Off-grid or on-grid?

Fri Sep 23 2022

As we're building our dream home in Vermont, there's one big question we have to answer: should we connect to power or go off-grid?

Off-grid or on-grid?

The vast majority of new homes built today are connected to the power grid for electricity. In fact, in many states it is legally required to connect to the grid.

But in Vermont that's not the case, and despite the often harsh weather conditions, plenty of people here choose to live off-grid. While our property does have utility poles down by the road, that's more than 1,000ft from where we're building the house.

Building a Driveway

An old logging trail won't cut it for long - we need a solid 1,000ft driveway from the road to our house site.

Building a Driveway

Which begs the question - are we better off going off-grid?

Our energy demands

To answer this question, the first thing we need to understand is what our energy demands might be.

According to the U.S. Energy Information Administration's 2015 Residential Energy Consumption Survey, an average single-family detached home in the Northeast consumes about 10.6MWh of electricity per year, or about 29kWh per day.

Just to put some monetary numbers to that, the current residential electrical rate as of writing this article (September 2022) with our utility company is $0.17650/kWh, equating to an annual electricity spend of around $1,870.

However, this is only half the story, since wintertime heating requires huge amount of energy in this northern climate. Many people here in Vermont opt for wood, wood pellets, oil or gas for their heating.

By way of anecdotal evidence, a cord of seasoned firewood (a standard measure of firewood equivalent to 128 cubic feet) is currently selling around here for roughly $400, and a typical home might burn 3-7 cords during the winter - or about $1,200-$2,800.

Likewise, we've heard from neighbors with oil-burning heating systems who've said that monthly bills in the region of $700-1,000 during the depths of winter are to be expected.

An all-electric Passive House

Given the fact that our property is over 40 acres of predominantly hardwood forest, you might expect us to be cutting, splitting, stacking, seasoning and burning our own firewood.

Cutting Firewood

We turned the trees cleared from our driveway construction into enough firewood for a LOT of campfires using a chainsaw, homemade sawbuck and hydraulic log splitter.

Cutting Firewood

And we will, but not to heat our home.

We're taking a very different direction. We're building an all-electric home - no combustion in the house. All space heating, water heating and cooking will be electric-only - no gas, oil, wood or coal burned inside the home.

In fact, our firewood is solely for outdoor use - camp fires, maybe a pizza oven, making maple syrup and so on.

The Maple Syrup Experiment

We tried making maple syrup from scratch for the first time by tapping our own trees and boiling the sap on a campfire - it was a delicious success!

The Maple Syrup Experiment

I'm not going to go into all the details here as to exactly why we have chosen to build an all-electric home, other than to say that one of our goals is to create an incredibly comfortable, healthy and sustainable home. In doing so we hope to achieve at least partial certification for arguably the world's most rigorous green building standard - the Living Building Challenge.

In order to make this viable, a key approach is insulation. Well designed, modeled and executed construction techniques that pay attention to rigorous air sealing, avoid thermal breaks and employ ample insulation not only make for a comfortable and healthy home, but also one with substantially lower heating loads.

We are therefore striving to also build a Passive House - a standard for high-efficiency homes that began in Europe and is beginning to take off in the US. The Passive House standard defines not just prescriptive requirements for the design and build, but measurements of real-life performance are required for certification.

Building to these exacting standards will inevitably increase the up-front build costs, but should go a long way to substantially decrease the ongoing energy costs of the home, making an all-electric home a viable option even in a climate such as Vermont.

Electric vehicles

I'm a firm believer that electric vehicles (EVs) are going to change everything. While there are arguments about the environmental impacts of building electric vehicles, particularly their batteries, I believe that as they become more prevalent, innovation will drive down the cost - both financial and environmental.

Furthermore, fossil fuels are not a sustainable long term solution. They are a finite and rapidly depleting source of energy, not to mention the demonstrable irreparable harm they are wreaking on the environment both during extraction and use.

Aside from the many other impacts that EVs will have on modern society, the pertinent one for this discussion is the inevitable increase in demand for electricity - every mile driven in an EV rather than an ICE (Internal Combustion Energy) vehicle is one mile's less of gas from a pump and one more mile's worth of electricity required, even if that electricity is still, in the short term, generated from fossil-fuel guzzling power stations.

The simple fact is that owning an EV will substantially increase our electrical demands - both in aggregate energy consumed and peak rate of consumption.

While we don't have an EV now (nothing on the market can currently offer a replacement for the capabilities we regularly leverage of our F-150), we very much see one or more EVs in our future.

Why we love our Ford F-150

It's hard to find a vehicle that's a comfortable daily driver, performs well off-road and is able to safely (and legally) tow our trailer. Our Ford F-150 manages it all and we love it!

Why we love our Ford F-150

To give a rough sense for what I mean, let me show you some numbers.

In the past 6 months that we've been in Vermont, we've driven roughly 6,000 miles, so about 1,000 miles per month - and remember, the RV hasn't moved off our property that whole time, so this is fairly typical of what our "steady state" consumption might be.

The closest currently available (kind of) EV to our truck is the Ford F-150 Lightning which, based on real-world reviews, seems to run at around 2 miles/kWh in generous conditions (likely lower in winter, for example). At our current mileage of 1,000 miles per month or 33 miles per day, assuming we always charge at home (which we likely would), that would add about 500kWh per month or 16kWh per day.

Battle Born Cold Charging Study: Analysis

Can you use lithium batteries in cold temperatures? That's what Battle Born sought to find out in their study, and here's our analysis!

Battle Born Cold Charging Study: Analysis

Remember, an average single-family detached home in the Northeast was using about 29kWh per day in 2015, so this is more than a 50% increase in total electrical consumption.

Last, there's the question of peak power draw - in other words, how much instantaneous current are you trying to consume? Search the EV forums and you'll find many EV owners unhappy with conventional "slow" charging, particularly for the larger EVs like the F-150 Lightning. Plugging an F-150 Lightning in to a conventional 120V AC receptacle will charge the vehicle at a rate of about 2 miles per hour - in other words, we'd have to charge it for over 16 hours to recoup each day's usage.

Consequently, most people opt for faster chargers, assuming their service panel can support it.

Ford's Charge Station Pro operates at a (for residential applications) massive 80A at 240V, meaning a peak draw of 19.2kW. Bear in mind that 100A service (i.e. the size of the main breaker and hence the total current available for the entire home during times of peak consumption) is not uncommon for many homes, and it puts things into perspective.

The bottom line is that if we want to have an EV and charge it at home, and we do, it massively increases our electricity demands.

Connecting to the power grid

I talked earlier about the consumption costs of sourcing electricity from the grid, but they aren't the only costs. Many utility companies, including ours, charge a monthly connection fee - in our case, about $15/month.

But by far the biggest cost for us to connect to the grid is the upfront cost - pulling service from the road up to the house site, around 1,000ft up our driveway.

Without getting into the specific details, our quote from the utility company was around $16,000 to provide electrical service for our property. By any stretch of the imagination, that's a BIG number.

Which led us to the question in the first place: should we go off-grid?

But there are a lot of advantages to connecting to the grid:

  1. It provides (fairly) reliable power all year around - while storms can knock out power lines, in general the grid works year round, regardless of weather. In the event of a large storm, dedicated teams of engineers work to get the issues fixed without me having to get involved (e.g. clearing snow from panels)
  2. It can handle big peaks - even a modest 150A service can provide almost 30kW of sustained load, something that would require a significant investment to achieve off-grid
  3. It's a giant battery - with net metering you can provide power to the grid when you have excess (e.g. a sunny day in summer) and pull from the grid when you are at a deficit (e.g. a cold, snowy day in winter)

Solar power

If you've been following our journey for any amount of time, you'll know that we love solar. We spent over 2 years, traveling full-time in our RV around the US with no generator - all our power came from our solar panels.

Our Perfect Off-Grid RV Solar System

Find out how we upgraded our RV with Lithium batteries, solar panels, an inverter and more so we could camp off-grid in comfort!

Our Perfect Off-Grid RV Solar System

It's a fully DIY system and in addition to being a huge advocate for solar, I've helped install several systems and given talks on the subject at various RVer events.

YouTube Video Player
RV electrical basics & RV solar explained (RV Electrical Upgrades talk at Xscapers Annual Bash 2020)

You don't have to sell me on the benefits of solar.

2021 Online RTR: Basic Solar

Solar brings the promise of free, silent, and off-grid energy - but is it really that simple? Join me as I take a look at the basics of RV solar, including what makes up a solar system, the pros and cons of solar, and how to get started.

2021 Online RTR: Basic Solar

Even here in Vermont, a well-oriented solar panel array will generate roughly 1,000kWh per 1kW of panels over the course of a year. To put another way, an average home's annual electrical demands of 10.6MWh (excluding EVs) could be generated with 10,600W of solar panels.

Doing it yourself, a price of around $2/Watt should be attainable, so for an investment of a little over $20,000, you'd have enough solar to produce all the energy you need for a year. And once you factor in the federal tax credits, it could be cheaper to install that solar system than to connect to the grid - and then free power for life!

Easy, right?

Well, not so fast. You see, for solar panels to produce power you need...sun. Right now, as I write this article in late morning in mid-September, our 800W of ground-deployed tilted solar panels connect to the RV are currently producing just 16W - or 2% of their rated maximum. That's because it's a grey, cloudy and rainy day here in Vermont - not exactly unusual!

Victron CCGX Display
I'm not joking - that's just 16W of solar power being generated from 800W of panels. Solar panels need sunlight to work!

And it should be obvious that solar panels don't produce power overnight or when, for instance, they're covered with snow!

So to make solar power viable, you need a way to store the energy when it's available for use when it's needed. We do this in the RV with our Battle Born Batteries, but a house requires something a little bigger.

RV Electrical Upgrade: Part 2 – Battle Born Lithium Batteries & Victron Inverter

In Part 2 of our series on upgrading the electrical system in our RV, we're going to be jumping straight in with the biggest components - the Battle Born Lithium batteries and a new Victron MultiPlus inverter / charger . We'll also be laying the groundwork needed for installing the remainder of the system later on in the series too.

RV Electrical Upgrade: Part 2 – Battle Born Lithium Batteries & Victron Inverter

Energy storage

Batteries are everywhere these days - our phones, our laptops, our watches and so on. A myriad of devices rely on an assortment of battery sizes and chemistries to provide temporary (or sometimes long term) power without being plugged in.

But what if you want batteries big enough to run your entire house?

It's absolutely doable. The Tesla Powerwall batteries are perhaps the most well-known example, but there are many other options out there too. Fundamentally you need three things:

  1. Some big storage batteries
  2. A way to charge those batteries
  3. An inverter to turn the battery's DC voltage into the 120/240V AC you house needs

Using the Tesla Powerwall 2 as an example, while costs vary substantially, an estimate of somewhere in the region of $10,000 per 13.5kWh battery with a built-in 5kW inverter is a reasonable ball park for an installed cost.

To put it another way, you'd require roughly two Tesla Powerwall batteries per day of consumption for an average house, or about $20,000 per day of energy storage. Not cheap.

Backup generator

If you want backup power in the event of a grid outage or rainy day, batteries aren't your only option. Many homes in vulnerable areas make use of whole-house generators, some of which run on propane and automatically kick in when the power goes out. And solar-reliant off-gridders nearly always have a generator of some size to get them through days when their demands exceed the available solar power.

Why? Because honestly, they're an incredibly cost effective option.

Our small, $300 portable gas generator can charge our nearly-5kWh of batteries from 0-100% on well under $5 worth of gas. So an average household could power their home with a generator for less than $30 per day in an emergency situation. It takes a lot of days of power outage to make batteries look effective!

Given that the average US resident in 2020 experienced about 8 hours of blackouts, a generator can often be a very good option.

But there are some downsides. Generators are noisy. They need maintenance. They burn fossil fuels. They take time (several minutes usually) to switch on and start providing power. Large, whole-house generators take up a lot of space - not just for the generator, but also the propane tank.

Grid-tied solar with battery backup

OK, that's a lot of theory and hypotheticals. I've also glossed over a lot of detail and completely omitted some concepts such as V2H (Vehicle to Home) and V2G (Vehicle to Grid) charging. We did a lot of research into this before coming up with our decision.

It's hard to guesstimate what our electrical demands will be, but for the sake of argument we can assume that 30-50kWh per day on average would be a realistic target for an all-electric home with one or more EVs.

Going off-grid with that level of consumption given the climate here in Vermont would lead to two major issues:

  1. We'd need a lot of solar panels to provide sufficient power to heat and run our home during the cold, snowy winters with short days
  2. We'd need a lot of energy storage or a backup generator to get us through days of very low solar production - e.g. snow storms

Aside from the massive cost of either approach, a solar system large enough to carry us through winter would massively over produce in summer when generation is higher and demand is lower.

On balance of all these considerations, the solution we chose is as follows:

  1. Connect to the power grid - while expensive, this provides the power we need, when we need it (most of the time)
  2. Install grid-tie solar - this will help to offset a lot of the energy demands of our house over time through net metering
  3. Add batteries for short-term backup - batteries can be rapidly brought online to keep critical infrastructure in the house running, e.g. lights, fridge / freezer, network connectivity, etc
  4. Provide additional connectivity for a backup generator - as a last resort for longer outages, we can connect one or more generators to recharge the batteries and provide power

One of the main reasons we chose this approach is because it is iterative. We don't need to jump in and do everything at once but can start simple and add as we go - always with the end goal in sight.

Initially we'll connect up to the grid. If there is a power outage, it's not a problem - we've been living off-grid in our RV for 6 months, have batteries, solar panels and two portable generators if we need them.

Once we have the utility building constructed we can add solar, offsetting our electrical demands, and hence cost. We can then begin adding batteries, scaling the system as our build progresses, taking advantage of the (hopefully) decreasing costs of batteries over time.

Summary

The decision to connect to the grid or stay off-grid is not one we took lightly. While I've condensed the highlights for this blog post, in reality we spent weeks poring over numbers, hypothetical system designs, quotes from local companies and more.

The reality is that the electrical grid is unparalleled by off-grid solutions available today. While the grid isn't perfect, it's ability to reliably deliver high peak power year round at a relatively low cost is very costly to match off-grid.

This approach may not have been the cheapest, but it does satisfy all our requirements and gives us the maximum possible capability for our dream home.

Given our decision, the next step is to plan out our electrical service.

Photo by Matthew Henry on Unsplash.

Previous postWell Install: Part 4 - Water Testing