Solar Charge Controller

Niner,

Which ebay adjustable controller did you buy? Could you post a link? That is one thing I would like to have.

steveh27 wrote:
I discovered why my multimeter wouldn't show the Short Circuit Current (SCC). The 20 amp fuse was bad. I did check behind both panel's black boxes & the connections are good. One registered Open Current Voltage (OCV) of 21.2 the other 20.8. It's rated at 21.8. The rated SCC is 7.2 amps with max output of 6.67 amp.

Results:

SCC from controller connection = 6.5
from 25' 18 ga = 6.7
from 22' 10 ga = 6.6

I need to make the final solder & heat shrink connections on the 10 ga. wire. I may shorten it a bit to 16-18' if that needs done & would help.

Now my battery has a SOC of 87% with 12.7 v and a draw of -0.2a. When connected with the various cords my Trimetric shows:
with 25' 18 ga = 13.1 v and +2.9a
with 22' 10 ga = 13.2 v and +3.0a the v went up a bit the longer connected
with 16' 18 ga battery clamped direct to battery = 13.3v and 3.0a.

Maybe all is well & I just do not drain the battery enough to allow all the amps to charge?

If you are at 87% SOC, then yes, the amps are going to drop quite a bit. The only way to get around that is to have an adjustable charge controller that you can set the bulk and absorption charge Voltages higher, to like 14.8 or 15.0V. If you do that, the amperage level will stay higher longer, and your battery's state of charge will get higher too, before going into maintenance mode and voltage drop to 13.4 -13.8V, for top charging.

Which is exactly what I did with my 120W portable solar panel. I bought a Solar 30 PWM charge controller on Ebay for $31, with adjustable voltage setting for bulk, temperature controlled, and I set it at 15.0V for my Trojan T-1275, a 12V 150 Ah Sweeper/golf cart battery. I will maintain 5.5 to 6.1 amps charge rate for a long time, and it does get my battery darn near topped off, almost every single day. 6 amps for 7 hours, is about 42 Ah, plus what ever else I get at sunrise and sunset, aiming the portable panel at the sun a few times a day.

I discovered why my multimeter wouldn't show the Short Circuit Current (SCC). The 20 amp fuse was bad. I did check behind both panel's black boxes & the connections are good. One registered Open Current Voltage (OCV) of 21.2 the other 20.8. It's rated at 21.8. The rated SCC is 7.2 amps with max output of 6.67 amp.

Results:

SCC from controller connection = 6.5
from 25' 18 ga = 6.7
from 22' 10 ga = 6.6

I need to make the final solder & heat shrink connections on the 10 ga. wire. I may shorten it a bit to 16-18' if that needs done & would help.

Now my battery has a SOC of 87% with 12.7 v and a draw of -0.2a. When connected with the various cords my Trimetric shows:
with 25' 18 ga = 13.1 v and +2.9a
with 22' 10 ga = 13.2 v and +3.0a the v went up a bit the longer connected
with 16' 18 ga wire clamped direct to battery = 13.3v and 3.0a.

Maybe all is well & I just do not drain the battery enough to allow all the amps to charge?

steveh27 wrote:
I seem to have a problem with my 120 watt portable:

http://www.amazon.com/Infomon-Monocrystallline-Portable-Folding-Solar/dp/B005WMD8VY/ref=cm_cr-mr-title

I've had it 2 years & only used it a few times. I was getting up to the 6 amps it puts out, but now I'm only getting up to 3 amps.

It has this cheap controller:
http://www.ebay.com/itm/Solar-Charge-Controller-Overloading-Short-circuit-Reverse-Discharging-Protection-/300916227986?tfrom=301218792237&tpos=top&ttype=coupon&talgo=undefined

This year I did install a quick disconnect plug to the battery through the box for easy plug in. That 1 foot short wire is 18 ga.

The 2 wires I used before came with the panel are 18 gauge. 1 is 15 foot long with clamps for the hookup. The other is a 25' extension with the quick disconnect plugs. I just put together a 10 gauge wire 22' foot long with the quick disconnects. All 3 wire hookups give me only up to 3 amps, even the clamps direct to the battery. Yesterday I checked the panels Open Current Voltage & it was over 20 volts even through the 25' extension. It's rated at 21.8 I could not get my multimeter to work checking the Short Circuit Current amps. (I'm a novice with it). It's rated at 7.3. I did clean the panel, no change.

Today I hope to check the SCC amps with the multimeter, and cover one of the panel sides to see if either is not connected properly. Any other ideas?

Sounds to me like you are only getting output from one panel out of the two folding panels. Time to check all the electrical connections, starting with removing the covers off the black boxes of each panel, before the charge controller. Get a DC amp clamp, and clamp it over each red wire while solar panel is directed at the sun, while trying to charge your battery when it needs a deep recharge and tell us what each panel flows for amps.

wbwood wrote:

JiminDenver wrote:
My twin 245w set ups are only different in that one has a 25 ft set of 10 awg cables, the other fifty feet. The system with the longer cables is always a few 10ths of a amp lower than the shorter. Worth it because the longer set up is easier to avoid the shade with.

wbwood

Every rig/user is different so it's hard to say this will be enough. We used a 230w system last year for the loads you are talking plus a considerable amount of furnace run time. It was overkill even with the afternoon storms we had except for one cold and cloudy weekend, and even then it kept us off the generator.

Some of the places have 200w kits for $300 including shipping. I would toss the mounting hardware, hinge the panels and run the cable to the controller near the batteries. A little more work than the premade portables and twice the power.

We are not going to mount the panels...I am leaning towards getting 2 - 100 watt panels and hinge them as you mention. It's just as cheap (if not cheaper) to get a kit with the controller. Usually it's a 30 amp PWM controller. One kit has a 20' cable, but some of the others don't mention it. I know they sell different length of cables. I'm looking at getting a quick connect/disconnect and mounting it underneath (or there abouts) near my batteries. That way, I can just pull out the panels, place and point them in the right direction and plug it in.

We don't do a lot of dry camping. (Actually have only done it once in the last year), but want to be able to do it and not have to run the generator if we don't want to or need to. We are not trying to power everything in the coach and not for extreme periods of time. The 30 amp controller states you can go up to 400 watts. So that gives the ability to add another panel or two later on. When the 2 group 27's die, we will replace with a couple of 6 volts...so that will help a little more. By then, who knows, we may be true solar converts....lol

I just want something to play with, learn with and help out some. I also like the idea of possibly starting a battery bank at the house and being able to use the solar panels and an inverter to run a few things with power outages. We have a small portable generator at home to use, but we get a lot of sun, so why not harvest it!

Depending on what you can get the panels for you may be able to beat the kit cost or at least get better quality components. My 25 ft set of cords with connectors was $32 shipped and the 59 ft were $50 or so. Longer and heavier than those in the kits. BFL uses a inexpensive PWM controller that would work well. Newer ones can use a temp probe too.

ktmrfs wrote:

BFL13 wrote:
Doesn't have to be "hot climate" to lose amps with MPPT due to panel temperature over PWM in same situation.

Here, east side of Vancouver Island, by the sea, cool breezes, with 230w tilted up (no heat trap underneath) and MPPT, ambient at 16C, I was getting 15.5a to battery, panel temp was 44C. (measured with IR looking up at white part under a tilted up panel)

At ambient 25C nice summer day for here, panel temp now 51C and amps are 13.5 instead of 15.5. (PWM would be 14.5) So we have gone from being 1 amp more than PWM in the Spring to being 1 amp below PWM in Summer.

Some solar info dug up by Googling, says you lose about 10% with MPPT when panel temp is 50C, so my 13.5 vs 15.5 comes out in ballpark where 2/15.5 = 13%

Hate to think what the results would be in a "hot climate" in the summer :)

BTW, the panel specs are for panel temp of 25C standard test conditions. How can they get the panel temp that low? Ambient would be near freezing to get panel temp 25C it seems.

BFL:

I think from your posts on measurements, your using the Trimetric conroller readout for current. That's fine for MPPT controller, since the output is DC. for a PWM controller, the output is usually a pulsed Current (Pulse width modulation). That poses a problem getting an accurate current reading with the trimetric. Been there, done that. The issue is your using a DC current meter to measure and AC current. The trimetric will measure the peak current, NOT the RMS current. To really compare the two controllers you would need to measure the output of the PWM controller with a true RMS current probe, which the trimetric is not. I ran into this early on and the trimetric in my case, with a morningstar PWM controller read a noticeably higher current than measuring with a true RMS current probe.

True, the MPPT output current dropped with temperature, but it still outperformed the PWM, even at 100F, but by then the difference was only a few %.

I used my digital multimeter for Isc at the panels, the ammeter read-outs on the Solar30 (PWM) and Eco-worthy (MPPT) and the Trimetric at various times. I cross-checked to see if amps were out of calibration, got same amps. No idea about RMS it is all DC amps. I don't think the multi is RMS, reads low on MSW inverter output. So the others must not be either since the amps match.

I won't have final proof of what I am seeing until ambients get down to 16C again, and amps come back up to what they were in Spring or not. If we are still using solar then. Summer is nearly over--sob!

The only time I have seen a difference in output with my panels is when it is sub freezing. The 220w mono saw 12.75a instead of the 12a I see at any other temperature including 90s and above. Then again it could have been as simple as the air on a clear cold day is cleaner than on a smoggy, hazy summer day.

JiminDenver wrote:
My twin 245w set ups are only different in that one has a 25 ft set of 10 awg cables, the other fifty feet. The system with the longer cables is always a few 10ths of a amp lower than the shorter. Worth it because the longer set up is easier to avoid the shade with.

wbwood

Every rig/user is different so it's hard to say this will be enough. We used a 230w system last year for the loads you are talking plus a considerable amount of furnace run time. It was overkill even with the afternoon storms we had except for one cold and cloudy weekend, and even then it kept us off the generator.

Some of the places have 200w kits for $300 including shipping. I would toss the mounting hardware, hinge the panels and run the cable to the controller near the batteries. A little more work than the premade portables and twice the power.

We are not going to mount the panels...I am leaning towards getting 2 - 100 watt panels and hinge them as you mention. It's just as cheap (if not cheaper) to get a kit with the controller. Usually it's a 30 amp PWM controller. One kit has a 20' cable, but some of the others don't mention it. I know they sell different length of cables. I'm looking at getting a quick connect/disconnect and mounting it underneath (or there abouts) near my batteries. That way, I can just pull out the panels, place and point them in the right direction and plug it in.

We don't do a lot of dry camping. (Actually have only done it once in the last year), but want to be able to do it and not have to run the generator if we don't want to or need to. We are not trying to power everything in the coach and not for extreme periods of time. The 30 amp controller states you can go up to 400 watts. So that gives the ability to add another panel or two later on. When the 2 group 27's die, we will replace with a couple of 6 volts...so that will help a little more. By then, who knows, we may be true solar converts....lol

I just want something to play with, learn with and help out some. I also like the idea of possibly starting a battery bank at the house and being able to use the solar panels and an inverter to run a few things with power outages. We have a small portable generator at home to use, but we get a lot of sun, so why not harvest it!

BFL13 wrote:
Doesn't have to be "hot climate" to lose amps with MPPT due to panel temperature over PWM in same situation.

Here, east side of Vancouver Island, by the sea, cool breezes, with 230w tilted up (no heat trap underneath) and MPPT, ambient at 16C, I was getting 15.5a to battery, panel temp was 44C. (measured with IR looking up at white part under a tilted up panel)

At ambient 25C nice summer day for here, panel temp now 51C and amps are 13.5 instead of 15.5. (PWM would be 14.5) So we have gone from being 1 amp more than PWM in the Spring to being 1 amp below PWM in Summer.

Some solar info dug up by Googling, says you lose about 10% with MPPT when panel temp is 50C, so my 13.5 vs 15.5 comes out in ballpark where 2/15.5 = 13%

Hate to think what the results would be in a "hot climate" in the summer :)

BTW, the panel specs are for panel temp of 25C standard test conditions. How can they get the panel temp that low? Ambient would be near freezing to get panel temp 25C it seems.

BFL:

I think from your posts on measurements, your using the Trimetric conroller readout for current. That's fine for MPPT controller, since the output is DC. for a PWM controller, the output is usually a pulsed Current (Pulse width modulation). That poses a problem getting an accurate current reading with the trimetric. Been there, done that. The issue is your using a DC current meter to measure and AC current. The trimetric will measure the peak current, NOT the RMS current. To really compare the two controllers you would need to measure the output of the PWM controller with a true RMS current probe, which the trimetric is not. I ran into this early on and the trimetric in my case, with a morningstar PWM controller read a noticeably higher current than measuring with a true RMS current probe.

True, the MPPT output current dropped with temperature, but it still outperformed the PWM, even at 100F, but by then the difference was only a few %.

My twin 245w set ups are only different in that one has a 25 ft set of 10 awg cables, the other fifty feet. The system with the longer cables is always a few 10ths of a amp lower than the shorter. Worth it because the longer set up is easier to avoid the shade with.

wbwood

Every rig/user is different so it's hard to say this will be enough. We used a 230w system last year for the loads you are talking plus a considerable amount of furnace run time. It was overkill even with the afternoon storms we had except for one cold and cloudy weekend, and even then it kept us off the generator.

Some of the places have 200w kits for $300 including shipping. I would toss the mounting hardware, hinge the panels and run the cable to the controller near the batteries. A little more work than the premade portables and twice the power.