Roll off or Roll away

[MattJenko]

Hi All,

I now have the ability and chance to create myself a permanent installation after years of setting up and tearing down. I have a section of garden which is not too tree obscured and while it is far enough away to be dark, it is also too far away for electricity, so thinking of solar powered and battery operated. However, my big question is roll off or roll away. Space is not a huge concern and I am planning on 2 piers, or a pier and space for a heavy tripod based setup. In a rollaway, everything is rather straight forward it seems and all the panels on the roof/batteries etc simply move with the shed, so nothing complex for a DIY novice, which I most assuredly am.

What advantages does a roll off roof give over a full roll away setup, and is wind protection really that important and done well by a roll off roof anyway?

Cheers

Matt

[IanL]

Hi Matt,

I guess you and Mr Bricolage are about to become close acquaintances then! First thing to resolve is the required dimensions of the beast. Two scopes suggests a relatively large structure, plus would you need a warm room or similar for the kit? Are you going to just do imaging, in which case you can take the minimal size approach like I did, or do you want to observe from it too?

It would be a good idea to figure all that out and then mock up the size using canes, string or whatever and put the kit inside it on tripods so you get a feel for what you really need.  I found that helpful when planning and siting my little imaging box as the paper plans didn't convey any real sense of what I would end up with.

If it ends up being fairly large, I don't think there is going to be much difference in terms of engineering/structural challenge either way. Small roll-aways seem to be easy to make with a basic shed and a bit of modification. Making a shed strong enough to be roll-away if it is 3 or 4 metres per side is (in my estimation) actually going to be harder than modifying just the roof to roll-off. You've got much more weight, longer uprights to flex, etc.

If it is minimal size, then a roll-away only needs to be big enough to cover the scopes and tripods, and you don't need to worry about operator space. Either way you're going to have to build a chunky frame in to the existing shed, or go for a complete custom build from the ground up, in which case why not have a roll-off roof anyway?

Advantages of a roll-off roof are more shelter from the wind and any stray light (may not be a problem for you), plus for mine I put in a double-skinned wall with insulation which seems pretty weather and condensation proof. The whole installation can be more secure, as you can build it more substantially whereas with a roll-away you're probably going to have to reduce weight to make it workable.

I wouldn't worry about the DIY side of things, it's largely just a matter of planning first based on other people's write-ups plus a bit of research on basic woodworking, etc. After that I found it was mostly just common sense and not rushing in to a job and thinking it through. Don't underestimate the time needed, I must have put in about three days a week for most of three/four months to finish mine. Second time round I could probably do it in half the time, but it is a learning process.

Happy to pop over and provide a bit of consultancy when you need it

 

 

[pete_l]

The advantage of roll-away is that you can target stuff closer to the horizon. However, you may quickly find that those targets are not as good as it would appear. That can be due to light pollution (worse closer to the horizon) or simply due to the much larger air-mass that starlight has to travel through, once you get below 10° or so.

The disadvantage is that your equipment has no shielding from wind. It also requires more effort to move the extra weight of the walls and one end, in addition to the roof.

Choosing a judicious height of wall and then just rolling away the roof would seem to be the optimal solution. Although the extra complication (and eyesores) of high-level tracks and their supports might work against that.

[Starlight 1]

38 minutes ago, MattJenko said:

solar powered and battery operated

My South side of the roof is all solar panels . and 10 battery in a box out side . I pull 150 amp a hour in full Sun and have a long cable running inside roof to the box were all the Solar panels plug in so it move with the roof , good for doing diy as well save running about with leads to the house.  roof still move easy .

[MattJenko]

Sounds very doable then with both options - 10 Batteries? What power are they and did you calculate it or just go BIG? I was thinking heavy duty 100Ah+ ones and possibly 3 of them for a 2 pier setup according to my very crude napkin calcs and an equivalent 3 175W panels...

[Starlight 1]

You have to go on line to get  calculate  right . and the main unit shut down when batterys are full . just 10 old car battery any size will do it still only 12 v then you use a unit to take the 12v  into 240v , so I just use all plugs as 240v  not the best way turning 12v to 240v and bringing back down to 12v again , but going out the dark with your laptop its just unplug and plug back in up the garden with out thinking is this plug on 12 or 240.

[MattJenko]

Agreed on getting the calcs right, my initial thoughts come from a caravan power consumption online calculator :). You have made my original dilemma harder though by removing what I thought would be an additional complication in having the roof only move though...

[Starlight 1]

For me more battery last longer, I have a unit as well to send power back to the house just plug it in at the wall plug ,so if I am not going out I can still use the power save that day.

[Starlight 1]

Plus no one will every think of a shed roof full of solar panels as a astro shed.