What does it take to get the average family home right off the grid

What does it take to get the average family home right off the grid

According to the US Energy Information Administration, the average family home uses about 30kWh of electricity every 24 hours. What would it take in terms of solar panels and Powerwalls to get such a home right off the grid?

Earl and Nagin ... | 4 maj 2015

Its going to take a lot of solar panels and a lot of energy storage.
The amount depends on a lot of things:
- Location (is it cloudy often where you are? How much sun do you get in winter? etc)
- Roof orientation
- What are you operating? (gas heat? gas water heater? pool? EV?)
- Are you ok with having a diesel or gas backup generator for long, cloudy periods?
It takes quite a bit of analysis for your specific case to answer this question.

jstack6 | 4 maj 2015

If you charge at Tesla Super Chargers it keeps your home use less since they are free and away from your home.
If you don't need much heat or Air conditioning like California it would not take a lot of solar PV or batteries.

For most it would take 4 Tesla 7K battery units, 8 kW of Solar PV , an Inverter to match and all the installation cost and permits. It is very possible to do but could cost $40-50k

Incentives are starting in California and other places for Solar with Storage so that could drop the price in half.

NOTE the big growth in Solar was because GRID Tied didn't require any batteries. You could make 1/3 rd or 1/2 or 2x times what you use and even miss a few weeks or months. It was easy and simple. As equipment cost dropped it became too low cost and easy so utilities are losing revenue.

Utilities don't have storage so they blame solar customers. Utilities have been dumping Mega watts Off Peak for years but just past the cost to home owners and business.

rlwrw | 4 maj 2015

Remember that if you live in an area where you can also use wind, hydro and/or any other type of power generation, that too can be combined into your system.

7thGate | 4 maj 2015

It is bad, but not nearly as bad as the moody article suggests. You only need a 2 month battery to smooth summer-winter cyclical trends if your solar PV average generation is above your yearly average use but below each individual month average use. If you were going off grid, you clearly want enough solar PV to meet average summer demand, then just dump excess power generated in the winter, because it is cheaper to buy twice as many solar panels if it lets you buy 5% as many batteries. Then you still need a few days of battery power, which will be very expensive, but not nearly as bad as the article makes out.

Red Sage ca us | 9 maj 2015

That Forbes article merely convinced me that Moody's findings were [FOLDING BOLSHEVIK]. By claiming the minimum amount of battery storage necessary to go off grid with solar/wind/hydro was two months of energy, they are comparing to diesel and propane systems -- which do not miraculously refill themselves every day.

Most people who actually own solar systems say they would be satisfied with having one week of energy storage, 'just in case'. So claiming a minimum of two months' storage is a 'bare minimum' needed to 'cut the cord' from utilities is eight times the actual, required expense -- in effect, overkill.

Last time I looked, the majority of people in the world did not live within the Artic Circle. I certainly find the prospect of living in the Great White North rather depressing -- that's why I live in California: because you can't shovel sunshine.

The reality is that those who live in the sun belt can get by with only 1-3 days of battery storage capacity. And they can very comfortably support a solar system with 7-10 days of battery storage capacity. Thus, that supposed 535¢ per kWh expense may be reduced to 1/8th (only 66.875¢ per kWh), or 1/60th (8.196~¢ per kWh) instead for batteries. And unlike utilities, it is a one-time expense, rather than an eternal, revolving, monthly payment that always costs more, year after year.

Brian H | 10 maj 2015

Markets will differ greatly in cost/kWh. The sunbelt may be a special case.

DonS | 13 maj 2015

If you have power lines in your back yard, it has never (at least not with current costs) made sense to go completely off-grid.

Not many people will want the inconvenience of adjusting their usage to stay under the peak capacity of their system. The alternative is to buy a way oversize system that is rarely used to full capacity. Something as simple as a Christmas holiday with a house full of people and ovens and cook-tops running is enough to break the "average."

In computers, there is a field called queuing theory. It pretty much says that average loading is irrelevant because requirements are lumpy and tend to bunch up. You have to plan based on the peaks even though there is low utilization between the peaks. The concept is applicable to computers, home energy usage, and checkout lines at the grocery store.

Red Sage ca us | 13 maj 2015

There is a distinct difference between the phrases 'have never', 'will never', and 'can never'.