Want to run a 12v fish tank pump of solar.

[Helimadness]

Isc is the max current output under Standard Test Conditions (STC) without a load on it. You want to use that x 1.25 to determine the size charge controller you need. You can go bigger, but not smaller.

The number of hours you use to calculate output are number that equals the output of STC, not the number of hours the sun is up. As you know, the sun is much brighter at noon as it is at sunrise, so not all hours are equal. In Qingdoa, that ranges from 4.23 - 5.55 sun hours. It takes local weather conditions into account, but that's a good question about pollution, I wonder if it accounts for that as well. http://solarelectricityhandbook.com/...rradiance.html

Thanks for the replies all very helpful.
Received the panels last night and hooked up quickly. As expected inside only produced about 3v. Got to 7v with my phone LED flash pointed at them
This morning on my way out the door at 730 am I checked and got about 11v but not enough to kick the motor in. That is just after sun up but.
Thanks for that link on the sun hours / day. Very interesting and helpful.

The pollution is monitored fairly closely here these days. http://aqicn.org/city/qingdao/
Today is good. Over the weekend PM2.5 was in the 300's Certainly cuts a lot of sun out. Will see if I can measure max performance on a clear day and crap day.

Assume voltage and current performance output is fairly directly related to sun input? Or is it better to measure the performance by just voltage or current output? Or can you just measure voltage output and the current will be relative to that? Assume as they are rated at 6v (I have 2 in series so 12v) there listed current output is at 6v. What would be the max voltage I would expect to see in absolute best case?

Cheers

[Amy@altE]

I must have missed that info. Thanks for finding it.

You are correct the OP can use even the small 6A CC for his pump since it is only rated 350ma.

I just wanted to make it clear to other readers that a CC will normally not control the operation of the "load" if the battery voltage gets low. That is because most "loads" are connected directly to the battery weather they are AC inverters or DC powered equipment.

Exactly, the Load Control option on some charge controllers will turn off only what small DC loads are connected to the charge controller, that then passes the DC voltage through to the connected load. Its intended use is to have something like a light connected to it, so if you accidentally leave it on, it will turn it off to save the battery. It will not turn it back on until the battery is charged up enough. In this example, since his load is a non-critical pump, I'd rather have the pump turn off automatically if he has a stretch of bad weather that does not charge up the battery, than a dead battery.

[SunEagle]

Just confirmed, the table on Page 3 of the manual says the max load current for the SS-6L is 6A, for SS-10L is 10A, for SS-20L is 20A.

I must have missed that info. Thanks for finding it.

You are correct the OP can use even the small 6A CC for his pump since it is only rated 350ma.

I just wanted to make it clear to other readers that a CC will normally not control the operation of the "load" if the battery voltage gets low. That is because most "loads" are connected directly to the battery weather they are AC inverters or DC powered equipment.

[Amy@altE]

Just confirmed, the table on Page 3 of the manual says the max load current for the SS-6L is 6A, for SS-10L is 10A, for SS-20L is 20A.

[Amy@altE]

He said in the OP that it is a DC pump, therefore no inverter and he should connect it to the Load connection on the controller. I believe the LVD current limit is the same as the solar limit. Checking manual to confirm.

[SunEagle]

I'm changing my mind on the charge controller. You shgould get one with Low Voltage Disconnect, so if the battery is low, the pump will turn off. Morningstar SS-6L-12V SunSaver 6A.

Amy

Please clarify your statement about the Morningstar SS-6L-12V CC being able to turn off a pump if the battery is low.

From what I have read that can happen only if the pump is connected to the "load terminals" not if the load is connected to the battery.

While the manual does not give a maximum amp or watt rating for the "load terminals", it does warn that you should never wire an AC inverter to those terminals which could easily overload the output which suggests only a minimal load is allowed.

Do you have any additional data on the maximum size "load" that can be connected to the "load terminals"?

[Amy@altE]

Isc is the max current output under Standard Test Conditions (STC) without a load on it. You want to use that x 1.25 to determine the size charge controller you need. You can go bigger, but not smaller.

The number of hours you use to calculate output are number that equals the output of STC, not the number of hours the sun is up. As you know, the sun is much brighter at noon as it is at sunrise, so not all hours are equal. In Qingdoa, that ranges from 4.23 - 5.55 sun hours. It takes local weather conditions into account, but that's a good question about pollution, I wonder if it accounts for that as well. http://solarelectricityhandbook.com/...rradiance.html

[russ]

Ok so light indoors = useless got. But where do you get the starting rage at 15% ?

Sorry might be a dumb question but first time playing with solar.

Cheers

Solar panels vary in efficiency from maybe 10% for thin film to 20% for the higher efficiency panels for residential use.

For NASA and the military the efficiency can reach 43% though for a high cost.

[Helimadness]

Already one is dealing with something in the 15% efficiency range - now you make that 1.5% efficient = useless.

Ok so light indoors = useless got. But where do you get the starting rage at 15% ?

Sorry might be a dumb question but first time playing with solar.

Cheers

[russ]

Poorly. About 10% of nameplate if you are lucky, is my guess.

Already one is dealing with something in the 15% efficiency range - now you make that 1.5% efficient = useless.

[Mike90250]

...
That brings up another question. How do solar panels handle light from light bulbs? As this is an indoor system when the sun goes down the house lights are on till we go to bed. Maybe that will add some power to the system also? Cheers

Poorly. About 10% of nameplate if you are lucky, is my guess.

[Helimadness]

There are DC pumps specifically designed to work off solar panels. Laing, El Sid / March come to mind. They are about $200, not sure if that's out of your budget, it may be overkill. My gut says the DC pump you have in mind should be ok to run off solar direct, especially since the manufacturer is specifying what size panel to use. It might have a little difficulty starting up in the morning when the sun is low, it needs a good boost to start (don't we all).

To run off the battery, the motor is small enough that it will just draw what power it needs from the battery, so it will be on full or off. You can get a DC timer to control it, like the FlexCharge Timer to turn it of and on, but I think that one just has 8 events (on/off). I think we calculated 1.75Ah per hour, so 12 hours would need 21 Ah battery.

An MPPT charge controller is way overkill for what you need. A PWM will be just fine.

.35A motor x 12V = 4.2W x 12 hours = 50.4Wh. Still don't know where you are, so I'll assume the worst, 2 sun hours (OK, that's not the absolute worst, but close enough). 50.4Wh / 2 sun hours / .67 inefficiencies = 37.6W solar panel. Round up to 40W. A 40W panel has a short circuit current of 2.54AIsc x 1.25 NEC requirement = 3.17A minimum size charge controller. The Morningstar SunGuard 4.5A charge controller would do the trick.

Thanks for the detailed reply. Sorry if I didn't mention before, I am living in China at the moment. Qingdao so about 36 deg north. Sun rise 7:08 am set 5:11 Pm, So about 10 hours. biggest variable on that would be the pollution. Kinda sucks some days. Will be interesting to see the performance difference between a clear day and a full smog day. Certainly highlights the need for better energy and life style living here. The documentary on vertical hydroponic farms really caught my attention on the plane back from xmas holidays. Hence the round about way of ending up here. Sorry off topic.

Most of that above makes sense. To start with I think Im going to run with what I have and go from there. Not really keen on introducing a large battery. Like pointed out before maybe just better to plug into grid. I have an adjustable power supply so can test the min voltage required for it to kick in.
I do have fairly good access to cheap electronics. Browsing around I found this PWM charger and a Battery low voltage cut off for only a couple of bucks each. Sorry all in Chinese, google chrome translates it
Was thinking could use the battery low voltage cut off directly on the solar panels. Its adjustable I think so can just set the panel cut off to match the lower limit for the pump. Not sure if the panels mind having the load cut on and off like that?

http://item.taobao.com/item.htm?spm=a1z09.2.9.81.NaDWTB&id=12898275714&_u=jpoj6se0436

http://item.taobao.com/item.htm?spm=a1z09.2.9.92.NaDWTB&id=19342076310&_u=jpoj6se0dd9

One thing I dont understand about the above it the short circuit current of the panels. Is that the maximum current they can provide? So need a controller above that ??

Paulcheung, as for the fish, there isn't any. The fish pump I am going to use for an indoor hydroponic vertical tower. So just needs a small flow of water to the top where it rains down over the plant roots. The water system is totally enclosed and out of light so slime doesn't grow. The plants are suspended in a mesh basket with some moisture retaining medium supporting them so having water flow 100% of the time I dont think is critical. Still a lot to learn there as well. There is Aquaponics that use fish for nutrients but thats too big a setup for my apartment.

That brings up another question. How do solar panels handle light from light bulbs? As this is an indoor system when the sun goes down the house lights are on till we go to bed. Maybe that will add some power to the system also?

Cheers

[paulcheung]

It is bad idea to run the pump on and off if fishes are in there, the water will get green and dirty and the fishes will get sick. The pump is supply the oxygen and filtering the water, try not turn it off.

[Amy@altE]

I'm changing my mind on the charge controller. You shgould get one with Low Voltage Disconnect, so if the battery is low, the pump will turn off. Morningstar SS-6L-12V SunSaver 6A.

[Amy@altE]

There are DC pumps specifically designed to work off solar panels. Laing, El Sid / March come to mind. They are about $200, not sure if that's out of your budget, it may be overkill. My gut says the DC pump you have in mind should be ok to run off solar direct, especially since the manufacturer is specifying what size panel to use. It might have a little difficulty starting up in the morning when the sun is low, it needs a good boost to start (don't we all).

To run off the battery, the motor is small enough that it will just draw what power it needs from the battery, so it will be on full or off. You can get a DC timer to control it, like the FlexCharge Timer to turn it of and on, but I think that one just has 8 events (on/off). I think we calculated 1.75Ah per hour, so 12 hours would need 21 Ah battery.

An MPPT charge controller is way overkill for what you need. A PWM will be just fine.

.35A motor x 12V = 4.2W x 12 hours = 50.4Wh. Still don't know where you are, so I'll assume the worst, 2 sun hours (OK, that's not the absolute worst, but close enough). 50.4Wh / 2 sun hours / .67 inefficiencies = 37.6W solar panel. Round up to 40W. A 40W panel has a short circuit current of 2.54AIsc x 1.25 NEC requirement = 3.17A minimum size charge controller. The Morningstar SunGuard 4.5A charge controller would do the trick.