Diagrama De Bloques

PV CHARGE CONTROLLER AND FlELD TESTING
Sandía is now working with Momingstar and Dígital Solar Tecbnologies to test lower cost, ímproved performance, and higher reliability charge controllers suchas the SunSaver PWM charge controller and the MPR-9400 microprocessor based PV charge controlIer. Some ex.amples of this work are identified below.
Morningstar SunSaverTM
The development of thischarge controller was partially funded by Sandía as part of DOE's Photovoltaic BOS Program. The SunSaver has been in field tests for over six months. Tbe SunSavernt has demonstmted exceptionaIperformance and relíability for a small (10 amps) low cost PV cbarge controller. It increases charge acceptance in VRLA batteries which should improve VRLA battery cycle-life. The increased chargeacceptance is due to the PWM charge algorithm. Previous work has indicated that improved charge acceptance is possible “ by discharging prior to charging or during the charging process". Figure 8 is an exampleof the PWM charging algorithm in the SunSavernt. The charge and discharge current pulses may be responsible for the improved charge acceptance seen when used with VRLA batteries. Field tests haveshown that the SunSaverTM does provide VRLA batteries with a much higher overcharge or charge acceptance.
Figure 9 is an example of how tbe PV Battery Cycle-Life Test can be used lo evaluate batterycbarge acceptance. In thís test the Momingstar SunSaverTM was placed in series wíth the Firing Circuits antomated battery tester lO mak:e a direct comparison between OC constan! voltage charging and PWMcharging using the same V RLA battery and test progl3IIl for both charge algorithms. This battery survived over 200 cycles ofthe PV Battery CycIe-Life Test before ir "pennanently" 10st over 20% oíits capacity (99 lo 73 Ah). The battery capacity could no! be recovered with constant voltage cbargjng using lb.;.vtmnended chargiug procedures. SunSaver™ PV Battery Cycle-Life Test results now...