Came across this US based solar panel supplier in passing.
Not an ad. I have no financial or other interests in this company and have
never been in contact with them.
They seem to be as price competitive as most for PV panels and offer a wide
range of supporting equipment.

This seems to be a useful site for providing an indication of where US
domestic solar pricing is going - plus some useful technical content in faq
and blog formats. Their lowest $/Watt Sun brand panel prices are approaching
what I've seen recently ex China in small volume.

_____________

Head office in Miami and an outlet in Phoenix.

            http://sunelec.com/

They have their own "Sun" brand panels available ex USA for as little as
$1.98/Watt (100 Watt panel) but more typically at $2 - $3 per Watt range
depending on Wattage and other factors. Their very cheapest Sun brand panels
are said to be cosmetic 2nds but functionally 100%.
They also offer name brand panels (Kyocera, Rec, Evergreen Solar, Sanyo and
Solarworld, ...) usually at higher $/Watt than their own.  They also offer
supporting equipment such as controllers (MPPT and other), batteries,
inverters (grid tied & standalone), chargers etc.

Overall they look and sound good. YMMV. They SAY that their own "Sun" brand
panels are made for them in the US "by one of the world's largest
manufacturers". This may be true - although it would be challenging to
compete with Chinese labour rates unless they have nearly 100% automated
manufacture - which is entirely possible with something like a solar panel.
(I have seen high wattage Chinese solar panels being fabricated under
"cottage industry" conditions with the minimum of automation*, to produce
panels which are visually and functionally (as far as can be told) equal to
any others). (* Large laminating presses and NC controlled LASER PV cell
cutters with otherwise essentially manual fabrication).

The actual PV cells would quite possibly be being made in China, but it is
in fact feasible that they could be made elsewhere due to the necessarily
high automation and material component of the wafer product.

I haven't directly compared the cost of their inverters and other
electronics with eg Chinese offerings, but at a glance they seem somewhat
more expensive than I'd expect.

Their claims for PV panel longevity match those for the industry generally
and they offer anecdotal evidence which implies that some of their early
panels are still running at near full original output after 35 years. This
would be 'extremely good' as actual PV material output will decrease with
age, quite apart from degradation of light transmission and degradation of
the rear anti-reflective layers. Industry claims are typically less than 5%
loss for the first 10 years and less than 10% for the next 10.
(Interestingly this is also what is claimed for optical transmissivity loss
for good quality "properly" UV inhibited transparent Polycarbonate
sheet.)(Inadequately UV protected polycarbonate can can an extremely short
optical lifetime). "Clear" polycarbonate has about 8% optical loss initially
at thicknesses typically used for roofing and this may be slightly lower
loss than the thicker low-iron glass used for silicon PV panels.
Consequently, while EVA-glass is the 'gold standard' for commercial silicon
PV panel manufacture, a well made polycarbonate protected solar system may
perform as well or better electrically than an EVA-glass system.)

A major EVA-glass PV panel longevity factor is the quality of the EVA
adhesive used to bond the silicon cells to the glass. Despite EVA sheet
being widely available in China, to get maximum longevity an experienced
Chinese PV panel manufacture that I have had dealings with uses only EVA
imported from Germany. In many cases country of origin is less important
than the experience of the company involved. Q-cells, arguably the largest
manufacturer of silicon PV cells is German but has manufacturing plants
worldwide including, of course, in China.
_________________

Related:
                   QCells predict that the present 15-16% efficiency of
polycrystalline silicon (PCS) PV material should be able to be increased to
around 18% with expected technology improvements*. Monocrystalline silicon
(MCS) cells are expected to reach 20%+. (Multijunction cells are already
well above that limit and cells for satellite use are higher again due to
the wider available solar spectrum, but such 'extreme' solutions are liable
to be too expensive for mass market use). CdTe cells are already exceeding
10% efficiency, with much lower manufacturing costs, and CIGS cells are also
showing substantial promise - although materials availability and Cd content
are liable to make these competitors to Silicon less viable in the very long
term.

Abundant raw material availability and improved methods means that silicon
may yet be the preferred long term high volume solution. Various "sliced" or
sliver silicon variants offer both lower material costs than existing
silicon wafer PV panels and mechanical flexibility approaching that of thin
film competitors.

Gains from MPPT (maximum power point tracking) controllers are usually in
excess of the expected improvements in polycrystalline silicon efficiency.
(MPPT effectively provides dynamic impedance matching between the PV panel
and load (usually a battery) under varying solar insolation. Depending on
controller cost, use of MPPT to optimise panel efficiency may be cheaper
than paying more for top efficiency cells. The higher efficincies of
monocrystalline cells is offset by a higher price. Whether the higher price
is economically justifiable depends on the cost implications of decreased
panel area per power output or increased output per panel area of MCS
relative to PCS. Where maximum panel area is fixed or smallest size per
power is desirable due eg to wind loading then the extra cost of MCS may be
justified. Where minimum $/Watt matters or where panel area is not overly
important then PCS may be preferable. Mechanical mounting costs increase
somewhat with larger size (larger frames, higher wind loadings and mass,
...).


     Russell McMahon
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