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.

Solar Project Update #5

It's been more than 2 months since my solar panels went online and I've gathered daily logs on the output of the PV system as well as our utility meter.

Link to my logs

For January, the total energy produced is 49.3 KWH which is valued about 616 PHP. This is the amount saved from our utility bill. Our billed KWH for January 2014 is 380KWH, this means we were able to reduce the consumption by more than 10% and my objective for phase 1 was fulfilled.

For February, the total energy produced is 45.66 KWH, it's less than January but considering Feb have 3 days less than Jan, its daily average is higher. Our billed KWH for Feb 2014 is 352 KWH. We were able to lessen our energy consumption by replacing some of our CCFL light bulbs into LED light bulbs. One CCFL is rated at 11W and we replaced it with a 7W LED bulb and it's even brighter!

As of this writing, my replacement grid tie inverter is en route and should arrive by next week. Once installation is completed, it will be marked as phase 1b and an increased energy output is to be expected.

Phase 2 of the project will consist of a new PV array but this time it will use a string grid tie configuration. Tentative capacity will be 2KW and the objective is to reduce utility bill up to 50%. However,  phase 2 is many months away, maybe on 2015 but I'm hoping it can be done earlier. The decision to go grid tie again is because I found out that our utility meter is bi-directional and should be no problem when the PV system will produce more energy than what we consume at daytime. Installing an off-grid system is still on the table for cases of power outage and as backup in case our meter is damaged and will be replaced by a one-way meter.

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.

Solar Project Update #3

Last Jan 3 I went back to Raon to find some needed items for the project as well as have my watt meter repaired. I found cheaper sources of circuit breakers and MC4 connectors there and found the terminal bus bar I was looking for.

terminal ratchet crimping tool

The terminal bus bar is used to connect multiple wires without twisting them together or soldering them. I will use this to both positive and negative of the solar array until the circuit breakers arrive.

terminal bus bar

I have the yields for Jan 3-4 and here they are:
Jan 3 = 1.8327kwh
Jan 4 = 1.8458kwh
They were much better than on the first day which is only 1.454kwh.
Unfortunately, I still have not seen the array produce more than 300W during mid-day even tho the solar panels have the capacity of 600W, that's a loss of a little more than 50%. This is something I'm disappointed and until the rest of the tools I ordered arrived, I won't be able to do a through check to find where the losses are coming from.

TO DOs:
I also still need to work out the ventilation for the power room, it is unbearably hot there during the day.
To summarize the things to do:
1. Panel board permanent fixtures
2. Power room ventilation
3. Improve efficiency of the solar array

ROI:
Here are the assumptions:
yield = 1.8kwh/day
grid cost = 13 php/kwh
cost of solar system = about 50k php.

1.8 kwh/day x 30day/mo = 54 kwh/mo
54 kwh/mo x 13 php/kwh = 702 php

702 php/mo is how much the array is producing per month assuming all days are sunny days.

50,000php / 702php/mo =  71.225 mo
71.225 mo / 12mo/yr = 5.9 yrs

ROI (return of investment) will take more than 6 yrs for the system to pay for itself but this is assuming all days are sunny days so it will take longer. However, if the utility company increases the cost to 17 php/kwh, the ROI will drop to only 4.5 years.

Since this is a grid tied system, the ROI is computed based on the assumption that all the energy produced by the solar array is consumed and no excess is sent back (exported) to the grid. Just to give you an idea how net metering is implemented in Philippines, the value you export to the grid is worth only about half of what you consume from the grid. So if say you consume 10kwh during the night, you'll need to export 20kwh during the day just to break even on the bill.

For more information about net metering here in Philippines, please read this free PDF guidebook:
Download from this mirror link in case the primary link is down.

Solar Project Update #2

Continuing where I left...

It is Dec 30 morning and I went up the roof to see the progress and I saw 5 panels mounted exactly to my specifications:

5 solar panels mounted on an elevated iron rail. 

The 6th panel wasn't mounted yet until the wiring has been laid down because the wiring entry lies below the 6th panel (shown in above photo). I asked to placed it under as the wires we used isn't meant for outdoors so it can be protected from direct sunlight.

After a while, we've started laying down the wiring from the solar panel. To connect from the solar panels, you need to use a standard connector called an MC4.

MC4 connectors

We used a stranded 2.0 sq. mm wire (AWG#14), I think is was too thin but this is what we have in my dad's stock. Looking up the current limit of AWG#14, it current capacity is 5.9Amps which is just enough for each of our solar panel. We also have only one color which is red so I used a marker to mark each end to identify which is which.

AWG#14 wire with MC4 on one end and laid to ground

All the wires needs to be threaded in the conduit on one go so they needed to be tied up and once it was done my dad went to the roof with the bare end of the wires and I went to the attic to catch the wires through. Once it's done, the wires were inserted in a plastic orange flexible tubing. The end of the wire stops in the proposed power room. The 6th solar panel was installed shortly.

wires connected to the solar panel

We also laid out a pair of AWG#10 wire from the grid main distribution box and connected to a pair of circuit breakers. These wires were also inserted to a plastic orange flexible tubing. The end of the wire stops in the proposed power room. This will be where the output of the GTI will be connected. It is late afternoon already so we call it a day.

Dec 31, it is new year's eve but we still worked on the project. I still do not have yet the needed equipment for the power room like the disconnect switches, etc. I ended up ordering them online as finding them locally will take some time and I have to wait out the entire holidays, and I can't wait for it. I also ordered online the much needed DC current clamp meter. Both will be shipped via express shipping. So while the equipment arrives, we rigged a temporary connection. Luckily, everything is available except for an AC outlet and its cover so I went out on a holiday and fortunately, there is an open family hardware store which sells them and I bought it.

GTI finally connected (temporarily) to the solar panels

By mid afternoon, we have completed the circuit. I went back to the roof and took this photo:

Roof mounting is complete

That night, fireworks have began. I went back to the roof near the solar panels near 12 midnight and shot this video:

Happy New Year!!

January 1, new year's day and it's the first day the grid tied solar array system went online for a whole day and I monitored the power output using the watt meter:

Watt meter measuring 260W output power during mid day.

Here's the monitored power output throughout the day:
6:45am  17w
7:00am  46w
8:00am  156w
9:00am  211w
10:00am  242w
10:30am  260w
11:13am  267w
11:30am  280w
12:40pm  262w
1:00pm  236w

Total energy produced for Jan 1 was 1.454kwh

Jan 2, today, I used my other watt meter instead, the Voltcraft brand. By noon, during it's peak output power. I noticed the watt meter is displaying 0 output and the GTI is not recycling, usually it recycles in 1-2 secs after it detected a change in solar output. I turned off the GTI and back on and then it recycled. Seeing that is was unusual, I simulated a power outage by turning off the AVR (automatic voltage regulator) where the GTI output and watt meter is connected and turning is back on. I got startled when I heard a weak 'pop' in the watt meter and the display did not turn on. Guess what, the watt meter is busted! My guess this Voltcraft meter does not like power surges, it was damaged one time during its warranty period and I got it back repaired. I will try to have it repaired again this time out of warranty. Fortunately, nothing else is damaged so I installed back the cheap watt meter and put the GTI back online.

Due to that incident, I have no output data for today.

I will make another update once new equipment have arrived or there is new progress.

Solar Project Update #1

Ok for the first update, I'll share some photos of what I have so far on the project.

500W Grid tie inverter

The grid tie inverter is the first device I acquired from an online local seller. Acquired it last Dec 14. So far it works during testing by connecting it to a car battery while the engine is running. I was only able to produce 210W tops, not sure what is keeping it from producing more power. Maybe it's because the battery is small or the connecting wires aren't thick enough but it's enough to confirm the device is functional. How did I know it reached 210W? I used a watt meter and I'll introduce it later.

500W grid tie inverter specs:
DC Maximum Input Power - 600W
DC maximum voltage - VpvDC30.2VDC
DC voltage range - Vpv 10.5V~28VDC
Maximum output power factor - 99%
Maximum input current - 30A
AC output power - 500W
AC maximum output power - 500W
Anti-voltage protection - Fuse
AC standard voltage range - 180~260VAC
AC frequency range - 50HZ~60HZ

One thing I should point out that grid tie inverters (GTI henceforth) does not work when there is no grid power. When there is a power outage on the grid, the GTI automatically turns off, this is called anti-islanding and it's meant as protection to the person servicing the electrical system.

Tools

During the course of the project, I will need to use tools. Some of the tools I already have and some needs to be purchased. The cost of these tools will not be taken into account when computing for the return of investment (ROI henceforth) as tools have their own ROI each time they are used for many projects.

One of the tools which I already have is the watt meter:

Watt meter 

This watt meter was bought a few years ago which I used to monitor power consumption of various appliances including the air conditioner. It can measure wattage up to 3500W. It can store data in an sdcard and can graph the energy usage using a software included with the device. However, I won't be using this once the GTI goes into normal operation since this device is sensitive to power surges. I had this serviced once due to power surges. I bought a cheaper watt meter instead for this project:

Cheaper watt meter

Another must-have tool is the clamp meter. During my recent visit to Raon, I found a very cheap clamp meter. Since I badly needed a clamp meter to verify the GTI is indeed slowing our power consumption from the grid, I bought one:

Cheap clamp meter

This clamp meter only works in measuring AC current. It cannot measure DC current via the clamps and I will also need a clamp meter which can read DC current to measure the solar panels output current. I'm currently on the lookout for a better clamp meter. 

Last but not the least must-have tool is my digital multi-meter (DMM) which I bought many years back:

good old DMM

Back on the project...

On Dec 27, the solar panels have arrived:

100W solar panel

This is one of the six panels I ordered online (it's cheaper and better quality from Raon varieties), note my DMM on the upper left of the photo, I used my DMM to see that the panel is producing up to 24V.

The panels are to be installed on our house roof so I asked the help of my dad for the metal works. Initially, I plan to put up aluminum mounting but after consulting with dad, he and I decided to go with iron mounting.

Roof status as of Dec 27

The solar panels will be mounted on an elevated rail instead of laying flat against the roof. This will help on cooling the solar panels as heat reduces its power output. 

On Dec 28, while the roof mount was still under construction, I tested one solar panel just laying flat on the roof and connected it on the GTI and measured the output using the watt meter and here are the data I got:

8:45am - 56W

10:13am - 75W
around 12nn - 82W
around 1pm - 66W
around 2pm - 54W
around 3pm - 45W

Total energy produced  - 249WHrs

The measured Watts is only the peak power it shown at the time, power fluctuates constantly specially when there's a cloud passing between the panels and the sun. After 3pm, I'm already getting shadows from our mango tree and the output drops and causing the GTI to recycle and cannot produce more than 20W anymore. Please note that for each solar panel, there should be no shadow casted on any of the cells, if there's one cell that is shaded, the entire panel output will drop to near zero, this is because the cells are connected in series, the solar panel with only be as strong as its weakest cell. The energy produced for the whole day is much lower than I expected, this is due to the weather on that day which is only partly cloudy. This causes the GTI to recycle when the sun gets blocked by clouds many times during the day.

On Dec 29 Sunday, I have work duties so I was not able to take photos of the roof mountings but my dad continued with the metal works and by the end of the day, 5 solar panels have been mounted as well as the wiring conduit through the roof.

Tomorrow we shall work with the wiring from the solar panel to the attic in which a part of it will become the power control room.

New project

Hi,

It's been a while since my last blog. On my last project, the Raspberry Pi project, I've made a total of 3 RPi devices. The third was only completed recently and it's for our media center for the living room. My 4th RPi is still stored for future use, as a backup or maybe a development unit.

Moving on, with the current power rate hikes rising to record level and the government's implementation of net metering. I've decided to invest and setup my own solar power project.

typical roof mounted solar panel

Last week I've bought the first device, a 500 Watts grid tie inverter. What this does is produce energy and fed it directly to the power grid  (Meralco). No need to purchase batteries to store energy. Example, if at daytime we are consuming 600 Watts of power and the grid tie inverter is producing say 400W, then we will only consume 200W from the power grid.