How about a solar car port on a budget?

[Crossy]

32 minutes ago, Muhendis said:

Looking at your picture again, are those soot stains I see? What happened?

 

Bangkok's crappy pm2.5 levels happened, it's just dust deposited from the fan airflow.

 

It does show how the air flows out of the fans mind.

 

[Crossy]

12 hours ago, Muhendis said:

You may need to place those step down modules (buck regulators) in front of the fan. They get hot also. If they didn't they wouldn't be cheap.

 

Yeah, they do get a bit warm, not hot enough to worry about, we shall see. Maybe small metal boxes could be on the cards.

 

The data puts the efficiency of the adjustable version at about 90%, so with 6W of load (0.5A @ 12V) I reckon they're dissipating about 1W but I've not done any measurements.

[Crossy]

On 12/28/2019 at 3:32 PM, Crossy said:

A quick update and bump.

 

In order to run the fans only during the day I got a bunch of these 

https://www.aliexpress.com/item/4000084041472.html 

 

At a whole $0.42 US (plus I paid the extra for tracked shipping) it's hardly worth building something.

 

Max input voltage 40V (the LM2596S is actually good to 45V), set for 12V output. Take the input from one of the panels (1 unit per inverter). Small plastic box 20 Baht from NPE.

 

Fans start when it's barely light.

 

Welllll, the best laid plans of mice ...

 

After installing the converters for the fans the two 600W inverters seemed to decide not to start automagically in the morning, the 1200W unit behaved as expected. A prod or two from the "startup" button on the app and things sprang into life.

 

So, yesterday I removed the converter from one of the 600W units. Lo and behold that unit started just fine today, the other required a prod to wake it up.

 

I can't imagine it's a loading issue (the panels are getting to >40V) so possibly the squeeker is upsetting the MPPT circuits in the inverter.

 

So we're back to Plan-B (always have a Plan-B) of powering the fans from the mains via a photo switch modified to be "off" at night.

 

 

[Muhendis]

I had a very similar problem with my small 12v hot water circulation pump (solar hot water). Although the small solar panel seemed big enough to easily power the pump, there was more oomph required to start it than was sometimes available and if it didn't start when the sun rose in the morning then it would just sit there smiling knowingly to itself all day. The worst time is when things were a bit cloudy. I did a fix for this which is really quite simple. I used a comparator to detect when the solar panel voltage was at 15v or so and at that voltage it would switch power to the pump. After that all problems went away and the water got nicely hot for my evening shower. 

[Crossy]

Yeah, it could well be fixable if I stop the converter from starting until the panel reaches 24V or so (maybe 30V).

 

There's even an application in the data sheet.

 

 

It just depends on my level of "be-bothered-ness" and what zeners I've got in the bits box.

 

[Muhendis]

I think that is the TI data sheet you pasted. The editor needs shooting because the hysteresis circuit and the negative output circuits are the same. I think it's a good job I can work independently of these application notes. I had little choice about the  level of "be botherdness" as 'er indoors spotted the problem before I did.

[Crossy]

 

It is indeed the TI sheet, happens to be the first that popped up on Google. 

 

The app notes are a good starting point, but they are just what they say they are "notes" (and they are indeed often <deleted>), around which an engineer can build his design.

 

But why re-invent the wheel? The circuit I cut looks like it should work, pull the on/off pin low to start the converter when the input voltage gets to V_zener + V_be (or about 1V). It's probably not how I would have done it starting from scratch, but my thought process is now polluted (as well as being dulled by more years than I care to remember since I actually did any serious design).

 

As far as be-botheredness is concerned, I have a viable solution (the modified photo switch) which I know will work, it's just not particularly elegant, can I be bothered to build something different, (particularly as I'll need one per inverter) who knows for now.

 

And yes, I agree, when Madam is affected be-botheredness gets raised by a power of 10 to the detriment of anything that I may want to do ????

 

 

 

[Muhendis]

I like your idea of the opto switch although I think it may have a few problems when we get a bit cloudy and it can't decide what to do. 

[Crossy]

If it's cloudy it doesn't really matter as we won't be generating much and the inverters won't need the fans ????

 

The units I have (which can be dismantled to modify, just move the output wire to the NC relay contact) have a fair amount of hysteresis and time delay anyway, that said the one which controls our patio lights does flicker a couple of times as it gets dark. Cheap Chinese, built to a price, dare I say it "junk", but it (mostly) does the job required of it and when it does go "pop" cheap enough to bin and put in a new one.

 

 

[Crossy]

Optical switch installed along with a 24V 5A PC power supply that was "in stock". Still using the converters to drive the 12V fans.

 

I will have this as my "permanent" solution until a better idea pops up.

 

Maybe run the fans via a remote link from my energy monitor so they only run when the inverters are working hard and getting hot, add in an ambient temperature sensor so they don't run on cool days - Must stop thinking

 

Each pair of fans (one inverter) draws about 400mA at 12V = about 5W. So when we have our full complement of 9 inverters that's 45W just for the fans. Running for 12 hours that's about 0.5 units per day just for the fans! Our full complement of 18 panels will make about 18 units per day, that's nearly 3% of our generation running the fans.

 

A 100W panel costs about 2k Baht from Amorn, that would run all the fans at zero energy cost and repay it's own cost in 3 years ..... 

 

Really, really must stop thinking now ????

 

Nearly time for the cricket to start = Time for a cold one ????

 

 

 

 

[Metropolitian]

Two 20 watt panels here next to the 300 watt panels.

To run the fans for the inverter, and charging a 7aH battery.

Fans are small, taken from PC power supplies.

Not a dyson but does move the airflow at the fins.

No sun equals no fan turning, but the same goes for the inverter ????

Diode blocks the fan eating from the battery, which is just for backup and led light and for sensors in the future.

This project never stops ????

[Crossy]

Just a quick update. No significant modifications, just let it run. 

 

I am working on a revised monitoring system using a couple of cheap "smartish" power meters which have RS-485 and another Arduino, definitely work-in-progress.

 

Meanwhile we made 224.92kWh from 8 panels in January, about 900 Baht off the power bill ????

 

[ExpatOilWorker]

11 hours ago, Crossy said:

Just a quick update. No significant modifications, just let it run. 

 

I am working on a revised monitoring system using a couple of cheap "smartish" power meters which have RS-485 and another Arduino, definitely work-in-progress.

 

Meanwhile we made 224.92kWh from 8 panels in January, about 900 Baht off the power bill ????

 

What is the total cost, including all the modifications, paid labor cost, but not your own time?

[Crossy]

9 hours ago, ExpatOilWorker said:

What is the total cost, including all the modifications, paid labor cost, but not your own time?

 

For the 8 panels, inverters, "misc" plus the labour about 50k Baht all in (not including the car port itself).

 

So it should have paid for itself after about 4 years.

[ExpatOilWorker]

1 hour ago, Crossy said:

 

For the 8 panels, inverters, "misc" plus the labour about 50k Baht all in (not including the car port itself).

 

So it should have paid for itself after about 4 years.

Probably closer to 5 years with less power production during the rainy season.

What is your nominal or name plate power rating?

[Crossy]

Yeah, it will be interesting to see how it goes in the wet.

 

We have 8 * 300W panels with 2 * 600W and 1 * 1200W micro-inverters so rated power of  2400W,

 

Max generated power is in the region of 1.7kW (had to hunt by hand, the Kaidaeng software isn't big on analysis facilities).

[ExpatOilWorker]

12 minutes ago, Crossy said:

Yeah, it will be interesting to see how it goes in the wet.

 

We have 8 * 300W panels with 2 * 600W and 1 * 1200W micro-inverters so rated power of  2400W,

 

Max generated power is in the region of 1.7kW (had to hunt by hand, the Kaidaeng software isn't big on analysis facilities).

Interesting, so on average you got 3 hours of nominal power production per day in January. 

[Crossy]

3 minutes ago, ExpatOilWorker said:

Interesting, so on average you got 3 hours of nominal power production per day in January. 

 

Pretty much.

 

The system actually starts making power at about 7AM and makes its last watt at 5.30PM.

Peak output is, predictably, around noon.

 

 

[Muhendis]

Wet weather will cool the panels so any light on the panels will produce more power than expected and the rains rarely last more than an hour per day. I usually have similar concerns for my system but after 6 years or so, my batteries are always full by lunch time or soon after and usage during charging generally includes running an assortment of woodworking machines etc. Having said that I am a bit nervous at the moment because a new road is under construction to my house and my temporary/emergency/backup supply from PEA (which I haven't used for years) is temporarily taken down.

[ArranP]

Heres what I installed, figured out the wiring from examining photos and itineraries of combiner boxes for sale on aliexpress.  Totally off-grid no connectiont to PEA.

 

 

BATTERY - Prismatic - 48v200ah BMS ( 100A ) included. - $1860 

https://www.alibaba.com/…/Customized-Solar-System-Battery-1…

I Will buy anohter later and put in parallel

 

INVERTER - 1x EASUN POWER 5000W Solar Inverter 5Kva 450Vdc PV 80A MPPT Parallel Inverter 48V 230V 80A Battery Charger - $780 includes import tax and door to door

https://www.aliexpress.com/item/32899640591.html

Can link 9 together in parallel to make 45000W

 

PANEL - 10x Bluesun mono solar panel 96 cells 450w - $1350 ( excludes shipping & import tax )

https://www.alibaba.com/…/Bluesun-mono-solar-panel-96-cells…

Next time Its cheaper to buy the panels in Thailand e.g. 330w poly approx 3,900 each. Amorn / Global House.

 

 

Edited February 26, 2020 by ArranP

[Muhendis]

17 hours ago, ArranP said:

Heres what I installed, figured out the wiring from examining photos and itineraries of combiner boxes for sale on aliexpress.  Totally off-grid no connectiont to PEA.

 

 

BATTERY - Prismatic - 48v200ah BMS ( 100A ) included. - $1860 

https://www.alibaba.com/…/Customized-Solar-System-Battery-1…

I Will buy anohter later and put in parallel

 

INVERTER - 1x EASUN POWER 5000W Solar Inverter 5Kva 450Vdc PV 80A MPPT Parallel Inverter 48V 230V 80A Battery Charger - $780 includes import tax and door to door

https://www.aliexpress.com/item/32899640591.html

Can link 9 together in parallel to make 45000W

 

PANEL - 10x Bluesun mono solar panel 96 cells 450w - $1350 ( excludes shipping & import tax )

https://www.alibaba.com/…/Bluesun-mono-solar-panel-96-cells…

Next time Its cheaper to buy the panels in Thailand e.g. 330w poly approx 3,900 each. Amorn / Global House.

 

 

You didn't include your combiner box in your list of bits. Hopefully you have one.

[Crossy]

17 hours ago, ArranP said:

 

BATTERY - Prismatic - 48v200ah BMS ( 100A ) included. - $1860 

https://www.alibaba.com/…/Customized-Solar-System-Battery-1…

I Will buy anohter later and put in parallel

 

INVERTER - 1x EASUN POWER 5000W Solar Inverter 5Kva 450Vdc PV 80A MPPT Parallel Inverter 48V 230V 80A Battery Charger - $780 includes import tax and door to door

https://www.aliexpress.com/item/32899640591.html

Can link 9 together in parallel to make 45000W

 

 

What duty rate did you pay on your battery and inverter?

 

[Muhendis]

18 hours ago, ArranP said:

figured out the wiring from examining photos and itineraries of combiner boxes for sale on aliexpress. 

If it retrospectively helps at all, here's my circuit:-

solar wireing diagram.pdf

[Crossy]

5 minutes ago, Muhendis said:

If it retrospectively helps at all, here's my circuit:-

 

Other people's installations are always good to see.

 

How are you controlling the ATS to go on mains if necessary?

 

 

 

[Muhendis]

14 minutes ago, Crossy said:

 

Other people's installations are always good to see.

 

How are you controlling the ATS to go on mains if necessary?

 

 

 

It's an auto priority thing with solar on the number one side. The auto/manual switch is currently set to manual since the new road construction to my house necessitated the removal of my temporary PEA connection.

edit.

I just had a thought. The inverter has a hysteresis reaction for the battery voltage so there should not be any battle between the two supplies at the ATS switch.

Edited February 27, 2020 by Muhendis

[Crossy]

2 minutes ago, Muhendis said:

It's an auto priority thing with solar on the number one side. The auto/manual switch is currently set to manual since the new road construction to my house necessitated the removal of my temporary PEA connection.

 

So (when you actually have mains) if flips to mains power if the solar runs out of juice?

 

Sounds good to me.

[Muhendis]

2 minutes ago, Crossy said:

 

So (when you actually have mains) if flips to mains power if the solar runs out of juice?

 

Sounds good to me.

Yes but take care with lightning protection on the incoming. A local strike can be quite spectacular in the ATS ????

[Metropolitian]

This is the ongrid setup here. 2K inverter (currently 800watt).

 

In the plastic box with analog DC volt meter inside an DC breaker and Surge Arrester.

 

Middle CU still unfinshed, has to replace the old wiring first.

 

Another CU for the domestic DC is still in the making. With battery banks for low voltage devices, charged by one panel on day and the grid on nights.

 

[ArranP]

On 2/27/2020 at 7:21 AM, Muhendis said:

You didn't include your combiner box in your list of bits. Hopefully you have one.

 

Didn't buy a combiner box...  worked out the components in side it instead and mounted them on the gypsum board next to the inverter.

• lightning arestor
• 2 pole fuse
• pv array string fuse 
• ground pole

 

 

Just to note, if using a transformerless inverter both the positive and negative leads from the each pv string need to be fused, otherwise if the inverter has a transformer only the positive needs to be fused.

 

example of a combiner box available on aliexpress or alibaba this is for an inverter with transformer as just the positive leads are fused.

 

 

 

 

 

Edited February 28, 2020 by ArranP

[ArranP]

On 2/27/2020 at 7:44 AM, Crossy said:

 

What duty rate did you pay on your battery and inverter?

 

 

battery - nothing additional to pay, it was all included in the price, the seller completed the import slip etc.

 

inverter - about 17%

 

panels - needed shiping, couldn't come by air, when shipping, there is additional courier fees import handling etc, ends up cheaper to buy here Amorn or somewhere like that at 3,900 baht per 330w panel

 

Edited February 28, 2020 by ArranP
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