Diy mppt? - Page 11

Xringer · 01-23-11, 04:58 PM

"double the oscillation speed"? I don't know, but it should be an easy thing to test.
I think it's going to depend on your load. If it's a battery, what's it state of charge, etc.

I once ordered some of those cheap thin-film panels. But the dealer canceled my order
about a week later. When I called up to find out why, they said their web page was
malfunctioning and gave me a too low shipping cost...
Then, the man quoted me a shipping cost that was a lot more than the panels cost.
For the same price, I could get smaller, lighter and more powerful panels off Ebay.

It's possible to convert DC to a lower DC voltage using a Buck Converter.
Buck converter - Wikipedia, the free encyclopedia

It's not easy. One of the main problems I see with using a DIY Buck regulator,
if it fails, your load will be hit with very high voltage.. Not good in some cases..

fabieville · 01-25-11, 12:45 AM

There are some LEDs (light emitting diodes) that produces about 1.5VDC when you expose them to sunlight. I know the current rating of them is very small. I have never tested the current rating of them by shorting the leads i only tested how much voltage i get from them when they are exposed to light. I am assuming that the current rating is in the micro amp reading.
I am wondering if there are any available with current rating in the milli-amp/amp stage when you shorts it?
Because i am thinking that you could wire some in series to get say 18VDC then connect lots of the series strings in parallel to increase the current rating and then you would have a nice little panel at a really affordable price.
What is your comment on this?

Xringer · 01-25-11, 08:38 AM

Sorry, but I had never even heard of an LED used as a PV device, until I saw the Red Rock tracker board.

This page, Electronic Projects might have some info about the type of LEDs that are being used.

Because of their very small light capture area, the amount of sunlight
that can fall on the silicon material, is VERY small..

And, a very small amount of sunlight means a very small amount of power.
It would likely take thousands of LEDs to make one watt of power.

Insolation - Wikipedia, the free encyclopedia

Solar Calculator: DNI Solar Energy Calculator, Insolation Calculator

In this area, we get an Average of 3.7 kWh/m^2*day.

So, if we are getting 3.7 kWh of sun light each day falling on one square meter,
How much would we get falling on one square millimeter?
3.7 miliwatts?

fabieville · 02-28-11, 11:44 PM

I notice something about the mini max. Whenever I set the target setpoint closer to the battery voltage for eg. 13.8V the battery receives more charge than when I set a higher target setpoint for eg. 16V.

I did a test just to confirm it using 2 same testers that are calibrated to have the same reading and when I was doing the test the solar PV was facing directly in the sun and it was quite a sunny day. I was getting approx. 20 VOC from the PV. There weren't any clouds blocking the panel at anytime cause as I said the day was very sunny.

One tester was connected to the battery while the other was connected to the input of the mini max to view the target setpoint voltage.

When I adjust the setpoint to 16V I notice that the battery voltage read 12.80V and then when I decrease the setpoint to 13.8V I notice the battery voltage went up a little to about 12.91V.

So I am guessing that probably when the setpoint is much lower it causes the Cap to charge up much faster reaching the setpoint much quicker and then discharging in the battery at a much faster rate than if it had to charge up to 16V.

This is not really a problem for me I just want to know what is your comment on my analysis. If this is so I am really glad as with the lower setpoint it would work in both cloudy and sunny peroids.
__________________

Xringer · 03-01-11, 07:58 AM

Using a battery as a load to run accurate tests is very difficult.
The exact stage of charge (SOC) is going to determine your results.

You must look at your real-world usage. Is the system working better?
If you measure and log the power being used, and compare it to before,
you should be able to tell if it's working better.

fabieville · 03-04-11, 04:40 AM

If I use a mppt charge controller such as the TriStar-60 MPPT Solar CONTROLLER that have a max. input of 150VDC, will it allow me to use the high voltage solar panels (100 VOC) that are rated for roughly about 1 amp to charge my 12V battery?

And will it operate in the form of stepping down the panel's voltage while increasing the current output at the same time that is going into the battery so I end up getting close to the panel's total wattage? Am I correct?

Reason why I ask this is because the high voltage panels are sold at a far cheaper price than the regular ones. Just as an example, In Jamaica where I live a regular 100 Watt panel (20VOC, 17V, 5.8amp) cost about JA$32,000 while the same 100 watt but high voltage one(100V @ 1amp thin film) cost about JA$8,000.

But the thing is that you could not use the high voltage panel to charge a 12v battery as the VOC is too high but I was thinking that if I run it through a mppt controller that can manage that high input voltage then I could get it to efficiently charge a 12v battery and I would get close to the same 100watt. Which would work out cheaper economically buying the higher voltage panels than buying the regular ones. Hence upgrading would be much cheaper when you want to add more panels.

I would love to hear your comments on this.

Xringer · 03-04-11, 08:40 AM

You should use the Morningstar String Calculator at,
Morningstar String Calculator

You might have to input the thin-film panel specs. The only thin-film that
I'm familiar with, is 60w and around 100w open.

Those 100w /cheaper thin-film panels are larger and heavier than normal PVs.
The may cost a bit more to ship and mount.

I ordered some thin-film once, but canceled the order when they increased the shipping charges.
Shipping costs per-panel was more than the cost of the panel..

Those MPPT controllers cost more than the PWM chargers (I have the TS-45 PWM),
but MPPT will work better during cloudy conditions, and during dawn & dusk.

I've been told, they are worth the extra money.
IMHO, that might depend on your local conditions.
If you get a lot bright sunshine for a lot of hours,
MPPT might not be much better than PWM.

When it's sunny (and cool) and my TS-45 is charging my 48v bank at
300w, I can turn on 200w of load and see my panels are putting out
their full rating of 500w. Charging the bank and running my PCs..

The PV array seems provide good output at around 70vdc.

My point is, during sunny conditions, both chargers will charge
your bank at about the same rate.

fabieville · 03-04-11, 08:45 AM

I dont have to buy the panels online they are sold in my country.

Xringer · 03-04-11, 09:24 AM

Ben got some of those 60w thin-films...

http://ecorenovator.org/forum/solar-...ing-solar.html

Xringer · 05-24-11, 10:18 AM

Saw some news about DC mppt..

Solaredge Launches New Top Efficiency Power Optimizers and PV Safety Innovations at Intersolar Europe | SolarEdge Technologies

YouTube - ‪SolarEdge: maximum PV energy at a lower cost - Part 1/3‬&rlm;

It's an idea that I've been thinking about using, since I have a lot of trees around.
Maybe it's possible to DIY some little boards for each panel, that would
do MPPT on it's panel and then discharge it's stored power at the MPP voltage of a fixed value (per the PV spec).

This should keep any panel (in a parallel config) from dragging the others down with low voltage. (due to shading).
A shaded panel would not even be connected, until it had charged up it's storage capacitor to spec voltage.

It has been my experience that a shaded panel that's not loaded down,
(open) will still have a pretty good output Voltage (not much amps),
but the voltage will normally exceed the spec MPPV..

So, the function of the DIY circuits would be to isolate any panel, until it
could contribute it's stored (capacitor) power at higher voltage (MPPV).

The paralleled panels would be pulsing off and on, delivering power pulses to the load.
If any panel was seeing full sun, it would not be isolated, unless the load
pulled down the buss voltage. When that occurred, the DC MPPT board
would disconnect and wait until it had full spec voltage and pulse it to the buss.

Kinda like a poorman's Enphase (but in DC)..

Seems like a good idea, at this time..

01-23-11, 04:58 PM	#101
Xringer Lex Parsimoniae Join Date: Feb 2009 Location: Woburn, MA Posts: 4,918 Thanks: 114 Thanked 250 Times in 230 Posts	"double the oscillation speed"? I don't know, but it should be an easy thing to test. I think it's going to depend on your load. If it's a battery, what's it state of charge, etc. I once ordered some of those cheap thin-film panels. But the dealer canceled my order about a week later. When I called up to find out why, they said their web page was malfunctioning and gave me a too low shipping cost... Then, the man quoted me a shipping cost that was a lot more than the panels cost. For the same price, I could get smaller, lighter and more powerful panels off Ebay. It's possible to convert DC to a lower DC voltage using a Buck Converter. Buck converter - Wikipedia, the free encyclopedia It's not easy. One of the main problems I see with using a DIY Buck regulator, if it fails, your load will be hit with very high voltage.. Not good in some cases..

01-25-11, 12:45 AM	#102
fabieville Helper EcoRenovator Join Date: Dec 2010 Location: Jamaica Posts: 59 Thanks: 0 Thanked 0 Times in 0 Posts	There are some LEDs (light emitting diodes) that produces about 1.5VDC when you expose them to sunlight. I know the current rating of them is very small. I have never tested the current rating of them by shorting the leads i only tested how much voltage i get from them when they are exposed to light. I am assuming that the current rating is in the micro amp reading. I am wondering if there are any available with current rating in the milli-amp/amp stage when you shorts it? Because i am thinking that you could wire some in series to get say 18VDC then connect lots of the series strings in parallel to increase the current rating and then you would have a nice little panel at a really affordable price. What is your comment on this?

01-25-11, 08:38 AM	#103
Xringer Lex Parsimoniae Join Date: Feb 2009 Location: Woburn, MA Posts: 4,918 Thanks: 114 Thanked 250 Times in 230 Posts	Sorry, but I had never even heard of an LED used as a PV device, until I saw the Red Rock tracker board. This page, Electronic Projects might have some info about the type of LEDs that are being used. Because of their very small light capture area, the amount of sunlight that can fall on the silicon material, is VERY small.. And, a very small amount of sunlight means a very small amount of power. It would likely take thousands of LEDs to make one watt of power. Insolation - Wikipedia, the free encyclopedia Solar Calculator: DNI Solar Energy Calculator, Insolation Calculator In this area, we get an Average of 3.7 kWh/m^2*day. So, if we are getting 3.7 kWh of sun light each day falling on one square meter, How much would we get falling on one square millimeter? 3.7 miliwatts?

02-28-11, 11:44 PM	#104
fabieville Helper EcoRenovator Join Date: Dec 2010 Location: Jamaica Posts: 59 Thanks: 0 Thanked 0 Times in 0 Posts	I notice something about the mini max. Whenever I set the target setpoint closer to the battery voltage for eg. 13.8V the battery receives more charge than when I set a higher target setpoint for eg. 16V. I did a test just to confirm it using 2 same testers that are calibrated to have the same reading and when I was doing the test the solar PV was facing directly in the sun and it was quite a sunny day. I was getting approx. 20 VOC from the PV. There weren't any clouds blocking the panel at anytime cause as I said the day was very sunny. One tester was connected to the battery while the other was connected to the input of the mini max to view the target setpoint voltage. When I adjust the setpoint to 16V I notice that the battery voltage read 12.80V and then when I decrease the setpoint to 13.8V I notice the battery voltage went up a little to about 12.91V. So I am guessing that probably when the setpoint is much lower it causes the Cap to charge up much faster reaching the setpoint much quicker and then discharging in the battery at a much faster rate than if it had to charge up to 16V. This is not really a problem for me I just want to know what is your comment on my analysis. If this is so I am really glad as with the lower setpoint it would work in both cloudy and sunny peroids. __________________

03-01-11, 07:58 AM	#105
Xringer Lex Parsimoniae Join Date: Feb 2009 Location: Woburn, MA Posts: 4,918 Thanks: 114 Thanked 250 Times in 230 Posts	Using a battery as a load to run accurate tests is very difficult. The exact stage of charge (SOC) is going to determine your results. You must look at your real-world usage. Is the system working better? If you measure and log the power being used, and compare it to before, you should be able to tell if it's working better.

03-04-11, 04:40 AM	#106
fabieville Helper EcoRenovator Join Date: Dec 2010 Location: Jamaica Posts: 59 Thanks: 0 Thanked 0 Times in 0 Posts	If I use a mppt charge controller such as the TriStar-60 MPPT Solar CONTROLLER that have a max. input of 150VDC, will it allow me to use the high voltage solar panels (100 VOC) that are rated for roughly about 1 amp to charge my 12V battery? And will it operate in the form of stepping down the panel's voltage while increasing the current output at the same time that is going into the battery so I end up getting close to the panel's total wattage? Am I correct? Reason why I ask this is because the high voltage panels are sold at a far cheaper price than the regular ones. Just as an example, In Jamaica where I live a regular 100 Watt panel (20VOC, 17V, 5.8amp) cost about JA$32,000 while the same 100 watt but high voltage one(100V @ 1amp thin film) cost about JA$8,000. But the thing is that you could not use the high voltage panel to charge a 12v battery as the VOC is too high but I was thinking that if I run it through a mppt controller that can manage that high input voltage then I could get it to efficiently charge a 12v battery and I would get close to the same 100watt. Which would work out cheaper economically buying the higher voltage panels than buying the regular ones. Hence upgrading would be much cheaper when you want to add more panels. I would love to hear your comments on this.

03-04-11, 08:40 AM	#107
Xringer Lex Parsimoniae Join Date: Feb 2009 Location: Woburn, MA Posts: 4,918 Thanks: 114 Thanked 250 Times in 230 Posts	You should use the Morningstar String Calculator at, Morningstar String Calculator You might have to input the thin-film panel specs. The only thin-film that I'm familiar with, is 60w and around 100w open. Those 100w /cheaper thin-film panels are larger and heavier than normal PVs. The may cost a bit more to ship and mount. I ordered some thin-film once, but canceled the order when they increased the shipping charges. Shipping costs per-panel was more than the cost of the panel.. Those MPPT controllers cost more than the PWM chargers (I have the TS-45 PWM), but MPPT will work better during cloudy conditions, and during dawn & dusk. I've been told, they are worth the extra money. IMHO, that might depend on your local conditions. If you get a lot bright sunshine for a lot of hours, MPPT might not be much better than PWM. When it's sunny (and cool) and my TS-45 is charging my 48v bank at 300w, I can turn on 200w of load and see my panels are putting out their full rating of 500w. Charging the bank and running my PCs.. The PV array seems provide good output at around 70vdc. My point is, during sunny conditions, both chargers will charge your bank at about the same rate.

03-04-11, 08:45 AM	#108
fabieville Helper EcoRenovator Join Date: Dec 2010 Location: Jamaica Posts: 59 Thanks: 0 Thanked 0 Times in 0 Posts	I dont have to buy the panels online they are sold in my country.

03-04-11, 09:24 AM	#109
Xringer Lex Parsimoniae Join Date: Feb 2009 Location: Woburn, MA Posts: 4,918 Thanks: 114 Thanked 250 Times in 230 Posts	Ben got some of those 60w thin-films... http://ecorenovator.org/forum/solar-...ing-solar.html

05-24-11, 10:18 AM	#110
Xringer Lex Parsimoniae Join Date: Feb 2009 Location: Woburn, MA Posts: 4,918 Thanks: 114 Thanked 250 Times in 230 Posts	Saw some news about DC mppt.. Solaredge Launches New Top Efficiency Power Optimizers and PV Safety Innovations at Intersolar Europe \| SolarEdge Technologies YouTube - ‪SolarEdge: maximum PV energy at a lower cost - Part 1/3‬&rlm; It's an idea that I've been thinking about using, since I have a lot of trees around. Maybe it's possible to DIY some little boards for each panel, that would do MPPT on it's panel and then discharge it's stored power at the MPP voltage of a fixed value (per the PV spec). This should keep any panel (in a parallel config) from dragging the others down with low voltage. (due to shading). A shaded panel would not even be connected, until it had charged up it's storage capacitor to spec voltage. It has been my experience that a shaded panel that's not loaded down, (open) will still have a pretty good output Voltage (not much amps), but the voltage will normally exceed the spec MPPV.. So, the function of the DIY circuits would be to isolate any panel, until it could contribute it's stored (capacitor) power at higher voltage (MPPV). The paralleled panels would be pulsing off and on, delivering power pulses to the load. If any panel was seeing full sun, it would not be isolated, unless the load pulled down the buss voltage. When that occurred, the DC MPPT board would disconnect and wait until it had full spec voltage and pulse it to the buss. Kinda like a poorman's Enphase (but in DC).. Seems like a good idea, at this time..