I know it's a mess, want advice on how to proceed.

[inetdog]

I settled on the epever 40a (@24v) MPPT + MT-50 + battery temp sensor. https://www.amazon.com/gp/aw/d/B00YC...?ie=UTF8&psc=1

It's still very overcast, but I can see action even at sunset. I currently have 4 x 100w series/parallel at 24v. I have 2 more panels, but when I added them, nothing. I'm going to bring my VOM home tomorrow and check. If I have a bad diode, what are the renogy 100w monos likely to use?

When adding panels does not increase the output current from a CC, the first thing to look at is whether you are in the current-limited BULK stage or the voltage limited ABSORB phase. If you are in ABSORB the output current of the CC may be determined by how much the batteries can take in rather than how much the CC can put out.

If you can turn on a large load on your battery, do that and see if the current out of the CC does increase when you add the additional panels.

[Skunkarific]

Turns out my daughter was looking for a voltage increase rather than an amperage increase. Since she saw the voltage double on the MT-50 when I rewired the 4 panels, she thought she'd see one with six. We tested everything and finally got my 2 batteries charged.

[Skunkarific]

What should be my next move (keeping in mind I've implemented 100% of your ideas), adding batteries (i currently have 2 x 125ah) or a decent sine inverter?

[PNPmacnab]

Believe that MPPT is the same as the Renogy unit. Internals can be seen on the internet. This can be found with slight variations of the front cover. You should have each array string isolated from each other with a diode. In your situation the internal panel diodes do absolutely nothing. Adding a series diode to each string will prevent back feeding from another panel string damaging a panel.

[Mike90250]

Dang !! Another Diode sales pitch, What is it with the diodes? Can you explain how they will work, or are you parroting someones blog somewhere.

Either back up that diode statement with some technical justification from the panel, inverter or combiner mfg, or be quiet about useless diodes turning harvest to heat.


There, having said that, added diodes have no business anywhere in a PV system. not on arrays, not in battery banks, nada. none zilch.

[Skunkarific]

My MPPT is different than a renogy unit in that it does not require a proprietary MT-50 like theirs does. My CC fixes all sins. BTW Mike, any reason not to go full series on all 6 panels and go straight to the controller? It can handle 120v....

[Mike90250]

My MPPT is different than a renogy unit in that it does not require a proprietary MT-50 like theirs does. My CC fixes all sins. BTW Mike, any reason not to go full series on all 6 panels and go straight to the controller? It can handle 120v....

The smallest panels, 18Vmp, have 23Voc. 6 in series gives 138v into the controller. That's more than 120V. It's gonna fry it. I suggest you don't.
3 panels in series, 2 groups of them parallel stays well under the 120V limit. And avoids the need for a fuse, MPPT controllers like to see about 1.5x -2x battery voltage for the PV input, for the best efficiency, The higher the pv voltage is above 2x battery voltage, you start getting more losses in the controller.

[Skunkarific]

Okay! All wired up, 6 x 100W panels wired for 24V, ePever40A controller is really a 35.5A. I replaced the marine batteries with 4 Duracell SLIGC 115s, made a HUGE difference. But in SW Ohio, we are plagued with week-long overcast skies. I only run a couple LED light bulbs and a couple of low wattage laptops, my total consumption is 450 watt hours daily max, usually 350. Still not enough power generated to run my fridge. While adding 250W panels are more economical, I want to keep my ground mounted panels low profile, so I want to stay with 100w PVs. I want to expand, but I want to do it right with your guys guidance. Before I buy panels, I want to upgrade the wiring from the CC (In anticipation of an 80A CC) to 4 gauge. What do you think of this wire:

https://www.amazon.com/gp/aw/d/B00LI...G8U2QKGY&psc=1

And these terminals

https://www.amazon.com/gp/aw/d/B00O5B7GVG/ref=ox_sc_act_image_1?smid=A2TLTYG8U2QKGY&psc=1

I plan to solder them on.

[Laspher]

From my short time here, I can tell you this: Don't solder the terminals, Crimp or just set everything on fire now. Soldered connections tend to be a breaking point, and as strands break, the remaining strands heat up and....well you know.

Then you'll get a post from someone else stating you're getting in the range of buying expensive tools (amazon says $40 so I'm kinda wrong there), or finding someone that can terminate your 4 AWG wires. Past that they will mention buying premade cables (insert suggested shopping link here).

[Skunkarific]

Like this?

https://www.amazon.com/gp/aw/d/B0195VXA10/ref=mp_s_a_1_8?ie=UTF8&qid=1491170331&sr=1-8&pi=AC_SX236_SY340_FMwebp_QL65&keywords=wire+crimper+tool

[Laspher]

Bigger...more like this Longer handles, easier to get the desired pressure.