LV6548 Panel Suggestions

[medic149]

I have an MPP LV6548 that I hope to get installed this spring at our off-grid cabin. After all of my battery debacles and other shipping issues, I want to try and get a jump on the panels.

Looking for suggestions on which panels are working the best for you and your LV6548.

I will most likely to 2 series of 6 panels, one series for each PV input, for a total of 12 panels.

Currently looking at these because they seem to be a pretty good buy: https://www.signaturesolar.com/prod...717&utm_medium=email&utm_source=shopify_email

Any suggestions are greatly appreciated.

Thanks

 

[sunshine_eggo]

I'm not a big fan of the Voltronix 250V MPPT. You have to hit things perfectly to get the 4000W input.

6S panels @ 246V is WAY too close to the 250Voc limit unless you NEVER see temps below about 65°F
2P will have a 21.06A Imp meaning you'll automatically lose those 3.06 amps if you ever get them.

Thus a 5S2P (3650W) array of those panels is limited to 34.2Vmp * 5 * 18A = 3078W absolute maximum.

Need a 60 cell panel with Imp= 9A and Vmp around 30V.

 

[Lt.Dan]

I agree the 250v max is still in the weird stage. It is so hard to find the perfect panel that will maximize potential with the LV6548.

Edit: the best panels i have found are the SanTan T Series 250w panels. They are 37.6V VOC, and the LV6548 can safely handle a 6s3p array per input. 37.6v comes out to about 220v, which leaves good headroom for low temps, and the 3p makes amperage (in my real world findings) 21a. The inverter does clip at 17.5a, but it still creates good numbers, and the panels are so cheap I don't mind loosing the couple amps.

 

[Zwy]

Around the 350W range works well, the panels you linked will work but you can't go 6S, only 5S. Just be certain to figure VOC in cold temps if your area experiences cold weather. You can try to game it but the amps limit will get you every time, you should be fine with 5S2P for each input with ISC at 22A but that is pushing it slightly. SCC may clip slightly. With both inputs, you would be in the 7200W PV size, pretty close to the 8000W limit.

Here's a recent post I had for panel selection, there are others. https://diysolarforum.com/threads/should-i-use-solar-combiner-boxs.35263/post-442462

 

[medic149]

Around the 350W range works well, the panels you linked will work but you can't go 6S, only 5S. Just be certain to figure VOC in cold temps if your area experiences cold weather. You can try to game it but the amps limit will get you every time, you should be fine with 5S2P for each input with ISC at 22A but that is pushing it slightly. SCC may clip slightly. With both inputs, you would be in the 7200W PV size, pretty close to the 8000W limit.

Here's a recent post I had for panel selection, there are others. https://diysolarforum.com/threads/should-i-use-solar-combiner-boxs.35263/post-442462

Thanks Zwy!! That was my concern. Trying to figure out all the calculations last night was making me insane. lol

 

[medic149]

I agree the 250v max is still in the weird stage. It is so hard to find the perfect panel that will maximize potential with the LV6548.

Edit: the best panels i have found are the SanTan T Series 250w panels. They are 37.6V VOC, and the LV6548 can safely handle a 6s3p array per input. 37.6v comes out to about 220v, which leaves good headroom for low temps, and the 3p makes amperage (in my real world findings) 21a. The inverter does clip at 17.5a, but it still creates good numbers, and the panels are so cheap I don't mind loosing the couple amps.

I was actually looking at these last night as well. Out of stock of course. It's been hard enough trying to find the right panel with the right numbers for the LV6548, but stock issues making it even harder. Thanks Lt. Dan! You've always got some great info.

 

[medic149]

I agree the 250v max is still in the weird stage. It is so hard to find the perfect panel that will maximize potential with the LV6548.

Edit: the best panels i have found are the SanTan T Series 250w panels. They are 37.6V VOC, and the LV6548 can safely handle a 6s3p array per input. 37.6v comes out to about 220v, which leaves good headroom for low temps, and the 3p makes amperage (in my real world findings) 21a. The inverter does clip at 17.5a, but it still creates good numbers, and the panels are so cheap I don't mind loosing the couple amps.

Actually, never saw these before. I learn something new every time I do research! https://store.santansolar.com/product/santan-solar-t-series-250w-snail-trails/

 

[Lt.Dan]

I have 24x of the snail trail panels, and while they aren't top notch quality, you seriously can't beat their price.

Also, calling santan is always best. They're website isn't always updated on their inventory, so talking with them over the phone is best.

 

[medic149]

After doing more research, I'm trying to figure out if I should stay with a 250w or try to go higher, with still trying to stay within the LV6548 parameters. I would like to have the fewest panels as possible, but still enough to charge the batteries up as much as possible. Seems like everything I find in the 300 or even 400-watt range, has way to high VOC for the LV6548.

I live in upstate NY and get around 3 to 3.5 hours of direct sun per day, with various amounts of shading throughout that time period because of some trees. Some more trees may be coming down though.

I've increased my battery capacity and now have 2 - 48V 100AH LCD Battery by EG4 and a generator to add to the grid side of the LV6548 to charge up when needed. We currently have very little draw with only 2 LED table lamps and a small dorm fridge. In the future, we will probably have a little bigger fridge and maybe a few other electrical items that will increase the draw.

Does anyone have any thoughts??? Stick with 250's or try to find something higher?

 

[Zwy]

If you are going ground mount, then really it comes down to what you're willing to pay. If roof mount or something like an RV with limited space, then it comes down to getting the largest panel to fit in the space.

 

[medic149]

If you are going ground mount, then really it comes down to what you're willing to pay. If roof mount or something like an RV with limited space, then it comes down to getting the largest panel to fit in the space.

Definitely ground mount. I don't mind paying extra to have a decent system to fit my current and future needs. As much as I would love to buy some good used panels at $60 a piece, I also don't mind buying new ones for higher watts and lower panel quantity. I actually just came across one of your other posts https://diysolarforum.com/threads/should-i-use-solar-combiner-boxs.35263/#post-442462

That post has me thinking about moving higher to the 340-watt range and doing a 5S2P in one PV input of the LV6548.

 

[medic149]

I actually found this calculator, which is helping me understand this more: https://www.diyrenewable.com/charge-controller-calculator/

This shows a 5S2P with the Canadian Solar 340's would give me minimum 265 volts, which is over the 250 threshold. My concern is in the colder months.

Just found these that might be a good fit for the LV6548 https://www.signaturesolar.com/products/365w-60cell-black-mono-solar-panel-by-solarever. With a 5S2P, it looks like these would give me 3650 watts at 239 volts......

 

[Zwy]

I ran the Canadian Solar 340W thru Midnite's calculator https://www.midnitesolar.com/sizingTool/ with the temp coefficient's and yes, VOC at cold temps would put you over.

The 365W from Sig Solar would be 240VOC at -22F, 304V at -40F.

If you go 5S2P, you will have to Y and input into both PV inputs.

 

[medic149]

I ran the Canadian Solar 340W thru Midnite's calculator https://www.midnitesolar.com/sizingTool/ with the temp coefficient's and yes, VOC at cold temps would put you over.

The 365W from Sig Solar would be 240VOC at -22F, 304V at -40F.

If you go 5S2P, you will have to Y and input into both PV inputs.

I hadn't thought about doing a Y at the PV inputs until I saw your post. Is there any disadvantage to that?

 

[Zwy]

I hadn't thought about doing a Y at the PV inputs until I saw your post. Is there any disadvantage to that?

I'm wiring mine that way, otherwise I have to run 4 circuits. That would be 8 wires.

Doing the Y only requires 4 wires. Kromc5 has his wired this way, that is where I learned about it.

 

[medic149]

I'm wiring mine that way, otherwise I have to run 4 circuits. That would be 8 wires.

Doing the Y only requires 4 wires. Kromc5 has his wired this way, that is where I learned about it.

Are you going to use a PV junction box with surge protection? I just read that in the manual.

 

[Zwy]

I'm looking at the Watts247 4-2 Combiner, he has other models available too. https://watts247.com/product/solar-panel-combiner-box-4-circuits-to-2/

I have looked at various disconnect switches and wanted fuses so it fit my system well. I will have 4 strings of 530W panels arranged as 4S. The 4-2 works perfectly combining 2 strings and 2 PV circuits to charge controllers. I may have to change out the breakers as 63A is overkill for what I need.

For your situation, it will depend on how many panels and how you want to series connect such as 4S or 5S. 5S2P would be 10 panels but would need something like the 8-2 combiner. You can build you own but I've found by the time I buy all the components, it was cheaper for me just to buy one of Ian's.

 

[medic149]

That looks like a pretty nice combiner box. All-in-one is nice. After working on this for the past 2-days, I am leaning towards the 5S2P with 10 panels.

 

[Zwy]

That looks like a pretty nice combiner box. All-in-one is nice. After working on this for the past 2-days, I am leaning towards the 5S2P with 10 panels.

2P doesn't require a combiner box, you could just have a fused disconnect but you would need a 4 pole as both negative and positive from the panels need to be switched. Should be easy to find something outdoor rated (Type 3 or 4) on ebay, used or new. Look for 4 pole switch.

Or you can go with the 4 to 2 combiner box, just that you would have unused spaces on each side.