[clug] OT: Solar power recommendations and advice - Certification

Neil Pickford neilp at goldweb.com.au
Wed Apr 21 08:03:21 MDT 2010

Similar to Mikal I have been researching PV Solar/Grid for my own 
application at home.

Be VERY CAREFUL importing panels and grid inverters.
If they do not have Australian Certification and an Approval Certificate 
number then you cannot connect them to the grid...

"The Australian Standard AS/NZS5033, Photovoltaic Installations, Section 
4 states that modules SHALL be compliant with IEC61730 AND either 
IEC61215 or IEC61646." [1] Inverters have to meet AS4777 and AS/NZS3100.

Certification costs in excess of A$10k per product and takes about 8 
weeks.  My system supplier NU energy has just gone thru this process 
with Chinese 250W & 300W Monocrystaline panels from www.nbqxsolar.com. 
Minimum order quantity from this manufacturer is 200 panels.  I need 25.

I am going to use the 250W Monocrystaline panels for a 6.25kW system 
since the panel dimensions when arrayed across the roof area available 
(I'm trying to use it all) provide the best possible output power.

Where space is limited it is best to consider both the $/Watt and the 
power production density (Watts/m2) along with the panel size form factor.

Typical numbers for common panels available in Oz for Grid Solar are:
175W 137.1 W/m2 1580x808 mm
180W 141.0 W/m2 1580x808 mm
250W 148.8 W/m2 1600x1050 mm
300W 154.9 W/m2 1956x990 mm
205W 162.6 W/m2 1580x798 mm

In my case although 300W panels are available and have a better power 
production density (W/m2) I get less power because I cannot fit a 
suitable array of them on the roof in sufficient quantity due to the 
panel dimensions (form factor).

Another gotcha in the ACT - ACT govt wants a planning fee for each phase 
of the power you connect to - so in my case to use a 3 phase Grid 
inverter I have been told I will have to pay 3 planning fees.

Some other interesting technology that IS interfaced to Ethernet is 
available on some other equipment solar I was going to use but which has 
been held up in the above mentioned certification process.

This is a product called POWERBOX [2] from SOLAR EDGE in Israel.  The 
Powerbox replaces the passive DC junction box on the back of each solar 
panel with an intelligent Maximum Power Point Tracker (MPPT) that 
maximises each panels contribution to a string of panels.  This can 
increase the system output by 5-25% making up for panel mismatches, 
shading and under-performance.  The individual MPPT replaces the MPPT 
normally present in the inverter which averages the performance of the 
weakest panel in each string of panels.

Where the inteligent smarts comes in is that each powerbox communicates 
over the DC panel wiring with the Grid inverter and a constant string 
voltage (typically 300+ volts DC) is negotiated between all the powerbox 
devices.  This allows the performance of each panel in the system to be 
individually monitored.  Also full statistics on system performance are 
available for local (home) or remote (utility) monitoring.  This sort of 
equipment should allow some scripted GNU type system monitoring to be 
applied (similar to OWFS/RRDTOOL that I am already running on my Solar 
Hot Water [3]).

Also if the power box cannot see the inverter it applies a max 1V to the 
output (making it safer around the panel DC string wiring when the DC 
breaker/string is open).

I am going to install my system in the next few months with the 
available approved equipment that I can get and retrofit the Solar Edge 
stuff at a later time (when it is certified) to increase the performance.

Neil Pickford

<http://www.solaredge.com/groups/products/overview> Approx US$70 per panel.

Alastair D'Silva wrote:
>> -----Original Message-----
>> From: linux-bounces at lists.samba.org [mailto:linux-
>> bounces at lists.samba.org] On Behalf Of Felix Karpfen
>> Sent: Wednesday, 21 April 2010 1:27 PM
>> To: linux at lists.samba.org
>> Subject: Re: [clug] OT: Solar power recommendations and advice
> <snip>
>> 3 years ago PV panels that used mono-crystalline silicon were
>> considered
>> the best that were commercially available in Australia (and were priced
>> accordingly). Since then thin amorphous silicon films have become
>> readily available. These are much cheaper to produce and hence systems
>> based on them ought to be cheaper to install.
>> Based on my (very limited) search, this does not appear to be the case.
> Yes, thin film in Australia hasn't yet had sufficient demand to really take
> off - the ones that are on the market (like Unisolar) are more expensive as
> they have "special" properties like being flexible, producing more real
> power over time (they don't derate as much as traditional cells), etc.
> If you want thin film panels, the cheapest way to get hold of them is to
> import them - alibaba.com is your friend for that :) You just need enough
> friends who also want them to meet the minimum order quantity from the
> manufacturer.
> --
> Alastair D'Silva           mob: 0423 762 819
> Networking Consultant      fax: 0413 181 661
> New Millennium Networking  web: http://www.newmillennium.net.au
> skype: alastair_dsilva     msn: alastair at d-silva.org
> blog: http://alastair.d-silva.org

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