beautypg.com

Maximum pv short circuit current and nec, Grid tied systems, Solar boost 50 setup – Blue Sky Solar Boost 50L User Manual

Page 16

background image

Blue Sky Energy - Solar Boost 50


15

MAXIMUM PV SHORT CIRCUIT CURRENT AND NEC

To be compliant with National Electrical Code (NEC), solar module controllers should be sized for 125% more rated capacity than
the 25

°C short circuit current (I

SC

) rating of the PV modules. Do not apply more than 40A Isc to the Solar Boost 50.

GRID TIED SYSTEMS

Systems configured to sell excess PV power to the power grid use inverters specially designed for this purpose. In grid tied

systems it is the inverter that actually controls battery voltage and therefore battery charge. Maximum power will be delivered to the
grid if the Solar Boost 50 remains in it’s bulk charge mode while selling to the grid. The key to having the Solar Boost 50 stay in bulk
is to have it’s charge voltage setpoint be slightly higher than the charge voltage the inverter is regulating to. If possible, set the Solar
Boost 50 for two stage charge. If the inverter uses temperature compensation, the Solar Boost 50 must use it as well.

SOLAR BOOST 50 SETUP

¾ Solar Boost 50 has setup options that may need to be configured prior to connection and use. These
setup options are configured by setting a single 12 position dip switch and four potentiometers located on
the main circuit board as shown in Figure 3.

¾ Solar Boost 50 a d’options de paramétrage dont la configuration pourrait être nécessaire avant le
branchement et l’utilisation. Ces options sont paramétrées en fixant un seul commutateur à 12 positions
et quatre potentiomètres situés sur le panneau du circuit principal (Voir Figure 3).

¾ Solar Boost 50 hat Einstellungsoptionen, die vor der Einschaltung und Benutzung konfiguriert werden
müssen. Diese Einstellungsoptionen sind konfiguriert, indem ein einziger 12 Position Schalter und vier
Potentiometer die sich auf der Hauptstromkreistafel befinden wie in Abb. 3, eingestellt werden.

¾ El Solar Boost 50 tiene opciones establecidas que pueden necesitar ser configuradas antes de la
conexión y el uso. Estas opciones establecidas son configuradas mediante un selector tipo “dip switch” y
cuatro potenciómetros localizados en la placa de circuito principal, según se muestra en la Figura 3.

As Shipped Factory Default Setup

• System

voltage................................................................................ 24V

• Temperature

compensation ............................................................ Disabled

Float transition current measurement ............................................. Internal shunt measuring output charge current

• Float

transition current .................................................................... 5.0A

• Charge

mode .................................................................................. 3 stage

• Acceptance

voltage ........................................................................ 28.6V

• Float

voltage ................................................................................... 26.6V

MPPT operating point (V

OC

– V

MP

).................................................. 4.4V Single 36 cell PV module

System Voltage

SWITCH

1

SWITCH

2

SWITCH

3

SWITCH

4

SWITCH

5

SYSTEM VOLTAGE

VOLTAGE SYSTEME

SYSTEMSTROMSPANNUNG

VOLTAJE DE LA SISTEMA

ON [1]

ON [1]

ON [1]

OFF [0]

ON [1]

12VDC

OFF [0]

OFF [0]

OFF [0]

ON [1]

OFF [0]

24VDC

ON [1]

ON [1]

ON [1]

OFF [0]

OFF [0]

24VDC PV / 12VDC BATTERY

It is also possible to wire the PV array for 24V and charge a 12V battery by selecting the 24V PV / 12V battery mode. In this

12/24V operating mode a minimum PV input current of approximately 1.5 amps is required for MPPT to operate and PV voltage to
rise the desired operating point. When MPPT operates, output charge current will be approximately 2X or more PV input current.
This special operating mode can be quite useful for 12 volt systems with very long PV wiring lengths, as wire length can be four
times as long for a given wire size by doubling input voltage and halving input current as shown in Table 3. This operating mode can
also solve problems associated with very high temperature operation where conventional controllers cease to deliver current due to
temperature induced PV voltage reduction. In this mode input current should be limited to 20 amps.

Charge Mode

Solar Boost 50 can be configured for two stage or three stage charging. Typically three stage charge is used, but certain

battery types or system configurations (such as grid tied systems) may benefit from two stage charge. When configured for two
stage charge, equalization still operates as described.

)