mtm tracker whit relay
 

I will interpret your silence so that you do not want to help others

I had problems connecting to the server yesterday..


Anyways, MTM is a one man company and the owner asked me not
give the circuit diagram to anyone. He wants to sell products.
(He gives board owners a schematic diagram for their own use. Not to be shared).
Giving someone a picture of the bottom of the board, amounts to the same thing.


The circuit posted above using an LM339, is almost identical to the MTM board.
Schematic for Solar Collector Sun Tracking, Richard Gideon shares solar technology, Phoenix Turbine Builders Club Developer of the Month
But it has controls that might allow it to be set up, so it doesn't chatter the relays to death, like the MTM design.

Take a look at it.. It looks like a better design to me.
I just don't like using relays for this type of application.
Without a really good controller design, the relays won't last.

Dump loads
 

Guys,
Before I got the first intertie I had thought about a dump load with a transfer switch. My thinking has changed now. First my batteries are strictly for back up if the grid goes down. Why use batteries when my intertie/off grid system sends excess power (after all my dedicated breakers are serviced) back to the grid. If I want to run a small heater all I have to do is plug it in. My system will power it and if there's excess send it back to the grid. No relays, no dump resistors, etc. I think this intertie/ off grid setup is the best way to go, you never lose a watt of power, if you don't use it you sell it and your batteries last a really long time.

Xringer,
Looks like a neat project! How many modules are you running on that dish, what's the square footage?

Rob

Just noticed this thread.
Thought at first you were going to coat the surface of the dish with aluminum foil or surplus mirror pieces and build a concentrator, then saw you using it just for one-axis tracking.

If you decide to try a concentrator and 2 axis tracking, the link below is a unit I helped build that could give you some information of the thermal aspects of keeping a concentrator cool.

http://www.stretchedlensarray.com/Papers/SPS600V.pdf

I see where people are using Sterling Engines off concentrators now at some decent efficiencies.
Rob

There are four 125w panels mounted on it. Don't know the sq feet..
It keeps my battery bank charged and helps heat my DHW tank..

The reason I wanted to convert my Radio Astronomy dish to solar tracking, (see plot of galactic core).
was mostly just because I had this nice polar TVRO mount.
Didn't want to scrap it. It's got a certain cool factor, if you are a Ham..

2-axis for solar tracking is pretty much a waste of money.
Since you need to inspect the mount every month or two anyways,
why not take an extra 35 seconds to tweak the elevation?
You don't have to take my word for it, just ask people who have been using trackers for a few years.

Since the price of PV is dropping nicely, there is really no need to track the sun.
Just add more PV for the same money/effort and get the same end result.
The best part is no moving parts. :) Chance of failure drops to near zero.
Not a lot of maintenance needed on a fixed mount PV array..
If it's on the roof, you might want to try pulling the snow off..
I did that when I had solar hotwater on the roof, many years ago.

Xringer,
Yes, I would say modules on a roof - not the best but since I got the system for free and had a time limitation to get it in, a roof mount system was the best solution for me. I've been up clearing snow. It takes about 20 minutes and gets me out in the winter which is important. The front modules just about clean themselves especially at the winter angles my modules sit at.

I think if I had 4 modules I would probably use a tracker but with 8 modules and over 100 sq/ft of area the logistics got very complex very fast.

Ditto on the dual tracking system, azimuth just isn't that important.

Rob