New Member

[Greg Shaw]

Hello everyone, I am a new member, as the title suggests, and have numerous questions regarding setting up and wiring my solar equipment. Is this the proper forum to use ?

[Greg Shaw]

I guess I'll just jump right in. Little back ground info first equipment wise:

- 8 Hanwha Q.PEAK DUO BLK-G6 + 365 Watt 60 Cell modules
-Midnite solar 150 MPPT charge controller 150VDC in, 96A out, (12 to 72V battery)
- Samlex EVO - 4024 24V DC 4000W pure sinewave inverter/charger
- 8 6V Rolls-Surrette S6 L16-HC deep cycle flooded lead acid batteries

This is being set up at a off grid cottage to be used as a summer home. Fridge and stove presently propane and electricity provided by 4500W generator.

At this point I need advice on the initial wiring for the system. Primarily wiring of modules (2, 4 in series ??) , wire needed to run from ground mount modules to power shed (approximately 120 ft) configuring of batteries (12V , 24V ??) and wire needed to run from power shed to cottage (approximately 100ft.)

Very basic info needed at this point as I am a far cry from being up and running. Will not be until next spring/summer due to having no winter access. Just trying to get the underground cable in place first, build racking etc. Trenches are dug and conduit is in place ready to pull wire.

Any advice/feedback would be greatly appreciated.

[Ralph Day]

I can run my whole house on Surrette S550's (L 16) in the summer. In the winter and shoulder seasons it's hybrid utility and renewables. That' with a chest freezer and 2 fridges as well as all the other things to live with...lights, water, entertainment etc.

I'd suggest you stick with the propane stove. A good electric fridge as a replacement. Water heat? I have a Takagi tankless. Endless hot water as long as you have propane and the minimal power to run it (40 watts running).

Good luck.

[Rob Beckers]

Hi Greg,

To answer some of the wiring questions: The Classic-150 has a maximum input Voltage of 150V, and a 60-cell panel in our general area can go up to around 45 Volt at -35C. So, maximum string length is 3 panels. Of course, with 8 panels you can't do strings of 3. That puts it at 4 strings of 2 panels.

The 24V battery bank will need at least 2 of the 60-cell panels in series to allow proper charging, which works out with the previous 4 strings of 2.

For wiring from the array to the charge controller, each string adds around 9 Amp peak, so 4 strings is 36 Ampere. We like to see 5% peak-loss or less for off-grid solar systems, in reality that means actual losses are quite a bit less since panels rarely produce rated output. Running those numbers that puts the wire size between array and charge controller at 6 AWG (for 4.2% peak-loss), of if you want to save money 8 AWG will do 6.7% peak-loss.

If you can get another panel and do 9, you can go to 3 strings of 3. The Classic can easily handle that, in fact with 3,285 Watt you would only see very occasional clipping (at 100A, the maximum for the charge controller). The wiring size would drop down to 8 AWG for 3.3% peak-loss or 10 AWG for 5.3% peak-loss.

-RoB-

[Greg Shaw]

Ralph and Rob thank you for the responses.

Ralph I will be staying with the propane stove knowing how much a electric would draw and because we like the propane. We will be looking to get a electric fridge once we have tested out the solar for a summer and will be using on demand propane hot water, I'll be looking into the Takagi you have suggested.

Rob again thank you for your advice. I will be staying with the 8 panels for now and wire as 4 strings of 2. 6 AWG works for me, money not being a issue to any great extent. If I read your post correctly you are suggesting/saying I wire my batteries in series at 24V correct.

One more question for now, when I run the wiring am I running 1 pair of 6AWG wires (- +) or am I also running a third for a ground wire from the panels back to the power shed.
I would think that I would use a ground rod (one at panels and one at power shed) but not really sure.

[Rob Beckers]

Greg, you mentioned having an EVO-2024 inverter, which is 24 Volt. So, yes, you would HAVE to wire your batteries as a 24 Volt bank. With 8x S6 L16-HC (S-550) batteries that means 4 in series, and two of those strings of 4 in parallel.

This image shows the correct wiring:

https://us.v-cdn.net/6024911/uploads/265/VNUQOQCUKAW4.png

Note how the positive wire to the inverter comes from the top string, while the negative inverter wire comes from the bottom one. This is important, to spread the current better between the two strings of batteries.

-RoB-