Hi. I’m Amy at the altE Store. Probably
the most frequently asked question we get here is, “How much solar does it take to
power my 2,000 sqft home?” My answer is always the same. “I don’t know. How much
power do you use?” I’m not trying to be flip, I honestly don’t know. The power usage
for different homes are going to be so wildly different, there is no way of knowing how
much power someone uses based on their square footage. Is the house located in the north
with bad insulation and electric baseboard heaters? Or is it a house with a tight building
envelope and gas heat? Is it located in the south with the highest loads being air conditioning
run 24/7, or is it in a mild environment with a couple of fans occasionally? Are you heating
your water with an electric water heater, or an oil furnace? Do you have family members
who find it challenging to turn off a light when they leave the room (you know who you
are)? Are you lighting with incandescent or LED light bulbs? The best way to determine how many solar panels
you need is to look at your electric bill and see how many kWh a month you buy.
can then go to our grid-tied calculator to see how much solar would be needed to offset
a percentage of your bill. Here’s an example of my electric bill. It
shows 13 months of usage, so I can compare the latest month with the previous year. It is amazing what you can learn by studying
your electric bill. By comparing the usage in different months, I can see my biggest
use is in the summer, with the air conditioner running all day because of the home office.
You can see that my usage dropped significantly from August 2013 to August 2014, as well as
from July to August in 2014.
<highlighting bar as I mention them> We went away every
weekend in August 2014, and turned the AC off while we were gone, saving us $85 from
the previous year. But unfortunately, we went away for a week that July and forgot to turn
down the AC, so it stayed on high, cooling an empty house all week. You can see that’s
the highest usage in 13 months, and was completely preventable. That mistake cost me about $160.
In November we switched the mini-split from AC mode to heating mode to delay turning on
our oil heat, bringing our electric usage back up. It cost an extra $135 to heat the
house with electricity that month, but saved us at least that much on our oil bill. By
December it was too cold for the heat pump to work, so we turned it off and turned on
the oil, dropping our electric use.
So even in the same house, with the same people, behavior
changes the electrical use dramatically, thus changing the answer to the original question,
“how much solar do I need to power my house?” I recommend you look at your monthly usage
and analyze it, what was your big energy user each month, and could a change in behavior
reduce it? Once you understand your electric use, then you can start to figure out how
much solar you need. Our average use is about 1,500kWh a month.
I used that number in our on-grid calculator and decided to see what it would take to make
all of our power with solar, netting us down to 0. That would require around a 13,000 Watt
solar system for my area, around 50 solar panels. This chart shows my last 30 months
of electric use, and the estimated output of a 13kW solar system on my house for that
With Net Metering, I can use any power I generate
during the day, and sell the extra to the grid. Then at night, when my system isn’t
generating any power, I can buy it back from the grid, spinning the meter back and forth.
Any additional power I need gets bought from the grid, same as usual. Likewise, with months
that I make more power than I use, like in the spring, I can bank the credits to use
them in the summer and winter when I don’t make as much as I use. Today’s average
costs would be around $26,000 to buy the equipment to install it yourself, or about $52,000 to
have one professionally installed (depending on equipment and location).
of federal and local incentives could cut the cost by ⅓ to ½ in the US, depending
on your location. This system could pay for itself in about 8 years for me. After that,
and for the next couple of decades that my system keeps humming along, the $3000 a year
I was paying to the electric company stays in my pocket. Plus with rate increases, that
savings is bound to grow over the years.
But a nice thing about net metering, and staying
connected to the grid, is I don’t have to make all of my power like if I was off-grid.
I can instead decide to make half my power, or less, and buy the rest from the grid, resulting
in a lower monthly electric bill. You can see from this graph that charts both
my monthly use and my projected monthly solar generation with a 6.5kW solar system, that
for a couple of months I actually would make all of the power that I use, but on average,
I would make half of the power I needed, cutting my power bill in half. That still gives me
a significant monthly savings.
Solar isn’t the silver bullet for reducing
my electric bills. We’re also working on further reducing our power use. We recently
replaced all of the shop lights in the basement with LED tubes. This brought that power use
from 2500W down to about 250W! And the light quality is actually better now than with the
old lights. We’ve replaced all of our incandescent light bulbs throughout the house with LED
as well. We’re also trying to get smarter with the programming of the air conditioning,
cutting down on our biggest power user. So you can see why the most common question
we get asked here is also the most complicated and personal question to answer. Grab your
electric bill, go to our calculator, and find the answers for your home. I hope this was helpful. If so, give us a
like and a share. And check out more of our videos here. Also subscribe to our altestore
channel so we can notify you when more videos come out. Also go to our website at altestore.com,
where we’ve been making renewable do-able since 1999.