GI System Diary

System Performance Data
GI System Main Page

Here is a diary outlining some of the trials and tribulations I've experienced with my Grid-Interactive PV System.

15/8/00

System installation of eighteen 75 Watt panels completed. Original panel configuration: 3 parallelled sets of 6 series connected panels - 2 sets mounted on the house roof with an azimuth of 35 degrees west of true north and fixed elevation of around 30 degrees, and one set (3 panels mounted on each of 2 frames) positioned on the carport roof facing true north and adjustable elevations of 20, 34 and 55°.

Problems noted:

(1) Over-voltage protection relay dropping out and not automatically resetting. Often very difficult to reset even manually. On some days it just wouldn't reset. Several attempts were made to adjust the cut-off threshold, but to no avail.
(2) Inverter's serial data interface not working
(3) Intermittent fault with inverter where on several occasions it was producing a lot less power than it should have been. Cutting DC input so the inverter shut down then re-applying the DC fixed the problem on occasions when the problem was observed (may have happened at other times as well).

7/12/00

New protection relays fitted.

23-29/12/00

New protection relays tripped a couple of times and didn't reset. (Relay failed mid afternoon 23/12 and was reset late 27/12, then failed again on 29/12). Cut-off threshold adjusted slightly which seems to have fixed the problem.

28/12/00

Highest daily amount produced - 6.5 kWh.

Problem noted:

Max Peak wattage generated on any day was 940 Watts - A fair way short of the 1350 Watts that should be possible. Overall figures also lower than expected.

It was found that the incorrect documentation had been supplied with the inverter. The maximum DC input current the inverter can handle is 9.0 amps. Each 75 W panel (and hence, each series connected set) is capable of nearly 4.5 Amps peak, so with three sets in parallel, the potential maximum current was close to 13.5 Amps. The inverter has maximum power-point tracking, and can handle DC input voltages from 75 to 276 Volts. By changing the panel config from 3 sets of 6 series connected panels to 2 sets of 9 series-connected panels, the peak current would decrease from just under 13.5 Amps to just under 9.0 Amps and the voltage supplied by the panels would increase from around 102 Volts to 153 Volts (assuming 17.0 Volts per panel). It was decided to give this configuration a try.

16/01/01

Panel configuration changed as per above. The down side was that now panels on the house roof were connected in series with those on the carport roof which were in a slightly different plane. The maximum current produced would be limited by whichever panels had the weakest exposure. Immediately daily peak powers rose from around 850 Watts to around 1200 Watts. Highest peak of 1250 Watts noted on the 01/02/01.

Highest daily figures before & after change:
week before:	6.0 kWh	week after:	5.9 kWh
month before:	6.5 kWh	month after:	6.1 kWh

22/01/01

Inverter changed. Problems (2) and (3) mentioned above have not re-occurred since.

01/02/01

Highest peak power observed - 1250 Watts.

20/04/01

The system become accredited to generate RECs (Renewable Energy Certificates). Each MWh generated after this date is equivalent to 1 REC.

26/05/01

Panel configuration changed - 9 house-roof mounted panels connected in series, 6 carport-frame mounted panels + 3 house-roof mounted panels in series.
Note : Daily max figures for the month before & after not displayed because at this time of year a wide variation would normally be expected, and wouldn't be indicative of the changes made.

Highest daily figures before & after change:
week before:	4.5 kWh	week after:	4.5 kWh

30/06/01

Panel configuration changed - 3 house-roof mounted panels moved to a new frame on the carport. Parts for the frame cost about $200. This leaves me with 9 series connected panels on adjustable frames on the carport, and 9 series connected panels fixed to the house-roof. All the series connected panels are now in the same plane.

Highest daily figures before & after change:
week before:	4.3 kWh	week after:	4.7 kWh
month before:	4.3 kWh	month after:	5.0 kWh

Problem
noted:

As can be seen from graphs, the amount of power produced was dipping in the middle of the day. This only seemed to occour from the end of August to early April (?), when Idc exceeded about 8 amps. The inverter was also dropping out for a minute or so at a time. This appears to be related to the Mpp tracking losing the plot and the voltage going up from its normal 130-140 Volts to over 170 Volts, and then giving up.

12/01

In case the problems mentioned above were heat related, I tried to improve air circulation around the inverter by installing a vent at the top of the enclosure, and installing a couple of solar powered fans to draw the warm air away from the unit. However, it doesn't seem to have rectified either problem.

21/12/01

First REC generated (ie 1 MWh of power produced since 20/04/01).

Problem
noted:

LCD display on unit stopped working. Nothing else seemed to be affected.

05/02/02

Inverter removed in the evening of 05/02, and sent in for repair. Replaced in the evening of 12/2/02. LCD unit was replaced, but no reason could be found for either the power dipping in the middle of the day or the inverter dropping out intermittently.

09/02

2nd REC generated.

Problem
noted:

Power still dipping in the middle of the day, between approx August & April.

19/11/02

Inverter removed, and sent in for repair. It took seven weeks (and quite a number of phone calls) to get it back. Inverter re-installed on 5/01/03.

Problems
noted:

(1) Inverter producing about 60-70% of the power that is was before.
(2) The kW readings weren't being recorded or displayed on the inverter. Any readings had to be taken from the external meter.

30/01/03

Inverter removed, and sent in for repair. After 3 weeks, the inverter was returned and re-installed on 21/02/03.

Problems
noted:

(1) The serial interface didn't work
(2) The day after the inverter was re-installed (22/02/03), it stopped working. No signs of life from the unit.

06/06/03

Inverter finally returned to me. On initial re-installation, it didn't work. A quick inspection revealed a spade lug connection had become dislodged. After plugging it back in, the inverter started generating power...Yeah!! The Serial interface is still not working, but I've decided after all the stuffing around and the system being off for the last 7 months, I'm prepared to live with that one.

16/09/03

Inverter still has original problem where power is dipping in the middle of the day. It's not therefore generating as much power as it should, but on average it is still generating more than I consume.

17/12/03

Inverter dies - No signs of life. Sent in for repair.

25/02/04

Inverter returned with new main board. Re-installed - Inverter & Serial Interface working. Power is still dipping in the middle of the day.

Last Updated: 20/05/04