Solar Project Update #4

Sorry for the late update, work is back and time is limited once again.

Finally I got the last 2 tools I ordered online:

G.T.Power watt meter and power analyzer

UNI-T UT204A clamp meter

The G.T.Power watt meter can measure the actual power output of the solar panel. The UNI-T UT204A clamp meter can measure DC current with high amperage (for measuring total current going into the GTI).

G.T.Power in action

Measuring GTI's efficiency

Looking at above photo, this is the maximum power output I have seen so far, 330W. Using the volt led meter I mounted and the current it delivers, the input power is 19.4V x 23.27A = 451.438Watts (In DC, VA=Watts).

333W/451.438W = 0.7376 (73.76%) <- efficiency

74% efficiency is very low. My suspicion is correct that the power loss is mostly lost in the GTI. However at low output like <200W, the efficiency is more than 80%. This means that this GTI should only be used at half of its capacity at most to make its efficiency acceptable. My next plan now is to procure a second GTI, this time, I will look for a more efficient brand and has a capacity that is about twice as much as my solar array's output.

There is one more thing I want to mention which regards the cheap watt meter I bought, it's a complete waste of money! Do not buy this or its equivalent look-a-likes. It is not accurate, see the photo below:

3 watt meters connected together

As you can see, the cheap watt meter on front is way off. As of this writing, it is no longer measuring the watts correctly. It shifted to 10x the actual measurement. The 2 other watt meters are my oldest watt meter (kill-a-watt clone) and my 2nd Voltcraft energy logger, both measuring the same wattage give or take 1W.

I could no longer find a source for the kill-a-watt meter and the Voltcraft is sensitive to power surges which I could not use directly on the mains for long periods.  For now I'm using the kill-a-watt but its energy reading is lost when it is unplugged or lost power. I will be on a lookout for an alternative watt meter.

As of Jan 14, this is the current status of my power room:

added mains volt meter and ammeter

The mains volt meter and ammeter will monitor the voltage and current coming from the grid. During the maximum output of the solar array, I have to keep tabs of the current and to make it as close to zero.

Last upgrade to the power room is the exhaust system:

exhaust fans made from 2x 120mm computer case fans

The exhaust fans was installed only last Jan 15. Since I'm at work during the day, I will only know if it's effective on my next rest day this coming Saturday. It's running on 12V and is currently powered using a 1A 220V power supply. It is only using up about 3W only. Once I have an off-grid system, I could hook this up on a 12V battery system which is charged by the solar panels.