M-4 Plugs, or Chop'm Off

RJsfishin wrote:
I've got 2 panels mounted, even made'm tiltable. And I got a 10ga twin lead down the fridge vent.
Now I'm lookin at the M-4 plugs layin all over. What makes me want to chop'm off, and mount a couple watertite junction boxes ? Is that the way to go ?
Do the boxes have screw terminals inside them, or solder everything ?

The junction boxes on my panels can be opened up and inside there is a terminal strip. I removed the pigtail MC4 wires and attached my wiring.

With two higher voltage panels in parallel, I used these instead of a combiner box:

Just leave them long with a few holes along the strut. You'll find out how critical a few degrees of angle are with 200W.

While in Winter storage, I leave mine at 58 degrees, at Lat. 45. Of course, I'm battling snow up here so the more angle, the merrier. I wouldn't swear to it but I'm probably getting a little boost off the snow or roof reflection when tilted, also. I've never messed around with different angles in storage because 1. The panel charges the batteries at any angle 2. I'm lazy.

Thanks for all the calculations etc. I don't see myself getting all that critical w/ the tilting. I think my tilt bars I have will do about 50 degrees max. So we'll see how that works for this year. I'll have 200 watts on the roof, and still use my 90 watt panel on the sun tracker mount if/when needed.

2oldman wrote:

BFL13 wrote:

2oldman wrote:
For the winter months I'm usually sitting at about 60° tilt.

What Lat are you at in the winter months though?

Palm Springs latitude.

So using Lat 34N to make it simple, then on 21 Dec with Dec about 23.5S, tilt at noon would be 57.5 degrees ( your 60 degrees.) Then tilt reduces by 8 degrees a month till on 21 March it is 34 degrees.

21 Jan would be about 50 degrees. I see macslab says in winter optimum tilt is Lat x 0.89 plus 24 degrees. So 34 x.089 = 30.26 plus 24 = 54.26.

So he is taking declination for the winter three months to be 54.26 - 34 = 20.26S which is only 3 degrees (one and a half weeks) after 21 Dec. IMO that would make the tilt a little high for most of the winter, especially in March, when daylight is longer and you do get some shoulder hours light that needs the panel lower to see it.

So all in all you have a range of tilt for Palm Springs from 57.5 at Xmas to 34 if you stay till 21 March. Pick a tilt somewhere in the middle of that for most AH or figure it out for your actual dates there.

RJsfishin wrote:
Made easy work of the wiring, chopped off the MC-4s, and soldered them all together. Then liquid taped the soldered connection. Another coat or 2 will have the connection completely waterproof. Then a blob of Dicor over the connection, anchoring it all to the roof. I see no need for boxes

Series or parallel? You only need the box for parallel wiring.

For series you don't need a box, and neither you need to chop the connectors off or solder anything. I see the damage has been already done :), but you didn't have to. Here is what people do: Buy 50ft or 100ft MC4 extension #10 or #8 and connect to MC4 on the panels pigtails. These connectors are waterproof. You may hide it under the panel to protect from UV, though not absolutely necessary. Then run it all the way to controller, where you use the bare end or a spade terminal. You would still have to chop MC4 extension approximately in the middle, so the length of extension should be equal to double distance to controller.

Tilt... With today's panels prices it has lost popularity. Tilt makes a lot of sense for people with small portable panel that can't get enough juice, and they are usually getting an added bonus with some tracking, not just tilting. For permanently roof-mounted panels - get more panels and forget about it.

BFL13 wrote:

2oldman wrote:
For the winter months I'm usually sitting at about 60° tilt.

What Lat are you at in the winter months though?

Palm Springs latitude.

2oldman wrote:
For the winter months I'm usually sitting at about 60° tilt.

What Lat are you at in the winter months though? I see Moses Lake is at 47N so 60 degrees would be right for Dec at 13S.

For the winter months I'm usually sitting at about 60° tilt.

RJ, proper tilt changes by 8 degrees a month so you might want to have some holes for different tilts depending on how fussy you feel like being once you are set up there. I am supposing you will park so the tilted up panels face South.

If you are staying for three months you could just pick the optimum angle for the middle month and not lose much.

You pick your tilt angle for high noon at that latitude and then lower it by some so it gets more light in the shoulder hours. However when daylight time is short as in winter, there are no shoulder hours, so just leave it at noon angle based on your Lat and Dec. Macslab website has the optimum angles for that for various locations

The angle changes by 8 degrees a month as the sun's Declination changes through + 23.5 to - 23.5 every six months. So Dec is zero twice at 21 Mar and 21 Sep when tilt = Lat.

If you are parked from 21 Dec to 21 March you could pick your angle for 21 February when Declination is say - 13 degrees (WAG) and your Lat is 33N (or whatever it is at Q)

So at high noon tilt would be 33 plus 13 = 46 and you might as well leave it there with hardly any shoulder hours that time of year.

That is for the fixed tilt panels facing South. It is the opposite for your twirling panel's tilt, which you need to be at the proper noon angle but go higher earlier and later in the day when the sun is lower.