Solar Tracker Project

[Xringer]

I was just looking at the amps into the 10 ohm load.. 6.8A = 462.4 watts.. (+10 lost=472) is about 94% of the rated power!

But, until today this week has been a real buzz-kill.. Hardly any sun..

Just guessing, I would say the system might be capable of 2 to 2.7 kw of DC output per day.
Long Sunny day that is!!

I do have a device to measure daily production, http://ecorenovator.org/forum/applia...pv-panels.html
But it's limited to 60v, so I can't use it while the array is in the Series configuration. (80v open).

I was thinking about buying 4 more panel connectors, so I could measure each panel, one at a time.
Then, I could just leave the meter on one panel and multiply the watthours by 4..
Or, monitor 2 panels and multiply by 2..

~~
Anyways, I've been thinking about investing in some back-up.
Looking at the idea of a MPPT 48v battery charger to make DC.
(Which I could measure with my new meter).
And use that 48v into my back-up inverters for AC, or direct into backup DC lighting etc.
I need read up on batteries before making up my mind..

[Xringer]

Since the shadows are starting to fall on the panels, we got some ropes and
tugged the array back down to the old dish location. (A come-along helped).
Moving that old platform into the woods was a real PITB (B=Back).

I know that far-back location is NG for summer, since the over-hanging
branches get so long..
So, maybe I'll used the rope saw next spring, on some of those high limbs.



No sun yet today..


It's a few feet to the west and slightly south of the original mount location.
I had to add about 10 feet to the DC cable (coax), so there will be some power loss.
I've got two (almost new looking) 100' cables that I plan to install.
In parallel, they should cut the series resistance in half..
Just need to work out the connection details.

~~~
Since I have the old TVRO cables out there, I'm thinking of installing two more 10w panels.
They will be wired to chargers in my ham shack, keeping the old car batteries up to the full mark.

~~~
Edit, Oct 16, 2010:
This morning the sky cleared! At high noon I checked the current into the 10 ohm load.
Over 7 amperes! That's 490 watts (98% of rated)!
Add 10watts of line loss and the panels are putting out their full rated power of 500w.

[Xringer]

So now I can get my old batteries back up to a good SOC..

I used the old cables from the TVRO line..

Now the array feels like it's balanced better, when I adjust the elevation..

[RyanTheHandyman]

This is unrelated but this is the only way I know how to ask you a question directly Xringer. I was interested in your pages regarding the MTM Solar Tracker Circuit. I was wondering if you had any more pictures of the circuit board front and back side. Also any likes and dislikes you have about the circuit.
Ryan

Go Green America!

[Xringer]

Hi Ryan,

The MTM tracker uses relays. I have found (as well as one other poster here) these relays are okay
for a short demonstration or school science fair project, they don't last very
long in actual use on a solar array.

Due to shadows, clouds, your actuator's motor, gear box and the mechanical backlash of the parts, the relays take a beating.
Contacts clicking open and closed many thousands of times a day.

I found the photocells provided with the kit, would not operate at higher
temperatures, and could even be permanently damaged by solar heat.

When the MTM board was working, it was extremely accurate, way more
precise than is actually needed in a polar mount tracker.

I have no pictures of the bottom side of the board, and I was asked by the vendor, not to disseminate the schematic diagram.

I really can not recommend using this board on an array that's going to be
moving a heavy load (my array is about 150 pounds).
The relays just don't seem to be able to take the wear.
If I ever do repair my board, I'm thinking of replacing the relays with
a power MOSFET 'H' driver circuit.


I have been using the RedRock board for a while now, and so far it's working
very well. All I'm worried about now, is the actuator wearing out.


Last week, I measure 507 watts at the load!! Which isn't bad for a 500w array of some poor looking panels..

[Daox]

Woo, missed this one but found it again.

BTW, what are you using the power from these batteries for? I thought it was going directly to the boiler heater thingy you have setup?

[AC_Hacker]

Xringer,

Have you been able to determine what your actual typical weekly power is from your unit?

Were you able to get some kind of power logger rigged up for it?

-AC_Hacker

[Xringer]

The big panels (500w) are for heating hot-water, (on sunny days).

I just added on the two little 10w PVs to charge up the batteries,
because they were just sitting in the basement, doing absolutely nothing.

Got those 2 panels for free with my PV order, and the two 12v batteries are left-overs from our cars.
I replace car batteries before they go bad, and recycle the old ones.

My #1 goal is to have some reserve energy to use for lighting etc, during grid failures.

#2, I've been reading up on low cost LED lighting.

http://ecorenovator.org/forum/lighti...ed-lights.html

And I would like to try some LED lighting around the house.
Kinda like extra bright 'night-lights', to allow us to walk around
the house in the evenings, without turning on grid-powered lights.

If it worked well, that would give me some confidence that our grid-fail
back-up power was in good shape.. Just in case..

[Xringer]

Originally Posted by AC_Hacker

Xringer,

Have you been able to determine what your actual typical weekly power is from your unit?

Were you able to get some kind of power logger rigged up for it?

-AC_Hacker

With the weather around here, there doesn't seem to be a typical week..

I've been distracted from my hobby work lately, installing a modern alarm system
for my daughter, plus some carpenter tasks (out of my normal DIYer range).

So, I don't have any power data yet. There is some anecdotal evidence
(extra warm showers on the evenings of sunny days), but no numbers yet.

The good watt readings that I see on cool sunny days, are very encouraging.

I'm still kicking around ideas. One idea, is to install the logger on one panel and x4 the results.
But I need to find some cheap MC4 connectors.. And, add aux power for the meter, to save the daily data.

[Daox]

Don't you have that dc amp hour meter thingy hooked up to the array?