Daytime dome tracking


#1

I use a dome with a solar cell under the shutter which charges the battery for shutter control over they day.

It would be handy it sgp and the end of the sesion would then switch the dome over to a solar tracking routine to aid keeping this battery topped up.

Everythign else in the dome is mains powered.

Any houghts?


#2

I have a similar set-up on a Pulsar Dome. I have been assured that modern solar panels do not actually need direct sunlight - just daylight. In any case you probably use the dome shutter so little (open/close it generally just once every night) that the draw on the battery is minimal - so charging required will also be minimal. In my situation, I am away from the scope/dome for many weeks at a time and I actually unplug the solar panel - stop it trickle charging the battery - until I get back. Battery holds charge and everything resumes without problem. In fact my solar panel points northwest when parked during the day - it still charges the battery plenty for normal use.

Brendan.


#3

Im glad it works for you Brendan.

I however have had multiple instances of a flat battery (at least 5) since installation, what i currently do is before going to work is slew the dome manually over to the rough degree of the sun and it ticks along, since doing this I have not had a problem.

What i want is to not have to remember to do it.


#4

Unsure exactly where you live - but have you tried parking the dome with the solar panel to the south. I can’t imagine you not getting enough solar power out of the charger then. Unsure how old the set-up is or if everything is working or not as it should…but it sounds not if the daylight (not direct sunlight) is not doing a good enough job for you.
Perhaps others have had a similar problem to you and may yet join the thread. Let’s see what others say.


#5

im outside Hereford in the UK, and while i would agree that this should work with the dome just parked (mine is also a pulsar) in reality this has just not been the case for me.

One solution was to set up ascom poth with a telescope simulator and attach the dome and cdc slew it to the sun and track all day, but once again its remembering to do it. a far simpler integrated solution would be great.

the battery and solar panel was upgraded by pulsar too, once i started the whole tracking the sun faff i have not had to recharge once. (thankfully :slight_smile: )


#6

Everything I have read when we put 2 of KW panels on our shop said that there is really not that much difference in total output due to sun pointing panels compared to straight south.

I also have to wonder if the energy used to move the dome would not cut pretty heavily into any small benefit.


#7

The dome rotation is mains powered so it a none issue.


#8

Can you define the park azimuth of your dome? If so just set it to the position you want it during the day and when SGP parks the dome it will rotate into that position. If your dome driver doesn’t allow that directly POTH may emulate that functionality (I can’t recall at the moment).

Thanks,
Jared


#9

I’m a bit surprised that just parking with the solar panel facing South isn’t enough. If it isn’t enough this time of year I doubt that any amount of tracking will be enough in winter.

I wouldn’t use SGP for this because it requires that SGP is running all the time. It is possible to run other programs on a PC.

Whatever you have could use the task scheduler to run each day.

Chris


#10

To determine how many amp-hours a 12v panel provides take it’s rating in watts x .3. So a 100W panel produce about 30 amp hours per day. Panel makers list their MAXIMUM wattage the panel can produce with optimal conditions and that is when the panel is directly facing the sun in both altitude and azimuth.

To get very accurate look at the back of the solar panel or consult specs and find the maximum rated power of the panel in watts. Look also for the maximum power voltage, Vmp, which is in volts. Calculate the current in amps by dividing power in watts by the voltage in volts. Mine are 100W panels with optimal Vmp of 18.9V which for me is 5.29 amps. Even in sunny Florida I need four panels to guarantee my three 120AH battery array is fully charge if I have the telescope running every day of the week simply because while these panels are at tilted at the correct altitude they are fixed due south. In the summer two panels are enough but the winter is different, and we have much clearer skies in the winter here. Most panels max out at about 230W so I think one highly efficient panel, even tracking the sun might be tough to keep the charge full.

Keep in mind your batteries will last longer the lower you drain them. A battery drained to 40% before charging will last a much shorter time then a battery only discharged 10%. When doing this, buying one or two more batteries can make them all last longer.


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