Sanyo panel & CControllers [RE-wrenches]
Larry Crutcher, Starlight Solar
larry at starlightsolar.com
Mon Feb 4 16:26:44 PST 2008
Why don't the manufacturers of MPPT controllers just put a brick wall voltage clamp on the input? (Of course the answer is cost) A touch of hysteresis here and some time delay there and Voilà! It would be great to have 2 Sanyo's wired in series. For the occasional few times a year that over voltage could occur, high voltage is prevented from reaching the input to do any damage.
My 19 Won or about 2 cents worth.
Larry Crutcher
General Manager
Starlight Solar
Retail Store & Shipping: 2998 Shari Ave. Yuma, AZ 85365
Phone (928) 941-1660 Fax (928) 342-9103
Mailing Address:11279 S. Glenwood Ave, Box 11114, Yuma, AZ 85367
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----- Original Message -----
From: Christopher Freitas --- OutBack Power
To: RE-wrenches at topica.com
Sent: Monday, February 04, 2008 3:54 PM
Subject: RE: Sanyo panel & CControllers [RE-wrenches]
Tump - I agree that reliability is the most important part of any
product - but its something that we can (and do already) know how to
achieve for a product like this...
What I was talking about the engineering challenge of developing a high
voltage input MPPT product - that the converter's efficiency has to be
high enough to justify its cost - if the MPPT is only 95% efficient than
it might not "capture" much additional power for most of the year from
the PV array. Also, If the system has a 3000 watt PV array and it cost
$5/watt to install - then each single percent of the MPPT's conversion
efficiency is worth $150...
The greater the difference between the PV array and the battery voltage
- the lower the efficiency of the DC-DC converter. Sure - there are
tricks that can be done to reduce these losses - but they tend to make
the product much more expensive - again reducing the overall "value" in
the end.
The bottom line is everything has trade-offs. Higher voltage MPPTs will
cost more, will be less efficient, and will be lower power than the
current MX60 & FM80. They can reduce the system installation cost by
requiring fewer strings, smaller wire, smaller conduits - but only time
will tell what wins out in the end...
There also is the option of doing AC coupled systems with grid-tie
inverters - which allows for up to 600 VDC PV arrays right now - but a
3000 watt grid-tie inverter is over $2000 - which would pay for a fair
amount of additional wire and labor... and most of the grid-tie
inverters are only 95% or so efficient...
Christopher
Christopher Freitas
OutBack Power Systems, Inc.
cfreitas @ outbackpower.com
www.outbackpower.com
Arlington WA USA
Tel 360 435 6030
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