Setting on solar controller.

Anthonyk2010

I just installed a solar panel(vacuum tubes) and left all the setting on the solar controller at there factory setting.
The pump does not switch on untill the panel is 8deg above the lower temp in the cylinder.
It switches off when there is a 4 deg diff.

Has anyone experience in these settings?
is my pump coming on too soon?
Should i let panel get temp increase before pump cuts in?
Should they be different in summer then winter?

quentingargan

Anthonyk2010 wrote: »

I just installed a solar panel(vacuum tubes) and left all the setting on the solar controller at there factory setting.
The pump does not switch on untill the panel is 8deg above the lower temp in the cylinder.
It switches off when there is a 4 deg diff.

Has anyone experience in these settings?
is my pump coming on too soon?
Should i let panel get temp increase before pump cuts in?
Should they be different in summer then winter?

Most controllers come on at a 6 degree difference and off at a 4 degree difference, but 8 is within the range. I wouldn't change this.

However, I wouldn't blithely accept the other defaults. For example, the maximum panel temperature is often 140 by default. This is above the boiling point unless the fluid is above about 2 bar. There are other defaults which you need to understand.

Are your tubes direct flow, or heat pipes? There is another setting for DF ones that needs attention.

If you pm me the make of controller (or a picture of it, as they are often re-badged) if I know the make I might be able to send more info.

homer911

This sounds like something that would be useful to lots of people so please post back and maybe the mods can make a sticky of it...

quentingargan

homer911 wrote: »

This sounds like something that would be useful to lots of people so please post back and maybe the mods can make a sticky of it...

As it happens, Anthonyk2010 has a controller that I haven't worked with. But if there is demand for clarity about controller settings, I would imagine people could post their queries here and someone watching would be familiar with that particular controller. Hope mods would think it OK to name the controller as most of these are sort of generic and are used by several different installers, as long as nobody gets into a rant about the virtue of one controller over another.

PeteHeat

P.M. sent.

Quentin,

Answering questions on an open forum to help might be a good idea however my one reservation goes back to the old saying "A little knowledge can be dangerous"

No disrespect intended, on some threads I have seen people post almost the very same thing that was posted maybe two pages earlier, such action suggests that people do not read the full content.

My concern is the possibility that someone in a hurry uses information in the latest post and it may be completely wrong for their particular application / controller.

Just putting the possibility out for discussion / reaction / consideration.

.

Anthonyk2010

Filtering through the BULL S to find correct info can be mind numbing at times pete, but i understand what your saying a little more patience.

Anthonyk2010

Anthonyk2010 wrote: »

I just installed a solar panel(vacuum tubes) and left all the setting on the solar controller at there factory setting.
The pump does not switch on untill the panel is 8deg above the lower temp in the cylinder.
It switches off when there is a 4 deg diff.

Has anyone experience in these settings?
is my pump coming on too soon?
Should i let panel get temp increase before pump cuts in?
Should they be different in summer then winter?

My solar controller has the same (unchangable) default settings, the only issue is that the cylinder sensor is only reading the temperature in one part of the cylinder.

If you have the sensor at the top you'll only have the pump come on when the panel is hotter than the top of the cylinder and at the bottom you'll have a longer heating period but risk there being periods of time when the top of the cylinder is actually cooled by the solar panel.

Some controllers measure both the top and bottom of the cylinder.

quentingargan

Deleted User wrote: »

My solar controller has the same (unchangable) default settings, the only issue is that the cylinder sensor is only reading the temperature in one part of the cylinder.

If you have the sensor at the top you'll only have the pump come on when the panel is hotter than the top of the cylinder and at the bottom you'll have a longer heating period but risk there being periods of time when the top of the cylinder is actually cooled by the solar panel.

Some controllers measure both the top and bottom of the cylinder.

The problem with having this probe at the top is that the panel spends the whole day operating at a higher temperature, and therefore at less efficiency, particularly for a flatplate. You will also have much higher heat loss in the pipework.

Controllers have come down in price quite a bit, and I can't imagine many of these more basic controllers being used. But if you have one, the probe should be in the area of the solar coil. You can get a fitting that enables the probe to go in on a T into the pipe going into the coil if there isn't a place on the cylinder.