in Arizona pan out? 3 days of electricity use in the summer adds up to 105 kWh (35 kWh/day x 3 days). Using Tesla Powerwall batteries with 95% depth-of-discharge, that means you’ll need a storage system with a total capacity of about 111 kWh, which comes out to a little less than 8 individual Tesla Powerwall batteries.

Once you’ve sized your battery storage setup, you can calculate the panel array size needed to keep it full. Assuming you want to be able to charge 111 kWh worth of battery storage in 3 days, you’ll need to install a 4.9 kW system (4.9 kW x 7.5 sun hours gets you about 37 kWh of electricity per day, and multiplied out over a full week, that adds up to about approximately 111 kWh of solar electricity).

Reduce the cost of going off-grid with energy efficiency

If you’re determined to go off-grid and don’t want to break the bank in doing so, taking appropriate energy efficiency measures around your home to reduce your electricity load is a necessity. In the examples above we assumed standard home setups and standard energy use habits, but by using efficient appliances, properly insulating your home, and shifting your habits to use less energy, you can reduce your electricity load in any type of weather, sometimes dramatically. It’s important to keep in mind that making energy efficient decisions is a way to cut down on the amount of electricity you use, and possibly make going off-grid more affordable.

Bottom line: off-grid is possible, but it might cost more than you think

Going off-grid isn’t cheap. And considering the cost of going solar and staying connected to the grid averages under $18,000 in 2019, it’s hard to justify the extra cost of going off-grid.

For property owners with unusually low electricity loads, an off-grid solar solution might be practical. However, for the vast majority of solar shoppers, going off the grid with solar is a much more involved and expensive process than you might initially think. Costs, physical space constraints, and energy-hungry habits all contribute to make going off the grid a daunting proposition. 

Staying connected to the grid provides the benefit of backup power whenever you need it. Instead of installing 8 extra home batteries to protect against the edge case of an extended period with low solar energy production, you can simply rely on the grid to provide electricity. Of course, that means you’ll need to pay a utility electricity bill. But installing solar panels can reduce your average bill significantly, especially when you consider the added financial advantages of net metering credits.

Going off grid is entirely possible, and it’s even possible to do it while keeping modern conveniences. But it’s rarely as simple or cost effective as installing solar panels and staying connected to the grid.

Jacob Marsh is on the marketing team at EnergySage, the online solar marketplace, focusing on SEO and content. He recently graduated from Tufts University with a degree in Geoscience. When he’s not checking up on the latest Google algorithm update or writing about topics in the solar energy industry, you can find him playing Ultimate Frisbee or rewatching Game of Thrones. Read all of his MOTHER EARTH NEWS posts here.


All MOTHER EARTH NEWS community bloggers have agreed to follow our Blogging Guidelines, and they are responsible for the accuracy of their posts. To learn more about the author of this post, click on their byline link at the top of the page.

Trouble Choosing a Home Geothermal Energy System

 

Geothermal heating and cooling systems have been a topic of conversation for many of my high-performance building projects over the years. I recently came across a project that I thought might be a good fit for geothermal.

This article does not cover the difference in the heating systems. The point of this article is for the reader, to recognize not only the breakdown in information between the leading companies in our area, but also to recognize that we wanted to find the most efficient system for this project. A solid long-term choice would be one that examined what technology currently exists and if that system can be upgraded to be more efficient in the future.

This particular project was a remodel that included an addition. The project sounded like it may be a good fit for a geothermal heating and cooling system, so I inquired about who the builder was. The homeowners replied that they might be looking for a builder and I said that I was interested in being involved. I was very interested in seeing how a geothermal system may work in this project and was excited to be selected as the builder of this project.

Exploring Options for Home Heating

As the project progressed, the homeowners and I decided that it was time to meet with a heating contractor to discuss which heating system would be a best fit for the project. I have always been a fan of reviewing options, so the first heating company representative showed us multiple systems, which included: upgrading the existing propane-fired forced-air furnace with air conditioning, a mini-split systems, an open-loop geothermal system and a closed-loop geothermal system.

I have learned throughout the years that there is not a magic one-size-fits-all solution to heating and cooling in a home. My hope here was that geothermal was going to be the best value versus performance for this project. The homeowners had heard that geothermal was the most efficient heating and cooling system available, and we were going to rely on the heating and cooling company to show us the performance data to see if that was correct or not.

The house was built in the early 1990s, and I was impressed with the tightness of the house. The exterior of the house had 1-inch foam sheathing with 2-by-6 walls and fiberglass insulation. The attic insulation was blown-in insulation, which, in my opinion, could use another foot of depth for better performance.

The addition that we built onto the existing house has insulated concrete form (ICF) basement walls with 2-by-6 main floor walls. We would spray foam in the walls and to the bottom of the roof deck. Another thing to note is that we stayed in the house as we were working on it, so I could witness how well the house heats and cools with the current forced-air system.

We met with our heating contractor and were presented with a number of options. It’s hard not to focus on the price tag of each option when looking at a heating and cooling system. There was a range of price from about $14,000 to $36,000, with the highest price tag for a closed-loop geo-thermal system. As a group, we gathered our composure and started to go through each system to see cost versus performance.

We asked specific questions about each system and the heating and cooling contractor did a good job of explaining everything except for why some systems were so expensive. After the meeting, we still were not close to making a decision on a heating and cooling system. We decided to contact another heating and cooling company who had been in the geothermal business since the 1980s. We set up a meeting with this company and they sent their sales manager to meet with us. We were once again very interested in learning all that we could about the cost versus performance of geothermal systems.

Trouble Getting Clear Information on Home Geothermal

My first impression of the sales manager wasn’t that great. I knew about a few “smoking guns” with geothermal systems, especially in the area of this project. I sat back, listened to his sales pitch, and waited to throw my curve ball. 

When the moment was right, I asked him a question that derailed hi and his sales pitch, “What about iron bacteria in the groundwater shutting down an open-loop geothermal system? His response sunk his ship, “We have installed thousands of open-loop systems and never had one shut down because of iron bacteria.”

“Not one?” I replied with a tiny hint of question in my voice.

“Well,” he said, “I will have to check with the owner to be for sure.” Here was a top geothermal company with decades of experience telling us that. The red flags went up and we thanked him for his time and asked him to send us his price — which came back very close to the first company’s, except he’d offered a larger geothermal system in his bid. We wondered why the two different companies had conflicting information about the size of the geothermal unit. One of the responses was, “that is what the computer says that this house needs.” Which size unit was the correct size?

Two companies into this quest and neither of the companies said the same thing about open- and closed-loop geothermal systems. The information was completely different between the two companies, including that one company said that an open-loop system was more efficient than a closed-loop system and visa versa with the other company. We all looked at each other and agreed that we needed to meet with a few more companies to try to find a common thread so that we could understand which heating and cooling system was a best fit for this project.

Over the next week or so, we met with three other heating and cooling companies. To our surprise, each of those companies gave information that contradicted what the other companies said. One company quoted a price in the $50,000 range for a closed-loop geothermal system while the others were in the mid-$30,000 range. All companies mentioned the un-capped 30 percent federal tax credit, which put the net cost of a closed-loop system back into the mid-$20,000 range. Each company’s computers told us a different unit size was appropriate.

Evaluating Electric Heating Assist Systems for Home Geothermal

One of the questions that I asked each contractor had to do with the electric heating assist, which is part of each type of geothermal system. These electric heating elements are what are used for heat when the temperature gets too cold for the geothermal system to operate the way it is intended to work. In a closed-loop system, the electric heating assist system starts operating when the earth around the buried closed-loop tubing drops to near freezing, which in Michigan, can occur as early as the beginning of January.

In an open-loop geothermal system, air temperature dictates when the electric assist starts heating the house. Some units say that 28 degree Fahrenheit is when the electric heating assist starts operating. Experts would probably add that the heating load is what determines when the electric assist turns on. We have a house that was built a decade ago and that house has an open-loop geothermal System and $680 per month electric bills because the electric assist was the primary heating source when it gets below 28 degrees. 

Each of the contractors said that the electric assist will not run that much if the system is sized properly. We were very confused at this point, because each of the five contractors had systems that were sized differently. When I brought this point up to the sales people, they simply said that the computer decides the size of the system. One company told us that the electric assist will only come on once or twice a month. I asked him to write us a guarantee stating that and he back tracked and said that he can only go by what his computer says and that he couldn’t guarantee that.

We had our favorites with regards to who presented us with the information. It was a great experience seeing how salespeople approached this topic. Geothermal is such a hot button for homeowners that these sales people basically just need to sell themselves and show numbers to support their claims to get the sale. But selecting a heating and cooling system based on how much someone likes their salesperson is a recipe for unhappiness.

Comparing Cost of Home Geothermal to Other Options

I will present you with some of the figures that we were given. One of the figures that stuck in our minds was that the difference in operating costs per year between the geothermal closed-loop system and a high-efficiency, propane-fired forced-air furnace with a heat pump, which ran for $800, or $66.66 per month. There is about a $20,000 difference in price depending on options, and I did not figure in the tax credit into this equation.

What I recognized immediately was that the closed-loop system was not extremely more efficient as it was presented to us. We can debate this in the comments section (in fact, I encourage that). Technically speaking, the geothermal would be less to operate than the forced-air with the payback on the geothermal being about 20 years — about how long one of the salespeople said that the geothermal unit would last before needing to buy another unit.

As a sustainable builder for many years, I have fostered open-mindedness to anything as long as the science and my experience supports a technology. I will be honest and say that I went into these meetings with the heating contractors with an open mind and a blank piece of paper for note taking. I was giving them the opportunity to change my mind and I did get my hopes up a few times as I heard the information being presented with such confidence. Confidence coming through in a sales pitch is a double-edged sword in my experience, and in this instance, it created many red flags.

Which System Did We Choose?

You may be wondering how this turned out. Well, after all of the meetings and reviewing of information, we decided to go with the first contractor. We decided that installing new, high-efficiency, propane-fired forced-air furnace with a heat pump (acting as air conditioner during the warm months and heating during the cold months) and using the existing ductwork as much as possible was the best fit for this project.

Four of the five geothermal contractors told us that they would have to remove the existing ductwork and install new ductwork. We also added extra zones to the heating and cooling system along with upgraded air filtering and purification components. The difference in price between the systems, versus a closed-loop geothermal system, was about $16,000. As a team, we decided that a portion of the $16,000 difference would be applied towards a solar hot water system and solar panels to produce and store electricity.

Photos by Adam D. Bearup

Adam D. Bearup is a designer, green builder and farmer, who learned about biodynamic and regenerative farming for a project he built in Northern Michigan, The Earth Shelter Project MichiganAdam has degrees in marketing and management and a Masters of Science in Green Building. Read all of his MOTHER EARTH NEWS posts here.


All MOTHER EARTH NEWS community bloggers have agreed to follow our Blogging Guidelines, and they are responsible for the accuracy of their posts. To learn more about the author of this post, click on their byline link at the top of the page.

Going Off-Grid with Solar, Part 1: What Does it Mean and How Much Will it Cost?

 

This is Part 1 of a two-part series that explores the economics of going completely off-grid with solar. Part 1 focuses on what it actually means to go “off-grid” and how to start thinking about calculating the costs for cutting the cord with your utility. Part 2 discusses two real-world examples of sizing an off-grid solar energy system, along with the feasibility of going through with an off-grid solution.

The notion of living off-the-grid is becoming increasingly popular. Given the rising cost of electricity throughout the country, it’s hard to not at least consider cutting the cord every time a utility bill comes through the mail. But what does it really mean to go “off-grid”? For such a simple concept, the logistics of going off-grid are in fact rather complicated and very costly.

What Does It Mean To Go “Off-grid”?

Taking your home off-grid from an electricity perspective means completely removing any connection to the larger electric grid, which powers the large majority of homes, buildings and businesses throughout the country. This means that to go off-grid, you’ll need to meet all of your household needs with electricity produced on-site.

Importantly, installing solar panels on your roof does not mean that you’ve gone off the grid. Most solar energy systems are not designed to consistently generate enough electricity to be a home’s only power source, which is why the vast majority of solar homeowners maintain a connection with their utility company.

In these cases, a policy called net metering allows you to put the electricity produced by your solar panels back onto the electric grid when you aren’t using it, and to then pull from the grid when your solar panels aren’t producing, at night or when the weather is less than ideal. At the end of the month or year, you’re billed by your electric utility on the net of production from your solar panels and the electricity you used from the grid, hence the term net-metering.

In an off-grid solar energy system, you don’t have access to the larger electric grid when you need it, either at night when your solar panels aren’t producing, or in the event of a prolonged period of cloudy weather. Instead, you need to create your own personal “grid”, installing on-site battery storage to store the output from your solar panels for use at a later point in time.

Calculate the Cost of an Off-grid System in 4 Steps

Going off-grid with solar requires more than just installing solar panels and disconnecting from your electric utility. There are four key steps to determine if going off-grid is feasible for your home, as well as how much it will cost:

  1. Calculate how much electricity you use;
  2. Determine how many solar batteries you will need;
  3. Design a solar panel system to fit your needs;
  4. And add up the costs of the combined solar plus storage system.

How Much Electricity Do You Use?

The first step in going off-grid is understanding how much electricity you use, alternatively known as your consumption or your electricity load. To figure out how many solar panels and solar batteries you need to go off-grid, you need to know how much electricity your home uses each day.

There are two primary ways to calculate your home’s daily electricity needs. The first, and easiest, is to find the monthly consumption number on your electricity bill (expressed in kilowatt-hours, or kWh). To get daily electric consumption, divide your monthly usage by the number of days in the month. Since usage can vary from month to month, it’s a good idea to perform this calculation for multiple months.

The second method for calculating your daily electricity load is a “bottom-up” approach: multiply the wattage of each appliance in your home by the number of hours you use it every day. Though you may not be able to find the specific wattage for all of your appliances, most large household electronics - like TVs or refrigerators - come with a yellow Energy Guide sticker that estimates yearly energy use. Divide that number by 365 to get an estimated average daily electricity load for these appliances.

One of the best tools available for estimating energy use is the Department of Energy’s calculator. Based on that calculator, here are some estimates for the electric load of common appliances:

Appliance

Estimated annual load (kWh)

Estimated daily load (kWh)

Refrigerator

600

1.6

Air conditioning unit

215

0.6

Central air conditioning

1,000

2.7

Space heater

600

1.6

 

The approach listed above is a great way to review your historical energy usage, though may not be as useful to forecast future energy consumption. The second approach, on the other hand, is better at forecasting what you may use in the future. Both of these approaches are estimates, though; if you’re planning to install solar and storage to go off-grid, it may be worth purchasing a home energy monitor to get a more precise estimate of your electricity usageYour electricity consumption directly impacts how large of a solar plus storage system you’ll need to install. By first conducting an energy efficiency audit, or by adjusting your consumption habits (for instance, by air drying clothes and dishes instead of using electric heat), you can decrease the cost of going off-grid substantially.

How Many Batteries Will You Need?

In order to go off grid, you need a way to store the electricity produced by your solar energy system at times when you’re not using it. Importantly, not every solar battery can operate independently of the grid, even if you’re feeding it solar energy. To go off-grid, you specifically need a battery that can “island”, or form its own grid, so that the panels will recharge the battery every day without a grid connection.

To determine the number of these batteries you need to power your house for a single day, you need to know both your daily electricity consumption and the amount of electricity stored in a standard solar battery.

The amount of electricity stored in a battery is called the “Usable Energy”, expressed in kWh. This is the amount of electricity that you can get out of a battery, after accounting for electrical losses and any energy needed to power the battery itself.

With these two data points in hand, calculating the number of batteries you’ll need is straightforward. For instance, the average American household uses about 30 kWh per day. Given the conversion losses associated with storing electricity, you’ll need enough batteries to store slightly more than what you use per day, likely closer to 32 kWh, depending upon the efficiency of the battery you select.

Two of the most common solar batteries are the Tesla Powerwall 2 and the LG Chem RESU 10H, which store 13.5 kWh and 9.3 kWh of usable energy, respectively. So in this example, the average American homeowner would need 3 Powerwalls or 4 RESU 10H batteries to meet a single day’s electricity need.

It’s important to remember that this is just the number of batteries you’ll need to power your house for a single day. In reality, you’ll want to have enough backup storage capacity to power your house for many days, or even an entire week, in order to ensure you still have electricity if you have a period of inclement weather or need to use more than your average daily usage in a single day.

How Many Solar Panels Will You Need?

Next, you’ll want to design the solar energy system that will supply electricity to your property and storage setup to be large enough to fill your battery every day.

The electricity you a solar panel system produces is directly a result of the amount of sunlight your panels receive. The average home in the U.S. receives an average of 5 sun hours per day over the course of the year, which represents not the amount of time panels are in the sun but rather measures the number of hours during which sunlight intensity is 1,000 W/square meter. The amount of electricity your panels produce is also related to the angle they’re placed at and whether they receive direct sunlight all day or spend time in the shade.

To determine how many solar panels you need to fill your batteries every day, divide the amount of electricity needed (in this case, 32 kWh) by the number of expected sun hours (5 in this example):

32 kWh / 5 hours = 6.4 kW

Thus, we need a solar panel array of about 6.4 kilowatts to fill up a battery bank with a capacity of 32 kWh each day.

The number of solar panels you’ll need for a 6.4 kW system depends on the power output (in watts) of the solar panels you use, which generally range in wattage from 250W to 400W:

Solar panel wattage (W)

Number of solar panels for a 6.4 kW system

250

26

300

21

350

18

400

16

Adding up the costs

The average cost of solar in the U.S. is $2.98 per Watt, meaning our 6.4 kW system comes to $19,072 prior to incentives. A single installed Tesla Powerwall battery costs between $9,800 and $15,800, so installing three Powerwalls would likely cost somewhere between $29,400 and $47,400 before incentives. Add that together and you’re looking at a total installed cost between $48,215 and $66,615, before any rebates, tax credits, or other incentives are applied.

However, remember that these are just the costs for a system capable of powering an average American home for a single, average day. In reality, not every day requires the same amount of electricity, nor is every day perfectly sunny. While the average daily usage in American households is 30 kWh, hot summer days with AC on full blast could use as much as 80 kWh.

Once you start considering both seasonal and day-to-day weather variations, the prospect of going off-grid becomes vastly more complicated. What happens if it rains for a week straight, or if you live in a region with snowy winters? Just an hour of cloudy weather during the day could reduce the production of your solar array by up to 20 percent, meaning that if you only size your solar plus storage system to perfectly meet your average daily consumption, there may be many times throughout the year when your system doesn’t produce enough electricity to power your home. As a result, in nearly every case, to go off-grid requires more than a single day’s worth of backup electricity.

The only way to safely go “off the grid” is to make sure you’re ready for the most extreme situations possible, because being left without power and without the electrical grid to pull from can be a potentially dangerous situation to find yourself in. In the Northeast, an off-grid solar installation needs to account for fluctuating electricity loads during the seasons, as well as the possibility of greatly reduced production in winter months due to snow cover or cloudy days. In the Southwest, high AC use in the summer may require a larger-than-usual array and storage system to keep your home comfortable during the hot months.

Why Go Off-grid?

There are homes that function very well off-grid with smaller and less expensive solar and storage systems. But these homes are designed specifically for this purpose, often because they are located in remote areas that don’t have access to an electricity grid. Some of these houses are built to Passive House standards and require very little energy for heating or cooling. Others use wood burning for space heating and limit the extent of electrical systems in the house. Homeowners in these situations may pay a premium for these features, or manage their lifestyle with an expectation of time periods throughout the year without electricity.

In the majority of instances, however, the desire to go off-grid may be less about cutting the cord with your utility and more driven by improving resiliency. By installing one or two solar batteries with islanding capabilities, you can ensure that your house remains powered even in the event of a severe weather event or outage on the rest of the grid. For most solar shoppers, this is a cost-effective way to improve the resiliency of your home without breaking the bank to go off-grid entirely.

Jacob is on the marketing team at EnergySage, the online solar marketplace, focusing on SEO and content. He recently graduated from Tufts University with a degree in Geoscience. When he’s not checking up on the latest Google algorithm update or writing about topics in the solar energy industry, you can find him playing Ultimate Frisbee or rewatching Game of Thrones.


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Lights when Living off Grid

 

My name Aur means light or to enlighten in Hebrew and since I grew up without electricity but love to read late into the night I have always looked for ways to lighten up my life. 

Most of our lights were the yellow light of a fire, candle, kerosene lamp or flashlight.Growing up we tended to go to bed at dark and wake up at light although in the winter due to the very short days we ended up spending a decent amount of money on candles or kerosene for our lamps. 

As I got older (9 or 10) I got a job so I was able to start buying batteries for a flashlight or a headlamp  to read. I remember once getting so enthralled with a book as I read under the covers (it was a cold winter night) all night that when my dad got up at daylight at 5 or 5:30 I was still reading. He gave me a little lecture saying I would ruin my eyes. 

I was even able to once buy a hand cranked flashlight which was good for walking the dark paths but not good for reading as I had to continuously squeeze crank it for it to work. 

I really think I got into solar due to wanting light and not having an affordable readily available good source. In an upcoming post I will write about the evolution of my tiny off grid system. I worked all summer doing low paying (poorest county in Tennessee) menial jobs to save up to buy my first solar module to primarily power lights which were 12 volt halogen tail light bulbs run off of an old truck battery. I couldn’t run them very much as they used around 50 watts of power so I bought some 12 volt DC 13 watt CFLs (compact fluorescent lamps) so I could run one bulb for around 4 hours to use the same energy as the halogen used in one hour. 

The first LED ( light emitting diode) bulb  I bought was $157 wholesale but it made it so I had plenty of power as this bulb only used 3 watts.  I went from using 50 watts to 3 watts an hour for running a lightbulb. 

We say for every $1 (dollar) spent on energy efficiency you can save $3-$8 on your solar system. Of course now that LEDs are much cheaper there are lots of solar and/or battery operated LED lights for great prices. 

May your life be well lit and may it be solar powered! 

Aur Beck has lived completely off-grid for over 35 years. He has traveled with his family through 24 states and 14,000 recorded miles by horse-drawn wagon. Aur is a presenter at The Climate Reality Project, a fellow addict at Oil Addicts Anonymous International  and a talk show co-host at WDBX Community Radio for Southern Illinois 91.1 FM. Find him on the Living Off Grid, Really!?!?Facebook page, and read all of Aur's MOTHER EARTH NEWS posts here.


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Into the Wood: A Day in the Life of an Off-Grid Entrepreneur

flooded 

Today's Off the Grid job was only 2.7 miles from pavement versus last Friday's off the grid job was over 6 miles from pavement and I had to ford a stream. Also last Friday I had to go the long way because Snake road was closed. Some days my life is an adventure. #GetEnergized #GoSolar

Truly a Couple of Off-Grid Customers

The GPS tells me that it'll take 14 minutes to go 5 miles and I almost make it only to find THE Road was flooded as well as washed out so I had to backtrack about 30 minutes. I made it through a majority of the road even though it was washed out in places due to a big rainstorm yesterday. But I made it through most of it. I knew that snake road was closed for the snake migration so I went to take another road but I didn't know that it was completely flooded. In the end I had to take the longest route around but made it.

One customer we put their system in 2 years ago and I was doing a check up on it.

10 year upgrade

The other customer put their system in at least 10 years ago and is now tripling their solar so they can put in air conditioning and a pool. He did a self install but he was smart enough to have me come to test and make sure the system was wired up, and hooked up correctly which it wasn’t.

ZENN

It turned out to kind of be lucky that I got lost because as I was getting turned around a guy pulled up with a truck pulling a trailer and on the trailer was as an ZENN electric car of which only about 500 of them were ever made. He told me that it cost $66,000 to make each one and they were listing them for under $17,000. This all electric car was made from scratch to be all electric with an all aluminum frame and ABS plastic body. He said it's 72 volts ( 6- 12 volt ) batteries and that it only goes about 25 miles on a charge. So basically a hopped up golf cart. All I know is it was completely unexpected to be deep in the woods and run into a guy who was just driving all the way from Chicago (about 6 hours)  where he had got this car off of Craigslist.

Before I bumped into him I was kind of cranky that I had gotten not really lost but had to completely backtrack almost 30 minutes of traveling.

I did see a wild turkey and some really nice nature as I drove through Trail of Tears State Park. I usually follow the GPS as it tells me the shortest way but it never really tells me the shortest time. Although we probably wouldn't have known that the road was washed out and the creeks were still high.

I look forward everyday to the interactions I have on my Living Off Grid, Really!?!? Facebook page and hope you will join the discussion there.

Stay energized, aur

Aur Beck has lived completely off-grid for over 35 years. He has traveled with his family through 24 states and 14,000 recorded miles by horse-drawn wagon. Aur is a presenter at The Climate Reality Project, a fellow addict at Oil Addicts Anonymous International and a talk show co-host at WDBX Community Radio for Southern Illinois 91.1 FM. Find him on the Living Off Grid, Really!?!? Facebook page, and read all of Aur's MOTHER EARTH NEWS posts here.


All MOTHER EARTH NEWS community bloggers have agreed to follow our Blogging Guidelines, and they are responsible for the accuracy of their posts. To learn more about the author of this post, click on their byline link at the top of the page.

Should You Purchase a Solar-Ready Battery for Your Home? 5 Energy Storage Considerations for Homeowners

home-rooftop-solar-system

Energy storage technology has existed for quite some time, but the use of solar batteries in residential energy systems is a relatively new development. Although home energy storage prices have fallen significantly in recent years, solar batteries still have a decently hefty price tag and do not make economic sense for every homeowner. However, a solar-plus-storage system can be beneficial in some situations.

Ask yourself the following questions to determine whether or not solar battery storage is the right fit for you and your home.

Are you required to pay time-of-use electricity rates?

If your utility company charges time-of-use rates, this means that the amount you pay for electricity will vary depending on the time of day. During hours when electricity demand is high, typically in the evening and at night, you’ll pay more for power than you would when electricity demand is low, typically during the late morning and early afternoon.

If you are subject to time-of-use billing, a solar battery can be a beneficial investment for you because during the daytime, your solar system will be producing enough energy to both power your home and charge up your battery. Then at nighttime, you’ll be able to use the energy stored in the battery to power your home rather than having to pull from the grid at the higher time-of-use rate.

Does your utility require demand charges?

Some utilities charge customers an additional fee that’s dependent upon how much electricity they use. The fee could be determined by the amount of power used when total electricity demand is high, or it may encompass all electricity used during a month.

If you’re required to pay demand charges to your utility, installing home energy storage can be beneficial by helping you to avoid a high demand fee by pulling from the grid less often and utilizing energy stored in your solar battery instead.

Do you live in a state with net metering?

In states where true net metering exists, customers will receive a credit equal to the amount the utility charges for traditional electricity for each kilowatt-hour of energy their solar panels produce and send back to the grid.

If you have access to true net metering, a solar battery may not be worth it for you from a financial standpoint because you’ll be able to freely give and take energy from the grid at no additional cost.

Are you susceptible to frequent power outages?

For safety reasons, all standard grid-tied solar systems have an automatic shut-off switch that will turn off the system during a power outage. This means that those who have a standard solar energy system without battery backup will still lose power when the grid goes down. However, when a battery is added to the setup, the home can still run off of the energy stored up in the event of a blackout.

If you experience regular power outages and would like to continue to have power when the grid is down, or if you’re interested in the peace of mind that comes along with energy backup, a solar battery may be worth the cost.

Do you want solar storage to take you off the grid?

Many homeowners are interested in the idea of going completely off the grid and having the ability to operate totally independent of their electric utility, and some view solar batteries as the means to make it happen. However, on their own, most solar batteries on the market today do not have the capacity to store the energy necessary to keep a home running throughout the entire year.

If going 100 percent off the grid is your goal, solar batteries likely aren’t the best solution unless you have ample space available and are prepared to invest tens of thousands dollars in a large multi-battery storage setup.

Sarah Hancock educates consumers about the workings of the solar industry to help people make decisions that benefit both their own interests and the environment. Connect with her on the Best Company Solar Blog and on Twitter. Read all of Sarah’s MOTHER EARTH NEWS posts here.
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