Solar Power Shingles: Bright Idea or Bad Investment?
"Unisolar shingles are unique and have been honored with the prestigious
Popular Science Grand Award, Best of What’s New, and Discover Magazine’s
Technological Innovation Award for best innovation."
It's hard to argue with Popular Science, but exceptional technology doesn't
always guarantee an exceptional return on your investment.
To illustrate this point, let's take a look at an actual solar shingled roof installed
on a 1200 sq. ft. home in Ann Arbor, Michigan.
Here's a breakdown of the components and the cost for each:
84 Uni-Solar SHR-17 solar shingles: $8685. One shingle is 84" long
comprised of (12) 7" tabs that resemble individual shingles. The total
output of this system is 1428 watts, or 1.4 kw (84 shingles x 17 watts).
Outback FX2548 Inverter, 49-volt DC to 120-volt AC, 2500 watt $1640
" FXA Adapter Kit: $109.65
" PS2MP mounting plate: $103.20
" HUB-4 Communications Manager: $165.75
" RTS Remote Temperature Sensor: $24.65
" MX60 Maximum Power Point Tracking Charge Controller: $499
" PS2AC-50D AC disconnect box: $305
" PS2DC-100 DC disconnect box: $260
" Mate Remote Monitor and Control: $235
Shipping for above items: $149.17
Total cost for solar specific hardware: $12176.42
In addition to the solar specific hardware, the system uses 8 - 530 amp, 6 volt
batteries at $232 each for an additional $1856 plus shipping. By the way, these
batteries are shipped "wet" and weigh 127 pounds each.
The investment so far is hovering around $14,000 before the cost of
Assuming you're an experienced do-it-your-selfer, you could probably lay the
shingles and wire them together. But the services of a licensed electrician would
be required to interconnect all the components and make the final connection.
Figure on $500 for the electrician.
The installation cost now brings the grand total to somewhere around $14,500.
When you subtract the maximum Federal Tax Credit of $2,000 the net out of
pocket cost is $12,500. This works out to around $9 per watt ($12,500/1,400
Power production and energy cost savings
Let's see how much supplemental power is generated and what the resulting
cost savings are from $12,500 invested in solar shingles.
According to the homeowner, the average output from the solar shingle system
is 4.7 kWh (kilowatt hours) per day, or 143 kWh a month. The rate charged for
electricity in Ann Arbor, Michigan is $0.11 per kWh. If we multiply $0.11 x 143
kWh, the result is monthly savings of $15.73, or $189 annually. At this rate,
the system would surpass its useful life before it came anywhere near to paying
Here's another way to look at it. If you amortize the cost of the system (after
rebates) over 20 years ($625 per year) and divide that by the annual
production in watts (1716) it is costing the homeowner about $0.36 per kWh
to generate his own electricity - or roughly 3 times what the utility charges.
It's unfortunate that this home owner's enthusiasm wasn't matched by a
similar commitment from the State of Michigan. As of this writing, the State of
Michigan offers no incentives or rebates for residential alternative energy
Solar Shingles Then and Now
Ed. note: First up is the original
solar shingle article written in
2007. Afterwards is an update
outlining the changes that have
occurred in the solar shingle
industry that have led to
improved efficiencies and lower
There's no shortage of praise for
Unisolar's new solar power
shingle technology, especially
from their own web site.
Increased financial incentives
Michigan solar power rebates are now handled through the major energy
company WPPI Energy, which also services the states of Wisconsin and Iowa.
Installations on pre-existing buildings undertaken by a non-certified installer, as
was the case here, would have qualified the homeowner for a $2/kWh rebate,
In total, twenty seven states and several cities now offer incentives in additon
to the federal tax credit that reduce your final cost even more. For more
information check out the Database of State Incentives for Renewables and
Also, the federal tax credit for solar was increased from a maximum of $2,000
to 30% of the total cost with no spending cap. This would have resulted in a
credit of $4350 vs $2,000 on the example installation for a grand total of
$7,782 in state and federal incentives. - an increase of $5,782.
More efficient solar shingles
Alas, the Unisolar shingles praised by Popular Science have been discontinued.
And for good reason. Who wants a solar shingle that produces a measly 17
watts when you have shingles sold by Dow Power House and Certain Teed that
generate 54 watts, are twice as efficient and half the size?
Costs for all types of solar electric systems have plummeted by 45%
The total cost of installation has also dropped dramatically (after incentives)
from $9 per watt a few years ago to an average of $5 per watt today.
Typical residential photovoltaic arrays range in size from two to four kilowatts
— which would be large enough to offset 20%–70% of an average home’s
energy consumption. At $5 per watt, after incentives, a 2kw system would cost
around $10,000 and a 4kw system $20,000.
If you remember, the Michigan homeowner also spent just under $2,000 for a
battery system to store excess power generated by the solar shingles. Now,
with the availability of net metering, excess power generated by the shingles is
sold back to the power company which accomplishes the same end as battery
storage but without the up front cost.
Other benefits of solar powered systems are added value to your home without
incurring additional local property tax assessments and, in many states, a
100% exemption from sales tax on renewable energy technologies.
For more information on sizing a system for your home and estimating the cost
please see Residential Solar System Cost, also on this site.
What a difference a few years has made
in the cost, quality, and efficiency of solar
Had the home owner in our example
waited just a few more years he could
have saved thousands of dollars on his
system with more efficient solar
shingles, increased state and federal
rebates, and the benefit of net metering.
|Dow PowerHouse solar shingles are wireless
and snap together.