How about a solar car port on a budget?

[Muhendis]

9 minutes ago, RideJocky said:

Wet constantly in the sun won’t algae grow?

Wet-dry-wet-dry in the sun won’t bad water-spots develop?




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No. Algae grows in standing water.

Not understanding your water spots.

[Crossy]

1 hour ago, Muhendis said:

No. Algae grows in standing water.

 

indeed, but there's some yukky green "weed" that makes its home in moving thin films of water, 'orrible stuff it is too.

 

[007 RED]

We've just had a fairly heavy downpour which has washed a load of coffee dust/granules off the roof and dumped it onto the glazed tiles at the side of the house.  The photo below shows the crux of the problem that I face from the nearby coffee factory.

The above example may be slightly exaggerated in so far that it's the run-off from the house roof, but will give you some idea why I have a concern regarding keeping a solar panel system clean.

 

I've found a piece of glass (which I've cleaned) and placed at an angle approximately representing the slope of carport roof, in the open.  I'll monitor the glass surface daily to see how much detritus accumulates on it over the next week or so and I'll also see what affect a gentle water spray has on cleaning it off.

Edited September 21, 2019 by 007 RED

[Muhendis]

37 minutes ago, Crossy said:

 

indeed, but there's some yukky green "weed" that makes its home in moving thin films of water, 'orrible stuff it is too.

 

Most unpleasant watery thingies die in direct sun so an occasional dry hour might fix that.

By the way did you know that leaving a bottle of water out in the sun will kill all the bacteria?

That stuff on the tiles looks like it might be good for the garden. Keep quite about it or the factory may make a charge............

[sometimewoodworker]

4 hours ago, 007 RED said:

Could you please expand on your advice.... what adverse affect will hard water have on the panels?

Have you looked at the thread about cleaning the glass on a shower? Have you looked inside a kettle or hot water pipe in a hard water area? 

 

 

[Muhendis]

4 hours ago, RideJocky said:

Wet-dry-wet-dry in the sun won’t bad water-spots develop?

Just had a shower and now I think I know what you mean by water spots. Those would be caused by the left over drops of water on the glass after the cooling water has stopped for the night. Any minerals/dirt/coffee in the water will be left where the left-over drop was after its water has evaporated. I'll have to dig out my old Heath Robinson design notes to see if there is an automatic panel wiping blade to use after the water has stopped for the day. In northern Europe where panels are at an inclination of about 52 degrees that is not a problem but here we are merely 17 degrees nominal so gravity is not so helpful. Aside from that the spots are unlikely to have any noticeable affect on the operation of the panels. Don't forget the cooling effect of the water will improve the efficiency of the panel by as much as 20% worst case (I think). On reflection, I think I will scrap the "automatic panel wiping blade" idea on the basis of diminishing returns.

[Muhendis]

I had a look for cleaning systems and this is the first one I came across. Not brilliant but with a bit of time and effort it could be improved I think. Adding a drop of washing up liquid would help but not too much otherwise you can imagine what will happen.

https://www.youtube.com/watch?v=1X6KCHdRn2U

Another good reason to cool/clean the panels is that life expectancy is significantly increased by as much as 30%.

Edited September 21, 2019 by Muhendis
new information

[RideJocky]

I had a look for cleaning systems and this is the first one I came across. Not brilliant but with a bit of time and effort it could be improved I think. Adding a drop of washing up liquid would help but not too much otherwise you can imagine what will happen.

Another good reason to cool/clean the panels is that life expectancy is significantly increased by as much as 30%.

If you’re recirculating the water, will it not get hot pretty quick?

The water-spots are calcium and other minerals and would accumulate over time.

Moving/lifting that much water is a good bit of work.

I would think “raining” on the panels would be more effective than just running over them.

In the clip he never showed how the panels looked after they were dry...

[Muhendis]

10 hours ago, RideJocky said:

 

If you’re recirculating the water, will it not get hot pretty quick?

The water-spots are calcium and other minerals and would accumulate over time.

Moving/lifting that much water is a good bit of work.

I would think “raining” on the panels would be more effective than just running over them.

In the clip he never showed how the panels looked after they were dry...

 

Yes your quite right, the water would get hot however as the panels cool down the amount of heat transferred from the panels diminishes so the temperature of the water in the storage tank will not be so great as one would imagine. Also if the storage tank is big enough then the water will take ages to get hot. As you say, raining on the panels is better than the video especially if the rain effect was from spray nozzles which can be individually adjusted to dispense the right volume of water. This would imply a pressure pump rather than a flow pump. The advantage of using a pressure pump is that the nozzles would all receive about the same pressure to deliver water evenly across the panels.

https://www.duan-daw.com/product/1396/50gpd-ปั๊มไดอะแฟรม-diaphragm-ปั๊มอัดผลิตหม้อแปลงไฟ-dew-อิตาลี This pump is just for illustration purposes.

A more complex arrangement could be to have a closed loop electronic control system which would monitor the panel temperature and switch the pump on at a higher temperature (say 40) then switch it off at a lower temperature (say 22). 

[RideJocky]

Yes your quite right, the water would get hot however as the panels cool down the amount of heat transferred from the panels diminishes so the temperature of the water in the storage tank will not be so great as one would imagine. Also if the storage tank is big enough then the water will take ages to get hot. As you say, raining on the panels is better than the video especially if the rain effect was from spray nozzles which can be individually adjusted to dispense the right volume of water. This would imply a pressure pump rather than a flow pump. The advantage of using a pressure pump is that the nozzles would all receive about the same pressure to deliver water evenly across the panels.
https://www.duan-daw.com/product/1396/50gpd-ปั๊มไดอะแฟรม-diaphragm-ปั๊มอัดผลิตหม้อแปลงไฟ-dew-อิตาลี This pump is just for illustration purposes.
A more complex arrangement could be to have a closed loop electronic control system which would monitor the panel temperature and switch the pump on at a higher temperature (say 40) then switch it off at a lower temperature (say 22). 

Unless you are using some kind of chiller, the water is never going to get down to 22. It’s raining at 9:30 in the morning and it’s 26 out. How would you get the water temp below ambient?

I think it safe to assume the water will be turning brown even if we’re filtering out the coffee dust.

I think if we’re near a water source such that we could just pump and dump a cooling system that cleans the panels might work, but moving that much water is a lot of work.

I’m still thinking once a week with a hose-pipe and a long handled sprinkler and we’re done...

[Muhendis]

2 hours ago, RideJocky said:

 

Unless you are using some kind of chiller, the water is never going to get down to 22. It’s raining at 9:30 in the morning and it’s 26 out. How would you get the water temp below ambient?

I think it safe to assume the water will be turning brown even if we’re filtering out the coffee dust.

I think if we’re near a water source such that we could just pump and dump a cooling system that cleans the panels might work, but moving that much water is a lot of work.

I’m still thinking once a week with a hose-pipe and a long handled sprinkler and we’re done...


 

 

I don't think a chiller would be economically viable for Crossy and his budget solar but if the water were to come from a few metres down in a surface water well then that would be pretty cool. Mine's about 20 degrees. The water quality shows as 174 mho conductance on a TDS meter which is very clean. This would be the same as your pump and dump idea except that I would dump the water back into the well via a sediment filter.

[007 RED]

18 hours ago, sometimewoodworker said:

Have you looked at the thread about cleaning the glass on a shower? Have you looked inside a kettle or hot water pipe in a hard water area? 

 

 

Many thanks... The penny eventually dropped. 

 

We do have hard water and certainly experience the small shower nozzles getting blocked with calcium every so often.  Because we have a 'wet room' (no glass shower screens) I've not encountered the staining on the glass.

 

Certainly another possible problem to think about.  As you said originally "the cure will be worse than the disease".

[007 RED]

4 hours ago, Muhendis said:

Yes your quite right, the water would get hot however as the panels cool down the amount of heat transferred from the panels diminishes so the temperature of the water in the storage tank will not be so great as one would imagine. Also if the storage tank is big enough then the water will take ages to get hot. As you say, raining on the panels is better than the video especially if the rain effect was from spray nozzles which can be individually adjusted to dispense the right volume of water. This would imply a pressure pump rather than a flow pump. The advantage of using a pressure pump is that the nozzles would all receive about the same pressure to deliver water evenly across the panels.

https://www.duan-daw.com/product/1396/50gpd-ปั๊มไดอะแฟรม-diaphragm-ปั๊มอัดผลิตหม้อแปลงไฟ-dew-อิตาลี This pump is just for illustration purposes.

A more complex arrangement could be to have a closed loop electronic control system which would monitor the panel temperature and switch the pump on at a higher temperature (say 40) then switch it off at a lower temperature (say 22). 

The concept which you describe above would be OK under normal circumstances.  Unfortunately in my case I would be initially collecting water from the carport roof which would contain coffee dust/granules.  I suspect that the larger granules would sink to the bottom of the holding tank and the finer particles may well be dissolved into the water making it discoloured and possibly eventually sticky.  This contaminated water would then be sprayed back onto the panels and I suspect will cause a discoloured film or patches to form on the panels as they dry.

 

I already have a 1k litre water tank plus pump under the carport. The tank is fed from the water main.  We use it for washing the car and watering vulnerable plants during the summer.  It would be easy enough to rig up a spray system (better than the Heath Robinson one shown on the Indian video).  Bearing in mind another members comments about hard water (which we have), some form of calcium filter may be needed to avoid stains on the panels when they dry.

 

As mentioned in a previous post, I've placed a piece of glass in the open, inclined at approximately the same angle as the carport roof, in order to get a better feel for how much muck gets deposited over a period of time, and if spraying the glass with tap water cleans the dust/granules off and will the untreated water leave any noticeable stains on the glass.

[Muhendis]

1 hour ago, 007 RED said:

some form of calcium filter may be needed to avoid stains on the panels when they dry.

For the first six months of this year I was entirely reliant on bore hole water which has a conductivity of 2850 mho due to TDS. The major mineral is calcium and I have been searching all over the place for a means of filtering it out. If you find anything which will do the job apart from Reverse Osmosis, Resin beads or Capacitive Deionisation please let me know I would be really grateful. 

[Crossy]

OK, the inverters have moved into a totally shaded and well ventilated area.

 

One unit has fans, the other is the "control" unmodified unit.

 

 

Fans are currently mains powered via a modified photo-switch (comes on when it's light).

 

 

Althought it's pretty overcast and each inverter is only pushing out about 150W the unit with fans is a full 6^oC cooler than the unmodified unit (49^oC as opposed to 55^oC).

 

We shall see how well it works when the sun comes out.

 

As noted earlier, I have some heatsink extrusions on order, passive cooling would be preferable.

 

 

[Muhendis]

16 minutes ago, Crossy said:

OK, the inverters have moved into a totally shaded and well ventilated area.

 

One unit has fans, the other is the "control" unmodified unit.

 

 

Fans are currently mains powered via a modified photo-switch (comes on when it's light).

 

 

Althought it's pretty overcast and each inverter is only pushing out about 150W the unit with fans is a full 6^oC cooler than the unmodified unit (49^oC as opposed to 55^oC).

 

We shall see how well it works when the sun comes out.

 

As noted earlier, I have some heatsink extrusions on order, passive cooling would be preferable.

 

 

Progress is looking good. That looks like 11% improvement but still finger burningly hot. 

[RideJocky]

Progress is looking good. That looks like 11% improvement but still finger burningly hot. 

Only for sissy fingers....

[tjo o tjim]

Sounds ultimately like an inverter efficiency problem.  I don’t know how Enphase does it, but their inverters seem to have a plastic housing now.

[Crossy]

9 hours ago, tjo o tjim said:

Sounds ultimately like an inverter efficiency problem.  I don’t know how Enphase does it, but their inverters seem to have a plastic housing now.

 

Interesting. Enphase publish an efficiency of 97.5% so at 400W they have to get rid of 10W worth of heat. That's a lot to dissipate for a plastic housing, I expect they run pretty darn warm.

 

The WVC inverters publish an efficiency of 95% so at 400W they need to get rid of 20W which really shouldn't be an issue for a well designed metallic housing.

 

If I can trust the figures coming from the inverters I'm seeing an efficiency of 92.5% @ 300W so that's 22.5W of heat. Really shouldn't be beyond passive cooling, I await my extra heatsinks with bated breath.

[carlyai]

Most (unfaned) electronic things seem to run really hot these days, spose it's the greater specs. of the components. Will see if you can dissapate that heat without a fan. Or maybe you're increasing the heatsink area for the fan?

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[Crossy]

18 minutes ago, carlyai said:

Most (unfaned) electronic things seem to run really hot these days, spose it's the greater specs. of the components. Will see if you can dissapate that heat without a fan. Or maybe you're increasing the heatsink area for the fan?

 

You're probably right, my Android TV box runs too hot to touch and just seems to keep on going.

 

I'm from the old school where hot things were made of glass with a vacuum inside and "solid state" electronics ran cool. In reality they'll likely be just fine but running cooler either with the fans or extra heatsinks cannot hurt the reliability.

 

[RideJocky]

 
You're probably right, my Android TV box runs too hot to touch and just seems to keep on going.
 
I'm from the old school where hot things were made of glass with a vacuum inside and "solid state" electronics ran cool. In reality they'll likely be just fine but running cooler either with the fans or extra heatsinks cannot hurt the reliability.
 

If they ran hot without shutting down they’d be fine, yes?

I’m amazed at how hot my phone gets sometimes...

[Peterw42]

18 minutes ago, Crossy said:

 

You're probably right, my Android TV box runs too hot to touch and just seems to keep on going.

 

I'm from the old school where hot things were made of glass with a vacuum inside and "solid state" electronics ran cool. In reality they'll likely be just fine but running cooler either with the fans or extra heatsinks cannot hurt the reliability.

 

I think the reliability comes from the fact that nowadays components are already running at the top end of their specifications. If a component operates between 0-100 degrees, Years ago you designed a circuit where a component ran at 50 degrees with plenty of headroom for heating cooling etc, nowadays in order to achieve smaller, more functionality etc, its jammed into a slim laptop etc and running at 98 degrees. Any change in airflow, breakdown of heatsink etc and its fried.

 

[RideJocky]

I think the reliability comes from the fact that nowadays components are already running at the top end of their specifications. If a component operates between 0-100 degrees, Years ago you designed a circuit where a component ran at 50 degrees with plenty of headroom for heating cooling etc, nowadays in order to achieve smaller, more functionality etc, its jammed into a slim laptop etc and running at 98 degrees. Any change in airflow, breakdown of heatsink etc and its fried.
 

Laptop, another thing that gets amazingly hot and keeps working.

I

[tjo o tjim]

Did some digging on enphase; their inverters are rated for 85C component temperature with a 20C rise above ambient. Must be using the conductors for heat dissipation. 

[carlyai]

Did some digging on enphase; their inverters are rated for 85C component temperature with a 20C rise above ambient. Must be using the conductors for heat dissipation. 

OR streatching the spec. truth. Seems like you have to de-rate specs. now days.
My Chinese genset gets nowhere near the load current specs. 3BB 100/100 gets close if you test nearly touching the router.

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[carlyai]

Just as a heat sink comparison, here's my 300/300 W amp I'm still building.

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[Muhendis]

Gadget manufacturers are like politicians. They will only tell you about the bits that are favourable to them.

We must try to work out what things they omit from the spec. sheet. For example. Does the inverter work ok with a non linear load? If that question is not answered in the spec. then it probably doesn't.

[alan grice]

Like My CD System, now only the Speakers are worth keeping.!.


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[emptypockets]

On 9/24/2019 at 7:55 AM, Peterw42 said:

I think the reliability comes from the fact that nowadays components are already running at the top end of their specifications. If a component operates between 0-100 degrees, Years ago you designed a circuit where a component ran at 50 degrees with plenty of headroom for heating cooling etc, nowadays in order to achieve smaller, more functionality etc, its jammed into a slim laptop etc and running at 98 degrees. Any change in airflow, breakdown of heatsink etc and its fried.

 

Won't be long before you will need a plumber to install electronics.