How about a solar car port on a budget?

[Muhendis]

On 7/8/2021 at 8:35 AM, Crossy said:

100kg of farang can hang on there

Only if found guilty.

 

Looking good

[Crossy]

I got some used CALB (allegedly, they're not marked) golf-cart LiFePO4 cells for experimental purposes for 1,500 Baht each for 200Ah, 48V pack cost 25,500 Baht including a 100A BMS.

 

https://www.lazada.co.th/products/i2527489409-s8982895965.html

 

Tested one at 20A down to 2.5V and got 168Ah. That's potentially the equivalent of around 300Ah of lead-acid!

 

They must be pretty worn, but treated gently and for experimental purposes they can't be bad.

[gamb00ler]

I have been following this thread for quite a while and I have enjoyed it immensely.

 

Perhaps I missed it, but @Crossy, have you calculated the payback period taking into consideration the low rate PEA is willing to pay for the excess generation that you feed back into the grid?

 

The calculation is probably a snap for a meticulous data collector???? such as yourself.???? 

[Crossy]

15 minutes ago, gamb00ler said:

I have been following this thread for quite a while and I have enjoyed it immensely.

 

Perhaps I missed it, but @Crossy, have you calculated the payback period taking into consideration the low rate PEA is willing to pay for the excess generation that you feed back into the grid?

 

The calculation is probably a snap for a meticulous data collector???? such as yourself.???? 

 

We are doing the "unofficial" net metering (spinning the conventional meter backwards whilst exporting) with mitigation in place to prevent the meter reader actually seeing it going backwards. Others have run into problems and had no-reverse meters fitted. So the actual calculation is easy using all the solar output at 4.5 Baht per unit as the financial value. Payback on the current system is around 3 years.

 

I've not calculated payback based upon the rather feeble feed-in tariff (2.1 Baht per unit IIRC). PEA only pay you for what you actually export (which varies with the weather as the available solar gets used for local consumption) so the sums are rather harder. I have all the data so I might sit down and do it if I get the urge.

 

On a good day we might export and re-import (at night) 12 units of a total solar generation of 30 units, on a less good day we may not export at all and generate maybe 14 units from the solar.

 

We never get to actual net export as our daily energy consumption from solar and grid is between 40 and 60 units dependant upon how many visitors we have using A/C.

[Crossy]

2 hours ago, Crossy said:

We are doing the "unofficial" net metering (spinning the conventional meter backwards whilst exporting) with mitigation in place to prevent the meter reader actually seeing it going backwards.

 

Of course the batteries and hybrid inverter are there for testing for when we end up with an electronic or no-reverse meter which I'm sure will happen one day (hopefully not too soon of course).  

[Crossy]

Sunday.

 

Steelwork completed, tiles going on.

 

 

Getting the first row of tiles to fit with the existing roof under the solar was a bit of a wrestle as we couldn't reach the screws to loosen. A bit of farang muscle applied underneath got them in eventually.

 

 

 

Total materials cost just under 24,000 Baht.

Labour (family) about 5k plus food and beer.

 

 

[johng]

6 minutes ago, Crossy said:

Total materials cost just under 24,000 Baht.

Don't forget you'll need another car to put under the new car port  ????

[Crossy]

15 minutes ago, johng said:

Don't forget you'll need another car to put under the new car port  ????

 

Obviously, it's main purpose is to support more solar, but I'm sure Madam has plans.

 

I think it will be more entertainment space once the covid crisis is over, she told me yesterday it needs lights (solar powered of course).

[ExpatOilWorker]

Crossy, since your solar plant have been running for a while now, do you have good data for how much energy you get out of your system on a cloudy overcast day?

Maybe not your absolute worse day, but an average low number, preferably in Kwh/m2 per day. 

 

The upper limit is a bit easier to estimate.  Do you get somewhere around 0.8 kWh/m2 on a clear sunny day?

 

Not to hijack this thread, just need low data to design a small solar/battery system for my UV light and pump nuclear plant. Maybe include a few LED lights for emergency use. I will skip the whole AC part and stay on 24 V DC.

[Crossy]

17 minutes ago, ExpatOilWorker said:

The upper limit is a bit easier to estimate.  Do you get somewhere around 0.8 kWh/m2 on a clear sunny day?

 

The best day last year was about 0.91kWh/m² so 0.8kWh/m² probably isn't a mile off as an average "good" day, really nasty days drop to 0.25kWh/m².

 

The last week of "mostly cloudy" days have averaged around 0.65kWh/m².

 

I have the production data back to March last year in a 50MB .csv (it's every 60 seconds) but it doesn't have weather in there, if you fancy crunching some numbers.

[Crossy]

Whilst we are talking about production, here are July's numbers.

 

Note the outlier on the 3rd wasn't a super good day, the extra came from a pre-charged battery pack on the hybrid.

 

[BritManToo]

11 minutes ago, Crossy said:

Whilst we are talking about production, here are July's numbers.

My worst month this year (114 units from 5 panels) ....... but luckily it didn't matter, because my COVID discount was from my best month this year. Final bill = 400bht

[ExpatOilWorker]

8 hours ago, Crossy said:

 

The best day last year was about 0.91kWh/m² so 0.8kWh/m² probably isn't a mile off as an average "good" day, really nasty days drop to 0.25kWh/m².

 

The last week of "mostly cloudy" days have averaged around 0.65kWh/m².

 

I have the production data back to March last year in a 50MB .csv (it's every 60 seconds) but it doesn't have weather in there, if you fancy crunching some numbers.

That the spread between good and bad sun days is only 0.25-0.9 kWh/m2 is encouraging. 

A small 5 m2 system could run 100 W and just let the BMS cut power during the night for cloudy days, that way the system is not significantly "wastful" during sunny days.

 

Thanks for the data mining offer, but I also need time to enjoy the view.

 

[Crossy]

14 minutes ago, ExpatOilWorker said:

but I also need time to enjoy the view.

 

Nice! Very nice ???? 

 

[sidgy]

So in the UK at the moment but got wife to send me the figures from our panels.

one bank of 3 over 13 months produced 1557kw/h second bank of 3 over 12 months produced 1247kw/h for total of 2804units. 

At 4.5 baht per unit over 12000baht saved so far so well on course to pay for itself within the 3year target

[Crossy]

Here we go with August production, not wonderful but still better than last year.

 

[Crossy]

So today we went shopping. I have purchased 12 x 340W Jinyuan poly panels @ 2,890 Baht a pop, from Global House I'm in instant-gratification mode.

 

EDIT I ordered and paid online via the Global website for pickup from our local store, the store called when they were ready for collection (slightly over the promised 30 minutes, but no problem) so minimal interaction with crowds all very easy and professional.

 

So assuming the weather is OK tomorrow the supports will go up along with the panels if time permits.

 

This will bring us to just over 10kWp which is probably going to be our final configuration, there is room for a further 6 panels but they would be quite heavily shaded by the house in the afternoon.

 

Once these panels are up the configuration will look something like this:-

 

 

More news as it happens!

 

[Crossy]

For completeness I've pulled this from another thread, this is what we currently have in the battery box.

 

Since we are "experimental" (and not millionaires) I got the used golf-cart batteries from lifepo4shop 

https://www.lazada.co.th/products/calb-lifepo4-32v-200ah-4-12v-i2523760591-s8967280783.html

 

I've seen these advertised as "new" on AliExpress but CALB stopped using that case style some years back. I've also got a "100Ah" pack which I was given by a mate who was rather miffed to find they measured at 50Ah, so yes finding a good seller isn't always easy!

 

They're certainly well used, testing at about 80% of new capacity but at 1,600 Baht a pop what's not to like. We will see how they go life wise. They're coupled with a Daly 16S 100A Smart BMS

https://www.lazada.co.th/products/i2480878972-s8740847689.html

 

We also have a "flying capacitor" active balancer which can shift 5A between any pair of cells if they go off balance. With used and probably mis-matched cells I consider this an essential item. It works very well, this morning the cells are within 12mV according to the BMS.

https://www.lazada.co.th//products/i2299959424-s7751185517.html

 

[sezze]

12 hours ago, Crossy said:

So today we went shopping. I have purchased 12 x 340W Jinyuan poly panels @ 2,890 Baht a pop, from Global House I'm in instant-gratification mode.

 

EDIT I ordered and paid online via the Global website for pickup from our local store, the store called when they were ready for collection (slightly over the promised 30 minutes, but no problem) so minimal interaction with crowds all very easy and professional.

 

So assuming the weather is OK tomorrow the supports will go up along with the panels if time permits.

 

This will bring us to just over 10kWp which is probably going to be our final configuration, there is room for a further 6 panels but they would be quite heavily shaded by the house in the afternoon.

 

Once these panels are up the configuration will look something like this:-

 

 

More news as it happens!

 

How good do they work together , the grid tie unit and the hybrid ? Does the hybrid charge the battery 1st ( is that a standard way hybrids work , when charging the battery before putting out 220V ) ?

[Crossy]

1 hour ago, sezze said:

How good do they work together , the grid tie unit and the hybrid ? Does the hybrid charge the battery 1st ( is that a standard way hybrids work , when charging the battery before putting out 220V ) ?

 

I did a thread about the various inverter types https://aseannow.com/topic/1228023-whats-all-this-on-grid-off-grid-hybrid-stuff-all-about-solar-systems-demystified/

 

Basically a grid-tie hybrid aims to keep the grid consumption at zero, excess solar will charge the batteries, if solar is insufficient the batteries will discharge to top up, once the batteries reach a set limit energy is imported from the grid, if the batteries are full excess solar is exported to the grid (configurable for zero export).

 

The inverters themselves play pretty well together without any actual communications between them, the hybrid does its thing whilst pretty much ignoring the pure grid-tie.

 

One trap I did fall into was assuming (I know, I know) that the two Sofar inverters would talk to the same internet logging software so I could see everything at a glance. 

 

I was wrong! 

 

The grid-tie came from a seller in China and turns out to be a mainland-only unit (not for export) and talks to one site, the hybrid came from a seller in Thailand and is the Aussie export model, it talks to a different (rather better) site. They also have different Wi-Fi dongles and won't talk to the other type. Grrr.

 

It's possible that the Aussie firmware would run on the grid-tie unit (if I could get it) but Sofar Support whilst generally helpful and communicative won't say if it will and wouldn't let me have a copy anyway. Obviously I also worry about bricking the unit (I do have the Chinese firmware so should be able to go back but ...).

 

In reality my DIY monitor does everything I need and when I get the odd moment I'll do something with Node-Red to integrate both inverters and the BMS's (they all have RS-485), but that's a future project.

 

All good fun.

 

[sezze]

Very nice to know , since it would mean a good grid tie unit can work together prob with a standard off grid unit

Your Sofar units are both good quality but 40+k for the hybrid is a lot of cash . Knowing you can have off grid units mppt 5kW at around 15000 and a grid tied and around 10000 . Idk why the decent on grid hybrids are sooo expensive since the technology needed is very low to make them hybrid , but im not a constructor ( which prob is the reason , since they like to jack up the price of the intelligent ones ) . Cut out the mppt track , build in a low to high voltage transformer and a chip which controls both flows and you are done . All buy them is not expensive , get them in 1 box and suddenly it gets very expensive .

[Crossy]

The weather is being kind at present, but there's a promise of flash, bang and dampness later ???? 

 

Solar mounting rails go up, we're using the same method as for the first batch.

 

 

Maintenance walkway in place for ease of cleaning with the hose and our telescopic pool brush.

 

 

It's right about now that one realises that solar panels actually aren't all a standard size

 

 

 

 

 

[Daffy D]

30 minutes ago, Crossy said:

It's right about now that one realises that solar panels actually aren't all a standard size

TIT  

[Crossy]

End of a long hot day, not connected yet, I'll do that in the cool of the morning. Just getting pizza (beer is in stock of course) for everybody!!

 

 

[Crossy]

For anyone who's interested the "budget" has expanded somewhat, total spend is now 220,499 Baht (not including the actual structure).

 

No indication of payback at present coz the new panels haven't actually generated a watt.

 

[Crossy]

OK, panels wired up and generating, all we need now is a decent sunny day ???? 

[Crossy]

Well yesterday was "cloudy" according to the forecast but actually turned out pretty sunny.

 

We generated 41.8kWh from the solar and used 2.4kWh from the grid. We exported and then re-imported 13.4kWh giving me an idea of how much more storage we will need if/when we get an electronic meter installed.

 

The cool weather has meant that our total daily consumption is down somewhat due to less A/C usage. I'll be monitoring closely we don't want a suspiciously low bill just yet. Our average daily grid consumption from our last bill was 25kWh.

 

Maybe I need to start a campaign of leaving lights on or taking longer hot showers (grand-daughter won't need any encouraging there), my turning the lights off campaign has been a bit too successful

[carlyai]

Have you still got the genset weaved into the schematic?

[Crossy]

2 minutes ago, carlyai said:

Have you still got the genset weaved into the schematic?

 

Yup, not using the EPS output of the hybrid as yet. So if the juice goes out we run the genset.

 

I need to do some magic with the wiring as the EPS can only do 3kW.

 

[carlyai]

24 minutes ago, Crossy said:

 

Yup, not using the EPS output of the hybrid as yet. So if the juice goes out we run the genset.

 

I need to do some magic with the wiring as the EPS can only do 3kW.

 

So you've still got grid, solar, batteries and genset all automatic?