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Lloyd’s roof-mounted solar panels (image via Extreme Tech)

In response to a Slashdot / Extreme Tech article about a $60,000 residential PV system that still leaves its owner with $200 per month winter power bills, Mikey Sklar posted the following tips:

1. Roof Mounted Panels Suck – They often have limited or no tilt
control and clumsy to maintain. This means that you will likely get
strong performance in summer or winter, but not both. Finding the
average latitude tilt for your region and mounting the panels at that
angle is your best option for roof mount. Trackers can bring your
performance up by 1/3rd, but will include extra expense and
complexity. Consider a manual tracking system which you just push with
your hands through out the day if you need a early morning or late
afternoon boost. This is ideal for the off-grid / unemployed eco-geek.

2. Grid Tie has issues too – Although grid-tie allows a PV install to
greatly reduce their installation time and costs they also have some
drawbacks. Continuing to buy power from a power company can result in
relatively high monthly fees if the system purchased was undersized.
Many grid-tie installations have no battery backup so when the grid
dies, you lose all your juice too. In remote towns many power
companies only pay the customer a 1/4 of what they charge the customer
for power. My town being unusually behind the times refuses to
purchase any power from their customers.

3. PV Batteries – New batteries are easy, but old ones can be fixed.
Our world is hemoraging so called “dead cycle batteries”. Try talking
to your local golf course, marina, or auto parts store. As you learn
to test cells and repair lead acid batteries through desulfation you
can save yourself a fortune in batteries and store large amounts of
energy. Keep in mind that batteries are much like people. They like
72F temperatures and a little exercise. Do not cycle the batteries
below 50% on a regular basis. I try to stay over 70% capacity on my
battery array at all times.

4. Heat – My panels tend to have a pretty big drop off in performance
during the summer. This is partly due to my not adjusting the PV array
to be almost flat during June. It is also related to our monsoon
season bringing in lots of rain and cloudy weather. However, the real
killer of performance is the temperature. High temperatures drop my
panel performance by 30%. Our temps in June sit peak around 100F in
June which is enough to dramatically reduce the performance on a
polycrystal PV cells. The monocrystal cells are supposed to handle the
higher temperatures better.

Thanks Mikey (and Lloyd!)


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