How about a solar car port on a budget?

[Crossy]

9 hours ago, tifino said:

not sure @Crossyfrom the photo, as to how much Fall there is to your roof? 

, but I am assuming the Panels are situated  more towards the Higher side? 

 - had that thought arise, due to the amount of recent rains, that the channels may have nearly filled?

-  and thought of just how close is the inundation allowed to be with the Panels? 

 

Fall on the roof is 300mm over the 6m length (I've never seen standing water on the roof), the panels are about 100mm above the bottom of the channels.

 

9 hours ago, Muhendis said:

Those inverters don't appear to have any finned heat sinks. Would it be possible to get some and fit them. If it can be done it would be better than fitting a punkah walla. All moving parts fail sooner or later.

 

There are rather minimal looking fins on the sides, at the rated full-power efficiency of 95% the inverter would be dissipating 20W or so.

 

 

Also, closer perusal of the somewhat minimal manual does show the inverters hanging vertically under the panels in the airflow. Both inverters are now back in the vertical orientation.

[Muhendis]

The output of solar panels can be a bit misleading. There is a label on the back which tells the max open circuit voltage and maximum current and also the loaded values including maximum power. Just a reminder that these figures are under ideal conditions which is with the sunshine perpendicular to the panel and the ambient temperature at 25 degrees C. As the ambient temperature rises so the output from the panel goes down and as the sun drifts across the sky the panel output varies. But then I expect you guys are aware of this already.

just so you know, I have a 7.2kW solar panel array which charges, via MPPT charge controllers, my 750ah battery bank and supplies 48v to an 8kW single phase off grid inverter. My hobby and house are quite power hungry.

[Muhendis]

1 hour ago, Crossy said:

Also, closer perusal of the somewhat minimal manual does show the inverters hanging vertically under the panels in the airflow. Both inverters are now back in the vertical orientation.

It would be a good idea to turn those inverters 90 degrees so that the "fins" are vertical. Air flow through them will be significantly better. 

[Crossy]

8 minutes ago, Muhendis said:

It would be a good idea to turn those inverters 90 degrees so that the "fins" are vertical. Air flow through them will be significantly better. 

 

Yeah, I was looking at that as part of moving them into the really shady area.

[RideJocky]

And how close are they (the inverters) to the roof panels?

Dropping them down while still in the shade might help.


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[Crossy]

7 minutes ago, RideJocky said:

And how close are they (the inverters) to the roof panels?
Dropping them down while still in the shade might help.

 

About 100mm clear air above.

 

All great stuff chaps, keep it coming.

[alan grice]

Interesting read , more a project for younger folk to me as i cant see much saving as units here are cheap and our bills not much. Ive had solar on a Motorhome Coach it ran air con in Texas heat all night but installation was costly and one thing no ones mentioned is bird droppings , and dust/ sand sticking after rain ,or cleaning them often to ensure efficiency.They were a novelty at first , but here im a bit doubtful re maintenance.Perhaps if i was younger .!.


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[Muhendis]

21 minutes ago, alan grice said:

Interesting read , more a project for younger folk to me as i cant see much saving as units here are cheap and our bills not much. Ive had solar on a Motorhome Coach it ran air con in Texas heat all night but installation was costly and one thing no ones mentioned is bird droppings , and dust/ sand sticking after rain ,or cleaning them often to ensure efficiency.They were a novelty at first , but here im a bit doubtful re maintenance.Perhaps if i was younger .!.


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As you say Alan. Payback can be quite a few years even with grid tie and a good feed in tariff from PEA. It depends on how many years you are planning to live.........????

If your missus is young and agile, you could send her up onto the roof once a week with a mop and a bucket of water. She'll soon have the panels like new. 

[bankruatsteve]

And here there are several times during the year we get little bugs that land on everything light in color and die making a real sticky mess.  Not too hard to clean but looks terrible until that's done.

[sfokevin]

14 hours ago, Crossy said:

They are supposed to be convection cooled, I am trying to avoid using some of my valuable solar to move air.

Could you add a addition heat sink with some the thermal glue...

 

https://www.lazada.co.th/catalog/?q=Heat+sink&_keyori=ss&from=input&spm=a2o4m.home.search.go.1125719cAGMNrP

 

Also have you analyzed your daily energy usage profile to see if you energy needs match up with the solar generation?... I assume your meter does not run backwards?... Or does it?

[Crossy]

14 minutes ago, sfokevin said:

Could you add a addition heat sink with some the thermal glue...

 

Indeed I could, but I shouldn't have to if these things are properly designed.

 

Conventional mechanical meters as supplied by PEA do indeed run backwards just fine although with only 4 panels we've not gone into export as yet.

 

If ours doesn't read backwards on export I'll have to re-think the way forwards, sadly this is going to involve batteries and $$$ ????

 

 

[tifino]

1 hour ago, Crossy said:

 

About 100mm clear air above.

 

All great stuff chaps, keep it coming.

plus... situating the inverters directly under roof, that is covered by the panels as well! 

 - gives a doubleup fringe benefit insulating layer, via the 2 stages of shading... 

 

orientation of a heatsink might not in itself add/subtract any measureable benefit regarding heat conduction through the material of the heatsink... 

(the fins themselves would only be a matter of inches in length? and BTU transfer would be more noticeable, relatively, between metal/air interface (convection);

rather than 'within' the relatively smaller bulk of the metal to just itself (conduction) .

 

 

[Crossy]

A snapshot of the inverter status just now. As yet the inverters are in full shade under the panels and the roof.

 

 

Things are a lot warmer than I would like at only 50% rated output.

 

From the numbers, efficiency is a reasonable 93% but we still have to get rid of 20-30W of heat.

 

 

[sometimewoodworker]

10 minutes ago, Crossy said:

A snapshot of the inverter status just now. As yet the inverters are in full shade under the panels and the roof.

 

 

Things are a lot warmer than i would like at only 50% rated output.

 

 

When I was recycling some old PCs in Japan (taking them apart so I didn't have to pay the 2,000 baht to dispose of them ) I took out the heat sinks for parts, that could be a source of cheap ones.

[Muhendis]

35 minutes ago, Crossy said:

Indeed I could, but I shouldn't have to if these things are properly designed

In my opinion, commercial products made in China are rarely environmentally tested. China is not a hot country like Thailand so if it works ok there the rest would be down to component level tolerance and thermal consideration. Sometimes the Chinese can be flexible with their specs.

[Crossy]

4 minutes ago, Muhendis said:

Sometimes the Chinese can be flexible with their specs.

 

Indeed they can, I will talk to the manufacturer next week, their support chap has been very responsive thus far.

 

Currently pushing 800W from the two 600W inverters and 4 x 300W panels, inverters showing 63C and 64C.

[tjo o tjim]

2 hours ago, Crossy said:

If ours doesn't read backwards on export I'll have to re-think the way forwards, sadly this is going to involve batteries and $$$ ????

fwiw, your load profile seems to show your instantaneous power going close to negative, not the 15-minute average. That might make a small battery work ok in balancing your output with load. 

 

The double micro-inverters seem like an uphill battle on heat dissipation. Do you know your thermal coefficient for the panels?  Rule of thumb is to size the panels 10% larger than the inverter, but that doesn’t help the economic calculation. 

[Crossy]

2 hours ago, tjo o tjim said:

Do you know your thermal coefficient for the panels?

 

 

Panel datasheet https://static.trinasolar.com/sites/default/files/PS-M-0328 Datasheet_Tallmax_2018_B_0.pdf

 

 

[BritManToo]

4 hours ago, Crossy said:

Currently pushing 800W from the two 600W inverters and 4 x 300W panels, inverters showing 63C and 64C.

It's 2:30pm and sunny, getting 190W from my 330w panel.

[Crossy]

We (just) broke the 1kW barrier at 12.30 (times on the chart are China Standard Time), it's starting to cloud over now ready for the evening flash-and-bang.

 

[RideJocky]

I need to get decent roof access to our shophouse...

 

I have 64m^2 and the in-laws have 192 I can use...

 

 

[Crossy]

From Kaideng support regarding inverter temperature.

 

Quote

Good day，

 

It is normal for the surface temperature to exceed 60°. Our maximum surface temperature can reach 70°. If it exceeds 75°, it will have a protection mechanism. This is called over-temperature protection.

 

If you can install a cooling fan for it, this is a very good idea, because we are constantly improving the cooling system of the inverter. Because it needs to be waterproof, it is impossible to install a cooling fan, and it can only rely on the heat dissipation of the body. Features.

 

We are constantly improving. If you have good suggestions, you can tell me that we will accept it. Thank you.

 

Best regards

Anson Guo

 

I hooked up a 100mm 12V fan as a test measure and it reduced the maximum temperature to below 60C. I'll do the job properly at the weekend.

 

I've also got some aluminium heatsink extrusions on order to test as additional passive cooling.

 

[Muhendis]

I guess the inverters must be using the outer case to dissipate heat from the internal components. I think the temperatures mentioned are a bit high for what is supposed to be functional in an ambient of 40 or so. Also the support guy says that the cut out temperature is 70 but didn't you say earlier that the inverter was cutting out at 60? At those sort of temperatures you need to be wary of what you touch. The comments about "waterproof enclosure" make sense so with this in mind, the manufacturer should have increased the surface area of the enclosure for operation in ambient above (say) 25C by fitting heat sink cooling fins. An external fan would be a bit risky if the units are mounted in the open. 

Another thought occurs to me with regards to protection from the elements. You aught to consider installing a surge arrestor because a local indirect lightning strike can generate a big EMP which will destroy your hard work and hard earned expenditure on the project. They are available from Lazada and are not expensive. https://www.lazada.co.th/-i2047347-s2372828.html?urlFlag=true&mp=1 It was only a year ago that I had this unfortunate experience which destroyed two out of three hybrid inverter/charge controllers. These had internal line protection which simply wasn't up to the job. 

[Crossy]

Surge suppression already installed ????

 

The shutdowns are odd as I've had both inverters at 65C without them cutting out and when they do shut off the status still reports "normal", other times they've gone off at 59C. But since bodging on the fans (OK only 1 day) they didn't shut down once.

 

The "back" of the unit (opposite the indicator light) seems to be the main heatsink area so I'm going to bang a chunk of heatsink extrusion on that side using self-adhesive heat-conducting tape.

 

To be honest, if it works with a couple of cheap 12V fans and a solar panel to drive them then the job's a good un.

 

[sometimewoodworker]

56 minutes ago, Crossy said:

From Kaideng support regarding inverter temperature.

 

 

I hooked up a 100mm 12V fan as a test measure and it reduced the maximum temperature to below 60C. I'll do the job properly at the weekend.

 

I've also got some aluminium heatsink extrusions on order to test as additional passive cooling.

 

The extra heatsinks will certainly help. I have a Mac Mini server that likes to run hot but with this (center punch for scale) the fan seldom spins up more than a silent 1800 rpm with the CPUs at 62~68C (maximum temperature for them is 105C and max fan speed is 5,500 rpm

[sometimewoodworker]

11 minutes ago, Muhendis said:

the manufacturer should have increased the surface area of the enclosure for operation in ambient above (say) 25C by fitting heat sink cooling fins.

they are on the two narrow sides, if you go back to the pictures.

[Crossy]

2 minutes ago, sometimewoodworker said:

they are on the two narrow sides, if you go back to the pictures.

 

and they are stupidly small ????

 

[BritManToo]

27 minutes ago, Crossy said:

The "back" of the unit (opposite the indicator light) seems to be the main heatsink area so I'm going to bang a chunk of heatsink extrusion on that side using self-adhesive heat-conducting tape.

Thermal tape isn't very effective.

You should use CPU thermal paste.

[Crossy]

Just now, BritManToo said:

Thermal tape isn't very effective.

You should use CPU thermal paste.

 

I know, but there's no real way to attach anything without taking the beast apart which I want to avoid at present (warranty and all that jazz).

[BritManToo]

10 minutes ago, Crossy said:

I know, but there's no real way to attach anything without taking the beast apart which I want to avoid at present (warranty and all that jazz).

My 600W Suoer unit has much more heatsink on all four sides and twin internal fans, the fans start coming on when it's producing over 200W. When I first saw the WTC design, I did wonder how it could dissipate heat so much more efficiently than mine and without any fans.

 

Clearly the answer is, yours just stops working when it gets hot.