How about a solar car port on a budget?

[Crossy]

11 hours ago, BritManToo said:

I predict the 345w panels will damage the 300w panels.

 

They have very similar max-power and short-circuit currents, the 345W units are slightly higher max-power voltage, both recommend a 20A fuse. I doubt there will be any serious problems, we shall see.

 

It's a few minutes work to move the two 345W panels over to the other string, I may do that later today.

[Muhendis]

15 hours ago, Crossy said:

 

They have very similar max-power and short-circuit currents, the 345W units are slightly higher max-power voltage, both recommend a 20A fuse. I doubt there will be any serious problems, we shall see.

 

It's a few minutes work to move the two 345W panels over to the other string, I may do that later today.

I don't know how these strings are configured so assuming you have them arranged as two strings of nine then, adding two more, they would become two strings of ten. There will be no problem except that you will not realise the full power of the 345W units. The new 345W panels would be current limited by the rest of the string. I am also assuming you have taken the additional voltage into account.......

[Crossy]

32 minutes ago, Muhendis said:

I don't know how these strings are configured so assuming you have them arranged as two strings of nine then, adding two more, they would become two strings of ten. There will be no problem except that you will not realise the full power of the 345W units. The new 345W panels would be current limited by the rest of the string. I am also assuming you have taken the additional voltage into account.......

 

It's a string of 8 * 345 half-cell and a second string of 8 * 300 + 2 * 345 full-cell panels.

 

I suspect changing the full-cell 345W units to the other string may be a good idea from the capacity point of view but I doubt any actual damage will occur to the 300W panels.

 

The inverter has independent MPPT controllers on each string so mis-matched strings are not an issue.

[Muhendis]

Ah yes. I understand now. The picture on  your roof earlier included the two 345W panels. 

1 hour ago, Crossy said:

I doubt any actual damage will occur to the 300W

Absolutely right.

[Crossy]

Well, we've had our "final" configuration for a whole week now.

 

Despite having a stormy day it's averaged 27.5 units per day.

 

Total expenditure on what we are using (ignoring the currently unused micro-inverters) is about 88,279 Baht. 

 

With net-metering that gives us a payback period of just under 2 years.

 

Obviously we're not going to be generating at that rate all year but it does give a very sensible return.

 

[Muhendis]

14 hours ago, Crossy said:

With net-metering that gives us a payback period of just under 2 years.

What does the term "net-metering" mean?

[Crossy]

17 minutes ago, Muhendis said:

What does the term "net-metering" mean?

 

We are not a member of the government scheme, when we are exporting power our (mechanical) meter just goes backwards racking up credit for when we put the aircon on at night. So effectively we are using the grid as our "battery".

 

Despite the fact that there are many hundreds, probably thousands of grid-tie systems in Thailand working this way net-metering is not officially permitted. In fact a number of members have been caught out and had no-reverse meters fitted.

 

I'm mitigating getting "caught" by ensuring we are not exporting on meter reading days (usually the 17th, occasionally 1 day either way) so the meter reader doesn't see the beast going in reverse.

 

EDIT On average we are "storing" about 11 units per day in the grid for use later when the sun is sleeping. If I had to store that energy in batteries it would need about 200Ah of available storage at 48V. A battery of that magitude would cost the best part of 3 grand US (LiFePO4) plus a suitable hybrid inverter for about 1,500 US.

 

 

[Crossy]

As promised, details of the "no export" controller.

 

Our inverter has the function to control the amount of power exported to the grid, Sofar call it "Reflux Power", it works by sampling the grid current and adjusting the inverter output so the grid power is zero.

 

Whilst the inverter can be set to export power ranging from zero (no export at all) to the full power available from the panels it does not have either remote control or a timer.

 

We want to only enable no-export when someone is likely to see the meter running backwards. Hence this little project.

 

Simply disconnecting the CT makes the inverter go to full power, so inserting a switch in the CT leads lets me control it without going outside.

 

Note:- Normally one would never leave the output of a CT open circuit as they can generate very large voltages, I checked the CT that came with the inverter and it only outputs 20V or so when open, not going to fry anyone.

 

Of course, being lazy and forgetful I wanted to automate the process. Our meter reader comes regularly on the 17th of the month, he has arrived a couple of times on the 16th and once on the 18th. So to avoid the possibility of him noticing the meter whizzing backwards I want to disable export (enable no-export) on the 16th to the 18th.

 

Needs a simple timer thinks I until I discover just how much a timer that does day/date control costs!

 

Enter the ESP8266 relay board. This chap:-

 

 

A couple of bucks from AliExpress. Combine it with a 5V power supply and a "manual" switch and we have an IoT (Internet of Things) device.

 

I was going to control it from the solar monitor, but encouraged by the success of the Wife Clock (Always Right) which uses an ESP8266 as an NTP (internet time) client and drives an LCD display I made it stand alone. 

 

The circuit:-

 

 

It looks like this, excuse the crappy soldering:-

 

 

 

This is the ESP8266 software - ESP8266_NTP_No_Export_Relay_1.0_Final.ino

 

Easy eh?

 

[Crossy]

Of course the best laid plans of mice ... (men do not enter into the equasion)

 

After a couple of weeks and the departure of the grandkids back to school and me back to full time at the office it has become apparent that we are generating "too much" solar (considerable reduction in A/C usage).

 

We won't go net-export but after 3 months of power usage in the order of 1,500 to 1,700 units the rapidly approaching bill was going to be 400 units. Thinking this level of change may attract unwanted attention I've permanently disabled export for the rest of the month so the solar is just covering the daytime load (about 13 units), this should give a more "believable" 800 units bill this month (a little less than the pre-lockdown level).

 

Madam has been encouraged to do the laundry etc. during the day when there's a surplus of solar.

 

I shall gradually wean the meter reader on to the lower bills.

 

Even if I was to never enable export again, payback time for the solar would still be under 4 years.

 

 

 

[carlyai]

Looks great Crossy. 

I think before you were pretty well using all you 45A single phase current. In the future do you plan not to be limited by the grid phase current available and just use the sun and batteries?

[Crossy]

3 minutes ago, carlyai said:

Looks great Crossy. 

I think before you were pretty well using all you 45A single phase current. In the future do you plan not to be limited by the grid phase current available and just use the sun and batteries?

 

Batteries are an option if we ever get stuck with a no-reverse meter, until then we'll just push excess into the grid. That bridge will get crossed when we come to it.

 

We do get near our 45A meter limit (50A incoming breaker) when we have visitors (our UK family like A/C when they visit) although the incomer has never opened on overload.

 

 

[Muhendis]

Innovation is clearly your forte. Well done.

Is it not possible to apply for a feed in tariff account? 

[johng]

2 hours ago, Crossy said:

This is the ESP8266 software

Its great you wrote your own code..but I,being very lazy ( not to mention  no coding skills)

would have used "Tasmota" it has a built in webserver,built in timers, can be easily integrated into a MQTT network, control with a phone app etc etc.

https://tasmota.github.io/docs/

[sometimewoodworker]

2 hours ago, Muhendis said:

Innovation is clearly your forte. Well done.

Is it not possible to apply for a feed in tariff account? 

To get a feed in tariff the paperwork is substantial, the installation has to use specific parts, the tariff is about 1.x baht per kw and the number accepted is small so making the pay back time about 3 times longer. This is why most installs run the meter back, if they don’t get caught. ???? 

[Crossy]

2 hours ago, Muhendis said:

Innovation is clearly your forte. Well done.

Is it not possible to apply for a feed in tariff account? 

 

It is ... 

 

But (there's always a "but").

 

In order to be eligible for the FIT (called "My Solar Roof" IIRC) you have to:-

• Use an approved inverter = $$$ PEA List here  https://www.pea.co.th/Portals/0/Document/vspp/PQM/PEA_Inverter_List_20200611.pdf
• Use an approved installer (no DIY) = more $$$
• Sign up for a significant period.
• Get paid about 2 Baht for each unit you export before paying 4.5 Baht for the same unit when you import it later.
• Get a absolute mound of paperwork approved by PEA.

Having spoken to PEA we decided to wing it, if we get caught out they will install a no reverse meter and we will have to look at whether it's worth going for a hybrid (batteries) solution.

 

EDIT And, it seems that you have to do the install and then get it approved, no idea what happens if it's not up to scratch.

 

EDIT2 At least there's a plus, the only Sofar inverter on the PEA list is a grid-tie hybrid.

 

[Metropolitian]

5 hours ago, Crossy said:

 

Always and Never wrong position? With regards to the  'Export Control'

 

Or it is my adaption of the language... ????

 

Export Control , 'Never' control the export,  CT need open.

Export Control,  'Always' control the export, CT need to be connected.

[Crossy]

5 minutes ago, Metropolitian said:

Export Control , 'Never' control the export,  CT need open.

Export Control,  'Always' control the export, CT need to be connected.

 

"Never" means "never export" (CT connected permanantly)

"Always" means "always export" (CT disconnected permanently)

 

Gotta just love the English language, it can mean whatever you want ????

 

[Metropolitian]

3 hours ago, johng said:

Its great you wrote your own code..but I,being very lazy ( not to mention  no coding skills)

would have used "Tasmota" it has a built in webserver,built in timers, can be easily integrated into a MQTT network, control with a phone app etc etc.

https://tasmota.github.io/docs/

Good suggestion, in fact I am using ESPeasy for that here. 

 

Running Home Assistant on the server which keeps history data, sends information to;

 

- a wireless LCD display by MQTT messaging.  (ESP Nodemcu boards)

- smaller sensors and relay switches which are programmed by code upload and works with URL commando's (ESP01s boards).

 

ESPHome is something worth to look at, integration with the automations but no fancy webserver so suitable for smaller ESP boards.

 

 

 

Tasmota:  https://tasmota.github.io/docs/

EspEasy:  https://www.letscontrolit.com/wiki/index.php/ESPEasy#Introduction

EspHome:  https://esphome.io/

Arduino ide: https://www.arduino.cc/en/Main/Software (Easy way to upload the code, comes with a load of libraries for the Arduino boards and displays.  For the ESP boards you need add libraries for it)

Aditional board libraries (ESP8266) for the Arduino ide : https://github.com/esp8266/Arduino

[sidgy]

So here is my effort. 

Have 3 x 360w mono panels (11,340bht) with Souer 1000w GTI (2900bht)

Had some steel already but had to buy two more lengths at 340 bht (780 bht), buy  4mmsq wire (247Bht) and MC4 connectors ( 2x 2into1 and  1pair) (290bht)

Have a couple more things to buy to tidy up ( i had conduit already but no clips etc) so total spend should be less than 16,000Bht and i have made the frames to take another 3 panels so shouldnt be as expensive for stage 2

So i eventually got it connected and producing around 15:30 on Tuesday but unfortunately it was mainly raining and cloudy until yesterday evening but by end of play yesterday i had produced 3.95kwh in 15 hours.

However today which was mainly quite sunny i managed 5kwh in 10 hours(i lost two hours this morning as waited until big lightning storm passed before switching on) 

 

 

[Crossy]

As one of those annoying people who likes to see what's going on at all times I picked up a couple of these baby (128x32) OLED displays. 

https://www.lazada.co.th//products/i1461942719-s3820172063.html 

They are very small but also very readable even the smallest of the text styles. There's also a 128x64 version in 0.9" which uses the same library and a 128x64 1.3" version which needs a different library. I have the necessary libraries if anyone wants them (saving a Google search).

 

 

Built a litte adaptor board that goes between the ESP-8266 and the relay board.

 

 

I've also modified the software to work with either the V4.0 relay board or the original V1.0 board and changed the manner in which one sets the dates for "no export".

 

ESP8266_NTP_No_Export_Relay_With_Display_2.0b.ino

 

The circuit, a handy by-product of using GPIO2 as SCL is that the on-board LED flashes at 1Hz when the display seconds field updates acting as a "heartbeat" indicator.

 

Note that the 128x64 versions have VCC and GND swapped vs the 128x32.

[Metropolitian]

3 hours ago, Crossy said:

As one of those annoying people who likes to see what's going on at all times I picked up a couple of these baby (128x32) OLED displays. 

 

Glad I'm not the only one 555 lost the counts of displays here

 

3 hours ago, Crossy said:

 

I've also modified the software to work with either the V4.0 relay board or the original V1.0 board and changed the manner in which one sets the dates for "no export".

 

The circuit, a handy by-product of using GPIO2 as SCL is that the on-board LED flashes at 1Hz when the display seconds field updates acting as a "heartbeat" indicator.

Is the clock right according your wife or NTP? ????

 

 

 

3 hours ago, Crossy said:

Note that the 128x64 versions have VCC and GND swapped vs the 128x32.

Seems random between displays, even for ones in the same range like the oleds..

 

 

This is a goose between the ducks ???? Although not I2C but uses serial data anyhow. Note the two GND's, only one is needed.

 

 

Still need to find out if I can use this with the ESP01

This display I ordered when I had the idea to once make a small Back To The Future time clocks.

 

 

 

 

 

[Crossy]

Yesterday 26/08/20 we broke the 30 units generated in one day barrier with 31.21 units from our 8 x 300W + 10 * 345W panels ???? 

 

We only used 6.8 units from the grid. Could be heading for an embarrassingly low bill if it doesn't rain. 

 

I've told Madam to do more ironing or something.

 

[BritManToo]

Just now, Crossy said:

Yesterday 26/08/20 we broke the 30 units generated in one day barrier with 31.21 units from our 8 x 300W + 10 * 345W panels ???? 

We only used 6.8 units from the grid. Could be heading for an embarrassingly low bill if it doesn't rain. 

I've told Madam to do more ironing or something.

You're lucky, it's been overcast/raining every day this month in Chiang Mai.

I'll be lucky to get 1/2 unit per day per panel.

[Crossy]

5 minutes ago, BritManToo said:

You're lucky, it's been overcast/raining every day this month in Chiang Mai.

I'll be lucky to get 1/2 unit per day per panel.

 

Yeah, it was an almost perfect day despite some high cloud, useful power from about 7AM to 5PM ????

 

July produced 530kWh and August to date 498kWh. Easily covers my beer bill with some change

 

 

 

[sidgy]

9 hours ago, Crossy said:

Yeah, it was an almost perfect day despite some high cloud, useful power from about 7AM to 5PM ????

 

July produced 530kWh and August to date 498kWh. Easily covers my beer bill with some change

Definately better weather this week.

Since i added the next 3 panels to give me 6 x 360w in total

week 1   51kwh     (Monday  to Sunday  )   

week 2   57kwh    (Monday  to Sunday  ) 

week 3   42kwh    (Monday to Thursday with 3 more days to go) 

 

As an aside

The second set of 3panels cosistently produces about 5-8 %  less than the first set of 3 each day. with exactly the same set up and equipment used. Not sure why as the difference between the two rows going into shade at post 18:00 is only about 10 mins and the power produced at this time is minimal,

Maybe i will try swapping the reading displays over to see if get the same % of difference to help guage how accurate they are

 

 

[Metropolitian]

 

Well... today was better then yesterday ????

 

This setup 3x300w panels ongrid.

[Crossy]

The "No Export Relay" now has a web interface so I can control it from anywhere should I get the urge and it stores the status in FLASH memory (the ESP8266 has no EEPROM) so it survives a reset / power failure.

 

The simplest of web interfaces but it does the job.

 

 

And the software if anyone is interested.ESP8266_SSD1306_NoExpRel_3.0a.ino

 

 

[scorecard]

Crossy,

 

Would it be true that since your venture the price of cells has gone down quite a bit?

 

And the quality of the panels slowly going up?

Edited September 23, 2020 by scorecard

[Crossy]

23 hours ago, scorecard said:

Would it be true that since your venture the price of sells has gone down quite a bit?

And the quality of the panels slowly going up?

 

Yup, 2,800 Baht for a 340W poly panel. 

https://www.lazada.co.th/products/340-w-genius-340-soler-panel-polycrytaline-340-kerry-i713768389-s1367528011.html

 

Power output per-panel is certainly increasing, "quality" from the low-cost Chinese factories remains to be seen.

 

We paid a bit more for our Trina panels, we also have 2 Lazada cheepies which are currently working just fine.

 

[Seeall]

On 9/1/2019 at 3:15 PM, johng said:

Imagine how much power would be produced if every roof top in Thailand was covered in solar panels..they would (probably) not have to import any electric from neighbouring countries and save billions on gas and oil.

 

also less tea money involved..