[RE-wrenches] Off-grid in Tanzania

[Andrew Truitt]

Wrenches - I am working with Lee Bristol and Ray Walters on 20 off-grid PV
systems in Tanzania at various types of remote health care facilities.
 There will be 3 system offerings: 2, 4, and 6 kW, all 230V, 50Hz.  We are
currently considering the following issues and would appreciate input:

   - *AC coupled SMA system vs. DC coupled Outback/Midnite system*: We have
   had positive experiences with Sunny Boy / Sunny Island systems in GT w/
   battery back-up applications and we like the SMA production monitoring
   (more on that later), but we are not sure how appropriate the system is for
   off-grid.  Cost is a consideration, as well as energy harvest, simplicity
   for in-county technicians, future system expansion, battery SOC remote
   monitoring, integration of generators, running power to multiple buildings,
   inverter over-sizing to increase equipment lifetime, reliability, battery
   over/under-charging prevention, ease of use for the customer, surge
   capability, and programable load shedding.  We have had numerous internal
   discussions about this particular decision and would appreciate additional
   viewpoints.
   - *Ground mount vs. Pole mount*: The roofs at the sites are far from
   ideal in both construction and solar access so we are planning to locate
   all the arrays on the ground.  Soil types and slopes vary.  Manual labor
   will be readily available but heavy equipment will be hard to come by.  We
   would like to have a standard, replicable system which might be more
   achievable with a pole mount (e.g. [8] 250W modules per pole for 2kW; 1, 2,
   or 3 poles per system), and poles might be easier to have pre-installed
   before we arrive (e.g. you can't get the orientation wrong; less spacing
   measurements to consider), but the cost difference is significant (about
   $0.40/watt for S-flex ground mount vs. $1.05/watt for DP&W TPM all in).
    The pole mount would be adjustable (east/west to account for micro-climate
   variations, north/south for seasonal adjustments), but how much of a value
   does that add at 10 degrees south latitude?  A ground mount could be
   ballasted which could be a big benefit in some locations.
   - *Monitoring options*: This is a tough one.  Obviously there is not
   robust internet access so we are looking at cell modems for data
   transmission.  Does anyone have a recommendation for a 3rd party off-grid
   full system remote monitoring provider?  Pentametric is an option - anyone
   have experience with the on-line interface or remote monitoring
   reliability?  All the OEMs have monitoring options for production and
   battery SOC, but we want to have an additional system to compare data and
   provide redundancy.

Clearly there are many more factors that go into these decisions than I
have conveyed here, but we are just hoping to get some thoughts on the
issues from the extensive off-grid knowledge base on this list,
particularly from anyone with experience in Africa.

Thanks in advance!



For a brighter energy future,


Andrew Truitt

Principal
Truitt Renewable Energy Consulting, LLC

(202) 486-7507

LinkedIn Profile <http://www.linkedin.com/pub/andrew-truitt/8/622/713>

Company Website <http://truittreconsulting.weebly.com/>

NABCEP Certified PV Installation Professional ID: 032407-66

Colorado Journeyman Electrician License No.: 600132

 <%28202%29%20486-7507>

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"Don't get me wrong: I love nuclear energy! It's just that I prefer fusion
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ever use in just about 8 minutes. And it's wireless!"

~William McDonough
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