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SMA Solar Technology AG September 2013
Technical benefits of String Inverter Technology
Mark Ryder
SMA Solar Technology AG
1 String inverter concept
Benefits of String inverters
Agenda
2
3 Low light conditions
2
4 Shading Management
5 Derating curves
6 Communication & Monitoring
7 Summary
SMA Solar Technology AG
String inverter concept and applications
3
Residential and small commercial sites:- Small string inverters (usually
single phase), the entire PV array can be just one string
Medium-size systems (50kW-250kW or more): commercial roofs, warehouses, farms... - Decentralised designs using
three or four strings connected to the inverter (mainly three-phase)With different oriented sub-arrays or shading
issues, the string inverter concept enables better power-related adaption to the irradiance conditions
SMA Solar Technology AG
1 String inverter concept
Benefits of String inverters
Agenda
2
3 Low light conditions
4
4 Shading Management
5 Derating curves
6 Communication & Monitoring
7 Summary
SMA Solar Technology AG
> Easy transport and installation
> Wide range of power classes available:
• Single phase
• Three phases
> Flexible designs (different orientation and
inclination): 2xMPPT's, OptiTrac...
> High Efficiency
> Easy maintenance
> Reliable
> Easy monitoring
Benefits of String inverters
5
SMA Solar Technology AG
1 String inverter concept
Benefits of String inverters
Agenda
2
3 Low light conditions
6
4 Shading Management
5 Derating curves
6 Communication & Monitoring
7 Summary
SMA Solar Technology AG
Low light conditions
7
> In countries with low levels of radiation, such as the UK, with less
than 1250kWh/m2 year, the efficiency curve for lower power
becomes more important.
SMA Solar Technology AG
1 String inverter concept
Benefits of String inverters
Agenda
2
3 Low light conditions
8
4 Shading Management
5 Derating curves
6 Communication & Monitoring
7 Summary
SMA Solar Technology AG
Shading Management
9
> It is not always possible to prevent shadows on PV plants.
> The loss must be minimized already in the planning phase.
> Influential factors:
> arrangement of the PV modules
> connection of PV modules
> the choice of the right inverter
Selecting the system connectionSevere shading: operate shaded and unshaded PV modules separately.
‒ No parallel connection of strings with different irradiation
2xMPP Tracker inverters
‒ The MPP tracking concept of the inverter is decisive to maximize the energy yield.
Improved MPP trackers can find the optimum operational point, the global MPP: SMA
OptiTrac Global Peak
SMA Solar Technology AG
1 String inverter concept
Benefits of String inverters
Agenda
2
3 Low light conditions
10
4 Shading Management
5 Derating curves
6 Communication & Monitoring
7 Summary
SMA Solar Technology AG
Derating curves
11
> The inverter reduces its power to protect components from
overheating.
> The correct design of a PV plant must not completely exclude
derating.
> High temperatures and overheating can occur when inverters are
mounted in commercial closed plant rooms with low ventilation
Best practices:> Install the inverters in cool locations
> Sufficient air exchange
> Not under direct sunlight
> Minimum clearance between inverters
> Select an inverter with good derating curves
SMA Solar Technology AG
1 String inverter concept
Benefits of String inverters
Agenda
2
3 Low light conditions
12
4 Shading Management
5 Derating curves
6 Communication & Monitoring
7 Summary
SMA Solar Technology AG
Communication & Monitoring
13
> Monitoring ensures that failures or faults are quickly detected
> For medium and large size systems a data logger is required
> New technologies allow faster communications
(Webconnect/Speedwire)
> With internet-base monitoring systems, a service provider takes over
the evaluation of the operating data.
SMA Solar Technology AG
1 String inverter concept
Benefits of String inverters
Agenda
2
3 Low light conditions
14
4 Shading Management
5 Derating curves
6 Communication & Monitoring
7 Summary – SMA Case study
SMA Solar Technology AG
Summary
15
> Wide range of string inverters depending on the application:
> For complicated commercial roofs:
> Shading issues, difficult configurations: standard Sunny Tripowers
(with 2xMPP Trackers and OptiTrac Global Peak)
> Easy and simple commercial roofs (cost-effective systems): Sunny
Tripowers-project version
> Useful for East-West configurations too: polystring concept
SMA Solar Technology AG
SMA solution for commercial roofs:Unique Project Performance Package
16
>Sunny Tripower 20000 TLEE PROJECT – gains highest yields
>Cutting edge high speed communication– optimises the plant control and gives full visibility
INVERTER
COMMUNICATION
>Commissioning package – secures your investment
>Remote Service – reduces transaction cost
>99% Availability Guarantee – insures your ROI
SERVICE
>> This is unique in the market and only offered by SMA.
SMA Solar Technology AG
SMA Case study
17
Sunny Tripower inverters complete your projects with the all the
benefits of string inverters:
> High efficiency (over 98%) under low light conditions
> OptiTrac Global Peak and 2xMMP trackers for shading
management
> Good derating curves
> Easy and fast communication & monitoring with SMA devices
> Reliable and easy maintenance
SMA Solar Technology AG
THANKS FOR YOUR ATTENTION
18