My Solar Install

AlbertaNewbie wrote:
Update, camping with this system lots. Have seen over 19 amps on direct sun cool days on occasion when there is some sort of load. Usually in float by 9am. Recommend this for any solar newbies

Nice, I've got a similar setup (230 watt conergy panel and sunsaver mppt 15 amp controller) and I was hitting 12-13 amps by mid morning recently without even having to tilt the panel. About 45 amp hours charge per day which I think reflected our power usage. Now if we can just convince those few remaining generator users at the campsite to switch to solar, I can look forward to a quiet cup of coffee in the morning.

Update, camping with this system lots. Have seen over 19 amps on direct sun cool days on occasion when there is some sort of load. Usually in float by 9am. Recommend this for any solar newbies

I think it's more for bugs at the top as it's a great place to build a wasp nest or bee hive due to the added warmth from the fridge.

Thanks for this. In regard to the plastic nut in the fridge vent, I didn't use it, I sized the hole small and threaded the keeper in then used pvc glue to bond the 2 together. After all was done I dicored it as well. Should have just ripped the screen off and used the nut after I dropped the screwdriver through but didn't have any expanded mesh that was light enough to repair.


I don't understand why they put that screen on top under the cover when at the bottom of fridge a small bird could get in through the slots on the door????

KJINTF wrote:
My little 550watt array with the MPPT 60 many times gets me in excess of 40amps to the loads

A lot of variables here, many different camping styles.
Early in the morning battery is low and you run MW, so there is a demand for more than 60 A, but - ops - the sun is low, so charging current stays low. At mid-day there is plenty of sun but there are no loads, you gone fishing, and batteries are floating, so no soup for MPPT 60 again. In the afternoon you are running MW, so there is demand, and if there is still enough sun, then MPPT 60 finally gets his chance to show 42 or 45 A for a few minutes. You move the lunch to a later time because it's too hot, and run MW at sunset, there is a demand again, but - ops - no sun :)

Almot wrote:

AlbertaNewbie wrote:

my single panel is putting out over 16amps, so 3 would put me over the allowable rating of 36amps Isc per the tristar manual. Current rating of the controller must be 125% at or greater than solar arrays short circuit current output (Isc).

Correct estimate though achieved with incorrect methods :)...

The panel is putting out 8.5 Isc, period. 45/8.5/125%= 4-something panels in parallel with 8.5 Isc each.

There is also input Voc limit - 150V? for this unit, don't remember - which means that in series you can't have more than 4-something panels again, because Voc is probably around 30.

But you can't really have 4, here is why. With charging voltage as low as say, 13V, and controller efficiency 5%, and wire losses 2%, the controller will clip the amps when array WORKING wattage (not name plate wattage) hits 45*13*107% = 625W, i.e. 750W will be an oversizing. This is what the Morningstar calculator was trying to tell you.

Now, oversizing isn't necessarily a bad thing. MPPT 45 clipping results in diminishing returns of daily AH when arrays are getting progressively larger than total 45A post-MPPT. But such installs are still possible and often useful, see what Morningstar and other sources say about oversizing the array wattage. This was discussed here a few days ago. My guestimate for safe oversizing with MPPT controllers and flat installs is at least ~10-15% at sea level, i.e. about 720W in your case. Smkettner here has 700W flat array and 60A MPPT, ask if he ever saw more than 40A post-controller ;)

Btw, 10 AWG wire will force you to do series wiring when adding more panels. Otherwise you'll lose some amp-hours.

Alright, off the soap box. A question: how did you attach big plastic nut on strain-relief cable grips (it can't be seen on the photos) INSIDE the crate of the fridge vent?

Thanks for this. In regard to the plastic nut in the fridge vent, I didn't use it, I sized the hole small and threaded the keeper in then used pvc glue to bond the 2 together. After all was done I dicored it as well. Should have just ripped the screen off and used the nut after I dropped the screwdriver through but didn't have any expanded mesh that was light enough to repair.

"Smkettner here has 700W flat array and 60A MPPT, ask if he ever saw more than 40A post-controller"

I would hope he has seen in excess of 40amps from 700watts - I would expect to see as much as the low 50's with his setup

My little 550watt array with the MPPT 60 many times gets me in excess of 40amps to the loads

AlbertaNewbie wrote:

my single panel is putting out over 16amps, so 3 would put me over the allowable rating of 36amps Isc per the tristar manual. Current rating of the controller must be 125% at or greater than solar arrays short circuit current output (Isc).

Correct estimate though achieved with incorrect methods :)...

The panel is putting out 8.5 Isc, period. 45/8.5/125%= 4-something panels in parallel with 8.5 Isc each.

There is also input Voc limit - 150V? for this unit, don't remember - which means that in series you can't have more than 4-something panels again, because Voc is probably around 30.

But you can't really have 4, here is why. With charging voltage as low as say, 13V, and controller efficiency 5%, and wire losses 2%, the controller will clip the amps when array WORKING wattage (not name plate wattage) hits 45*13*107% = 625W, i.e. 750W will be an oversizing. This is what the Morningstar calculator was trying to tell you.

Now, oversizing isn't necessarily a bad thing. MPPT 45 clipping results in diminishing returns of daily AH when arrays are getting progressively larger than total 45A post-MPPT. But such installs are still possible and often useful, see what Morningstar and other sources say about oversizing the array wattage. This was discussed here a few days ago. My guestimate for safe oversizing with MPPT controllers and flat installs is at least ~10-15% at sea level, i.e. about 720W in your case. Smkettner here has 700W flat array and 60A MPPT, ask if he ever saw more than 40A post-controller ;)

Btw, 10 AWG wire will force you to do series wiring when adding more panels. Otherwise you'll lose some amp-hours.

Alright, off the soap box. A question: how did you attach big plastic nut on strain-relief cable grips (it can't be seen on the photos) INSIDE the crate of the fridge vent?

The voltage sense wire is something you supply

Use a small say 22awg stranded wire pair and a 1 amp or less fuse at the battery side just to keep the wire from burning up if it got shorted someplace along the run

Depends on how long and what size main wire you have from the controller to the battery the sense line helps a lot it will easily compensate for 300mv or more loss in the wire - suggest you take a measure measurement with an accurate volt meter across the main wire from the controller to the battery while charging - might be surprised with the amount of voltage loss

AlbertaNewbie wrote:

EsoxLucius wrote:
The TS-45-MPPT can accommodate 800 watts NOCT. So three 250 watt panels is possible.

http://www.amsolar.com/home/amr/page_164

Yes, however my single panel is putting out over 16amps, so 3 would put me over the allowable rating of 36amps Isc per the tristar manual. Current rating of the controller must be 125% at or greater than solar arrays short circuit current output (Isc).

I also plugged the panel specs into morningstars string calculator and both in series and parallel with 3 modules it exceeds max solar input.

Put the added panels in series and your Isc does not increase.
Four panels would need to be series/parallel and power to the battery would be clipped at 45 amps. MS MPPT is designed to operate all day at 45amp rating. The string calculator is a bit conservative with wattage. Primary issue to avoid is max Voc.

Morningstar MPPT Controller's Maximum Input Power Rating

I can't imagine you would need more than two panels so mostly this is just theory talk.