Solar Project Update #6

In my last blog, I mention that my replacement grid tie inverter (GTI) will arrive a week after. It did arrived but late on April 4 and I immediately proceeded to install it.

New GTI above, old GTI below

The new GTI is 1000W. My old GTI was only 500W. I intentionally acquired a much bigger wattage compared to my PV total wattage so that its load is only about half to maximize the output efficiency.

Since this GTI has DC input range of 22-65VDC, I had to rewire the PV panels from parallel to series-parallel where pair of PV is in series and then connect the pairs in parallel to double its output voltage.

On the first day of its operation, I already exceeded my record high output. My record high power output on my old GTI is 330W. On the new GTI, I have monitored a record high of 463W! For the record high daily energy output on my old GTI, it was 2.3KWh, on the new GTI, it was 3.24KWh right after cleaning the PV panels. I am very satisfied with the results.

As for the efficiency of the new GTI, I obtained the ff data:
IN: 500-503 , OUT: 447-448 eff: 89.6% 4/4/14 10:50am  (using R.C Power watt meter)
IN: 35.1V,14.6A, 512.46W OUT: 460W eff: 89.7% 4/4/14 11:31am (using UNI-T multimeter)

Efficiency is almost 90%. The advertised peak efficiency is 92% and I got quite close.
Also by reconfiguring my PV panels, I've also increased my PV output and have now produced >500W. Previous PV output was about <430W only.

My solar output log is still updated daily and you can see the detailed results there. (link is in Solar Project Update #5 blog)

With the solar output now at satisfactory level. I shall place the permanent fixtures on my panel board like the DC switches and a dedicated watt hour meter for grid tie output.

Since it is summer now and an occasional brownout are to be expected. I want to setup a small off-grid system to make use of the PV panels while there's no utility power for a short duration. This will be my next plan. I shall make use of our existing CDR-King 300W modified sine wave inverter and my semi-defective 1500VA UPS. I will need to purchase a pair of batteries about 100AH each and a charge controller. I'm still researching for sources of reliable deep cycle batteries. Motolite Solar Master isn't a good choice based on some infos I gathered. NPP VRLA batteries seems a good option but I'm yet to find a reliable source. If you have recommendations, please leave feedback below.

Update: I forgot to mention that I already sold my old GTI so my loss is minimal. One thing I noticed on solar projects is how easy it is to sell your old equipment. It just shows that there are lot of demand on renewable energy and the costs will just go down as time goes on while fossil based energy goes up.