Shed power

[Ags]

I am looking to power my garden shed, which has become the home for my equipment due to dusty building activities in my habitation. I am looking at this little device, it will only have to keep a couple of batteries charged by usb, which will in turn power telescopes and a light in the shed. Am I on the right track or are there better options?

https://www.amazon.nl/dp/B08KZF2FX4?ref_=cm_sw_r_mwn_dp_GGXAE56TAZJDSP9VGYQB

[vlaiv]

5 minutes ago, Ags said:

Am I on the right track or are there better options?

Best to calculate your actual power needs and go from there.

Winter is behind us, so using solar panels is feasible, but if you plan on extending usage into next winter - do give this a serious thought.

I have solar array on my house - 10.6KW of power and average daily power production in "peak" (or rather trough if we think in term of waves / yearly cycle of power output) winter months was less than 10KWh.

By that analogy - you'd get 120Wh from 120W panel in winter time or about 10Ah per day (of course, this is average, there will be days with very low production).

I expect summer to be better by factor of at least x6 if not x8. I'm now at x4 compared to December / January, or about 40KWh per day.

[Greymouser]

Why not power it from the mains? I intend to do so for my shed. I was initially going to run the cable through the ground, armour it to be safe and get an electrician to connect to the house. However, the price put me of, have you seen the price of armoured cable?! Never mind the rest. Now I intend to get an extension cable, disconnect the circuit breaker, then run it through plastic conduit above ground, to protect the wire from weather and UV, then drill a little hole in the door frame put the wire through, seal the hole with silicon, re attach the circuit breaker and plug in the socket by the back door. Job done. I hope. 

Seems to me a solar panel will not be efficient enough and it will deteriorate.

[Ags]

It would be very awkward to run a cable to our shed, hence looking at solar. The rate at which I use batteries strongly suggests the solar cells would be sufficient. The concerns I have are around how durable this would be.

[Mandy D]

4 minutes ago, Ags said:

It would be very awkward to run a cable to our shed, hence looking at solar. The rate at which I use batteries strongly suggests the solar cells would be sufficient. The concerns I have are around how durable this would be.

Why would it not be a durable solution? Solar PV installations have lives in excess of ten years. For sizing, take Vlad's advice. You always size for winter insolation. I guess you can cope with the days when you get no Sun, as you probably won't be observing on those nights, either, plus you are likely to get some on other days when not observing.

[Ags]

@Mandy D not so worried about the photoelectric deterioration of the cells, I'm more concerned about mechanical wear from wind and rain (snow seems rather unlikely given the last few winters).

Does anyone know why they say to connect the battery before the cells? What if I just want to use the USB ports?

[Carbon Brush]

In my experience small panels sold for retail, think in terms of obtaining 10% of the claimed power output when averaged over several days.
Yes the panel performance has improved in recent years. But the claimed power often is more than reality!
The figures claimed are often correct for a desert near the equator, at noon, with the panel correctly angled.
With a Northern Europe solar intensity, fixed panel angle, clouds, etc.......

The reduction in power is quite significant as soon as a panel goes off perpendicular to the sun.
If it generates 100% when perpendicular to the sun, it drops to 50% for a 30deg solar angle - whether in alt or az.
In other words, if the panel could produce 120W at noon, it would drop to 60W by 3pm.
Actually the reality is worse due the panel going out in both alt and az.

If you look at panels for professional use, the manufacturers make more realistic power claims and recommend mounting angles based on latitude.

My feeling is that you are going to be using scopes more in winter, when the days are shorter, the sun is lower and there is more cloud.
If you think of Netherlands being about 53deg N, the noon sun is at this angle at the equinoxes. At the winter solstice is only at 20deg.

It might be a lot easier (and cheaper) to bring a 12V battery from the house.

HTH, David.

 

[Ags]

@Carbon Brush you have persuaded me!

[vlaiv]

11 hours ago, Carbon Brush said:

In other words, if the panel could produce 120W at noon, it would drop to 60W by 3pm.

It really depends on panel in question.

Theoretically, without impact of atmosphere - at 3pm, which would be at 45 degrees, one would expect drop to ~71% of nominal power ( cos(45 degrees) ), but given that air mass is also increased - it is a bit less for "conventional" panels. However, recent panels have significant IR sensitivity and air mass does not have as high impact as one might think.

here is a graph for one of days that shows nice curve outline (although there were some intermittent clouds all over the place). Peak intensity around 12 o'clock was at about 7500W while envelope curve at around 15h is at ~5700W.

Now, that is a bit more then theoretical max of 71% - but that is because above is not output from single flat panel, but rather 3 groups of panels - one facing east, one facing west and one facing south (tried to optimize roof surface, since I don't have enough south facing roof for the lot), so I don't get clear peak at 12h - but somewhat smaller value (my array is nominally 10.6K but I'm yet to see peak output higher than about 8000W).

 

[Nik271]

Have you considered a wind generator? There are some small propellers of the type usually installed on canal boats, rated at about 200W which deliver 12 Volts DC current to a battery. Wind is generally a lot more reliable than sun in northern Europe in winter.

Edited May 10, 2023 by Nik271
corrected the maximal power output

[vlaiv]

3 minutes ago, Nik271 said:

Have you considered a wind generator? There are some small propellers of the type usually installed on canal boats, rated at about 500W which deliver 12 Volts DC current to a battery. Wind is generally a lot more reliable than sun in northern Europe in winter.

Actually - it is the combination of the two that should perform the best, but it might be an overkill for such application?

I've seen 3d printed generators that are grab'n'go type - really interesting.

https://hackaday.io/project/185070-3d-printed-portable-wind-turbine

[Carbon Brush]

I have trialled wind generators in other applications. Again retail vs industrial gives a huge difference.

An absolute failure was a generator bought from Amazon, along with the charge controller/dynamic brake.
Supposedly for putting near your house, on a boat, caravan, etc.
It was definite chocolate fireguard stuff. You needed a gale to make it turn.
The controller ate the battery power when it was idle. The (fail safe) brake relay being energised all the time.
The cheapie chinese manufacturer had used low cost automotive relays - where power consumption takes a definite second to cost.
He had not even though about reducing coil current after pull in. Definite kitchen table standard bodge design.
In the end the whole lot was junked.

Now this is a very good product I have used.
https://www.leadingedgepower.com/le-v50-extreme-vertical-axis-wind-turbine-12-24-48v-1486339.html
 

Suffice it to say, the Leading Edge turbine is fit and forget for years. In my application it is sitting on top of a power station cooling tower.
It won't be accessed ever. Brought back to ground only when the tower is demolished along with the rest of the power station.
But not hobby pricing😁

HTH, David.

 

[maw lod qan]

I kicked the solar panel tire when I powered my observatory. 

Finally just ran power from my mains. 

Thankfully I already had power 1/3 of the way to an outlet for when I needed it near where I parked.

I used wire that was UV and direct burial rated. Also have a car battery hooked to a trickle charger for when I might loose power.

[Ags]

I have been thinking on and off about getting one of these. 

https://www.amazon.nl/-/en/Bresser-Station-telescopes-electronic-connection/dp/B07VCFQLYG/ref=d_pd_sbs_sccl_4_3/259-9965323-5265014?pd_rd_w=yoOtg&content-id=amzn1.sym.c41a8b3f-0a24-4a0a-bc5f-4f6f6c01ae9c&pf_rd_p=c41a8b3f-0a24-4a0a-bc5f-4f6f6c01ae9c&pf_rd_r=AJTF8X9KPVBDTC3NMKPZ&pd_rd_wg=U8ObR&pd_rd_r=c957c54d-f690-4c1c-b909-a0eea7a1c377&pd_rd_i=B07VCFQLYG&th=1

[cajen2]

Looks good. On my page it says "unavailable". I have something very similar by SinKeu:

https://www.amazon.co.uk/gp/aw/d/B09MZ736CZ?psc=1&ref=ppx_pop_mob_b_asin_title

It was on offer at £30 cheaper. I have to say it seems excellent. I've used it to power my AZGTIX mount over several short observations and it's still showing full battery.

[david_taurus83]

Really, how difficult is it to run a mains cable from house to shed? I have (previous owner installed) armoured cable running from 3 pin plug in house to shed less than 20m away. It's pinned to the bottom of our garden fence so it doesn't look intrusive. I installed a new RCD outdoor socket in shed when we moved in. Powers my astro pier 24/7 and lights and power tools in the shed.

[Ags]

@david_taurus83 this is only my temporary shed so I don't want to lay a cable that won't be needed after a few months. Also I am happy to have a reason to upgrade my battery options, which obviously have nonshed applications too. I may very well run a cable to the official astroshed when it goes up next year, rather than getting a solar solution that could have been relocated to the astroshed.

[scotty38]

11 hours ago, Ags said:

@david_taurus83 this is only my temporary shed so I don't want to lay a cable that won't be needed after a few months. Also I am happy to have a reason to upgrade my battery options, which obviously have nonshed applications too. I may very well run a cable to the official astroshed when it goes up next year, rather than getting a solar solution that could have been relocated to the astroshed.

How far is it to the shed from the nearest power socket? I realise you said you don't want to lay anything yet but even an extension that you roll out each time would eliminate any/all issues re solar, battery etc etc.

[vlaiv]

Here is a silly idea.

Why don't you get two sets of batteries? Get light weight ones. I'm guessing that won't be much more money than battery + solar panel combo.

Keep one battery in observatory and the other in the house. One in the house will be recharged until next astronomy cycle

When you have astronomy night - bring spare battery with you and when you are finished - just swap them around. Leave fully charged battery for next session and bring used up one with you for recharging?

[Ags]

Yes I have been thinking of two batteries too!

[cajen2]

Most of these power tanks can be charged from relatively small solar panels. Let it charge during the day and you'll have plenty of charge for the night.

[Guest]

I borrowed a solar power setup just to see how long it would take to charge something up.  Yeah it works .... Sort of.  It isnt really practical if you live in cloud covered Ohio.