General advice re backup lighting idea and running servers via solar/battery

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ptolemy2

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Greetings all

I have absolutely no experience and very little knowledge on the subject of solar-cum-battery power so I ask your forbearance if some of my questions are stupid.

I have had 2 ideas regarding solutions to the problems caused by load shedding blackouts. But I'm not sure of the technical feasibility of either.

First the relatively simple solution, I hope.

I would like to build some sort of emergency lighting system using 3W 20LED light pads. The sort they sell to replace your car's dome light. I'm thinking of something that would come on immediately the power fails except during the day when a day/night switch would keep the 12V DC circuit from closing. I've seen fairly simple emergency lighting circuits online, using onboard nicad batteries. Each light has it's own battery. The batteries are charged from the grid while the power is on.

My idea is slightly different: would it be feasible to build a secondary 12V DC lighting circuit running off a single 12V 90Ah deep cycle calcium battery - I just happen to have one. The idea is that the battery would be on constant charge while the power is on, but as soon as the power to the charger fails, a relay closes the 12 V circuit and turns all the lights on in all the rooms immediately; except when it's daylight.

I'm thinking that I would use fairly heavy Surfex cable - rated up to 34 Amps, to overcome the problem of low voltage high amps and heat and fire and disaster. At least that's my inexpert thinking.

There would be about 8 individual lights "fittings", 2 in the kitchen and 1 each in other rooms. No cable should be longer than about 2M. If I'm not mistaken the whole circuit is no more than 2 amps but I don't know all the implication of cable length and resistance etc. There would be a need for a fuse I imagine.

The second question is: How feasible is it to run 2 Dell rack mounted servers 24 hours a day, without interruption, completely off the grid; with some sort of solar/battery/inverter solution. Shutting them down every time the UPS starts beeping is very disruptive and real pain.

The power supplies are rated 375W and 450W respectively, but I doubt they are drawing anywhere near that at any time. One would also have to add in the router and switch and WiFi access point. All fairly low wattage. BTW, how can I find out exactly the power consumption of the servers?

Any thoughts, ideas, technical suggestions or dire warnings gratefully sought and accepted.

Thanks in advance.

Regards

Harry.
 
I purchased a watt meter from builders and measured the consumption from my rack.

Proceeded to hook up a 1000W pure sine wave inverter with 2 102Ah batteries.
Keeps the server, router, adsl and wifi up for around 18 hours.
Also hooked up 2 external 10W led floodlights for external lighting and a day/night switch.

My PC is also on this same inverter, but if using that my time drops to just under 4 hours which just sees me through a day time load shed.

Also going to work on internal lighting next. But want to hook into the DB board (all rooms are led). For now we just have emergency lights dotted around and they do the job.
 
Thanks Mike

That sounds like it will do the job. Are you running the server off the inverter full time and charging the batteries from the grid?

Does that suggest then that if a solar panel or panels, can keep the batteries fully charged, that the server could in fact be off the grid?

Cheers.

Harry.

Mike Smit said:
I purchased a watt meter from builders and measured the consumption from my rack.

Proceeded to hook up a 1000W pure sine wave inverter with 2 102Ah batteries.
Keeps the server, router, adsl and wifi up for around 18 hours.
Also hooked up 2 external 10W led floodlights for external lighting and a day/night switch.

My PC is also on this same inverter, but if using that my time drops to just under 4 hours which just sees me through a day time load shed.

Also going to work on internal lighting next. But want to hook into the DB board (all rooms are led). For now we just have emergency lights dotted around and they do the job.
Click to expand...
 
ptolemy2 said:
Thanks Mike

That sounds like it will do the job. Are you running the server off the inverter full time and charging the batteries from the grid?

Does that suggest then that if a solar panel or panels, can keep the batteries fully charged, that the server could in fact be off the grid?

Cheers.

Harry.
Click to expand...
Yes, charges off the grid. I am looking at solar options but not taken any real steps yet. This currently works quite well for me and batteries are fully charged between load sheds.
But ye - if putting some panels on then this setup will be off grid.
My solar plans will probably kick in after I have the lights done.
Also got an inverter and batteries on the bedroom TV, house wifi, switch and Roku. Need 2 more batteries (got the inverter) and will also hook up the lounge TV. These are the current plans before properly doing the lighting.

When all the above is done, I will probably do solar. Main focus was to have battery backup.

Also got a gas hob and solar geyser installed which helps a LOT with the current rate of load shedding.
 
Re: my plan to use solar panels to maintain 2 x 105 AH Deep Cycle lead-acid batteries charged ..

Is there a calculator available to determine the direction, and angle, that the panels should be mounted at to ensure optimal possible exposure to the sun at any given Lat / Lon location?

EDIT: I found this website but it's beyond my understanding

http://www.alternative-energy-tutorials.com/solar-power/solar-panel-orientation.html
 
Last edited:
atomcrusher said:
Re: my plan to use solar panels to maintain 2 x 105 AH Deep Cycle lead-acid batteries charged ..

Is there a calculator available to determine the direction, and angle, that the panels should be mounted at to ensure optimal possible exposure to the sun at any given Lat / Lon location?

EDIT: I found this website but it's beyond my understanding

http://www.alternative-energy-tutorials.com/solar-power/solar-panel-orientation.html
Click to expand...

Pro setups have the panels track the sun. If yours will be in a fixed position then it's best to position it optimally for mid winter imo.
 
biometrics said:
If yours will be in a fixed position then it's best to position it optimally for mid winter imo.
Click to expand...

Good tip - thanks. I had thought of pointing panels due north, but I guess that both latitude & longitude are important factors to consider when setting up any solar panel. I'll Google for info re: correct placement per LAT / LON location

EDIT: Here's an interesting article re: orientation & pitch of solar panels. It refers to the Northern Hemisphere, but the principals can be used to calculate the same info for the SH

http://solarpowerjoe.com/selecting-the-proper-orientation-and-pitch-for-your-solar-panels/
 
Last edited:
Greetings all

Since my last posts initiating this thread, I have been working on - i.e. thinking about - my emergency lighting circuit. And I've accumulated a few bits and pieces to add to the stuff I had lying around the workshop and I'm now ready to put it all together. There are still some things I'm not sure of so I would appreciate any and all comments and advice.

In short, I want to set up a 12 volt DC circuit to drive some LED light pads in a number of rooms in the house. They will come on automatically via an AC/DC relay which closes the 12V circuit when the AC power fails; unless it is still light outside. There will be a day/night switch in the circuit.

These are the lights I'm planning to use:

55_B3540020X50TS.jpg_zoom.jpg


I've created a diagram to help me visualise the whole project. Apologies to the purists, it's not a proper symbolic circuit diagram but more of a working drawing. It is in PDF format. You can download it here: https://www.dropbox.com/s/h4zw75lqc94zznw/A1-Print.pdf?dl=0

I wanted to see if I could get this going with minimal expense and using 2 things I already had.

1. The Delphi Freedom 12V calcium battery, which I took off somebody who was replacing his industrial backup setup. They replace them every few years.

2. A crappy little float charger I bought from Dixon Batteries to keep my motorcycle battery from dying over the winter.

I know nothing about the suitability of either of the above for the job at hand but I will say this: I ran 2 security cameras off the combo for about 6 months and they work flawlessly for that time. The battery's little indicator window was always showing green and the charger was never even warm. Everything was connected via approx. 30M of Cat 5 cable.

Please have a look at the diagram and let me know if there are any glaring errors before I go ahead.

There are one or two things that worry me a bit because I don't know much about them.

1. I don't know enough about voltage drop caused by cable length.
2. I'm a bit concerned about the wires overheating and setting my roof alight. How do I calculate what thickness of wire I need. Each light is 3W and there will be around 6 of them possibly 8, if all looks like it's working OK.

On both points, my thoughts are that it probably isn't too serious but I would appreciate any comments and dire warnings of imminent catastrophe. Having said that, I have a 12 volt security camera power supply driving 8 cameras around the property, with the furthest 2 cameras 50M and 60M away, respectively. They are connected via the combo co-ax and power cable. My LED lighting cables will only be a few meters long

So that's the plan.

Look forward to wise council from the many tech gurus in this forum.

Thanks

Harry
 
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I was under the impression that a DC system house-wide results in heavy losses...will leave that up to someone more knowledgeable though.

Also...not sure what the effect on COC compliance & insurance would be with a DC system...you might want to check that out as well.
 
Have you tested the LEDs already? For decent lighting, you'll need about 4 of those for a normal bedroom. What light fittings do you currently have? I'd rather add or swop out some existing downlights to GR16 12V LED. It will look much neater?

At 3W per LED, you'll be drawing 0.25 A (250 mA) per LED. That's quite a little. So you won't have much problem with voltage drops.

Calculate the total current that you will draw, then make sure that the cables can carry much more than that. Then also make sure you fuse is smaller - that way, you fuse will blow before the cables get hot/melt. For eg. 10 LEDs = 30W => 30/12 = 2.5 A. Normal 1.5mm "twin and earth" wiring used for 220V lighting in houses can easily handle 10 A (that is why your circuit breakers for lights are normally 10 A. Extension leads are also normally 1.5mm - sothat cable will also work. Then uses a fuse that is less than 10 A - say 5A. Then you'll be very safe.

I wouldn't connect the setup directly to the DB - rather just run your junction box from a normal plug. There is no need to touch the DB.

On a side note - it is called a busbar not buzzbar :)
 
HavocXphere said:
I was under the impression that a DC system house-wide results in heavy losses...will leave that up to someone more knowledgeable though.

Also...not sure what the effect on COC compliance & insurance would be with a DC system...you might want to check that out as well.
Click to expand...

I've had a few 12V DC LEDs and halogens... I took them out due to compliance issues. It's a massive grey area and almost everyone has their own opinion on it. The leading consensus on the matter as far as I understand, is that your supply still needs to be 220VAC, and each light needs it's own dedicated transformer.

Given the price, it becomes cheaper to just install 220V LEDs really. Hence, now my entire house runs on 2W LED down lights.
 
greg_SA said:
I wouldn't connect the setup directly to the DB - rather just run your junction box from a normal plug. There is no need to touch the DB.
Click to expand...

FYI - If you can't remove the appliance, it will form part of COC. i.e. a light attached to the ceiling will form part of COC regardless of where it is supplied from, but a TV, Fridge, etc. won't form part of a COC because it can be removed.

So if you have lights attached to the ceiling, fed from a wall plug socket, that will be a immediate COC failure IMHO.
 
Ah, I understand :) I wasn't expecting the original poster is consider a COC for this DIY setup.
 
Thanks for all the comments. You guys are certainly early birds.

At some point in the distant past, I used to know the word was "busbar" but then "buzzbar" got into my head from somewhere. Old age is creeping up on me. Thanks greg_SA, and for the calculation advice.

You confirm what I was thinking. I might use up to 10 of these LED's but more likely only 8. I was thinking of using normal Surfex cable, which is rated around 20A, even up to 34A, and is quite robust, being armoured.

As for the quality and amount of light the LED's will provide, they will not replace the normal lighting completely; just stop me from walking into walls and having to scramble around looking for torches and lighting candles. They are quite bright though and I have tested them by Pressticking one to the lightfitting. I'm happy with the result. A 60W incandesent lamp provides about 450 lumens, the pad provides around 300+.

The plan is to put them inside the light fitting, which are all frosted glass cheese fittings, so they won't be visible. I should be able to run the DC wires down next to the AC wires from the ceiling. Still have to figure that out. All my globes are energy saver flourescents, so there shouldn't be a problem with heat melting the LED's.

I just happen to have an unused 5A breaker, which used to be used for a door bell, available and it is right there, next to the whole planned installation. Frankly it's easier to install a new plug from there, than to run an extension cable from one of the kitchen plugs, which are overloaded already. But I take your point thanks.

You are right I'm not worried about compliance issues. This is a commercial building which I own and I live in the flat upstairs. I am master of all I survey.

But on the subject of COC, savage's comment, one can get emergency lights which have their own built-in (mostly) ni-cad batteries and also come on when the power fails. But they are quite expensive, close to a grand and some more than a K per fitting. And you need one for each room. I checked them out in a lighting store. The light is quite horrible and I think less bright than my plan. No doubt there are better and worse models, I suppose.

HavocXphere, after your comment I did a bit of Googling and came up with these links.

https://www.greentechmedia.com/articles/read/a-current-in-every-ceiling-5278
http://www.greentechmedia.com/artic...he-Use-of-DC-Power-for-the-Energy-Smart-Home#

It would probably take quite a bit of retrofitting to do it properly, but the idea appeals to me. If one could use a bit of solar, one could be off the grid for all one's lighting and perhaps a few other essentials. It would make us more independent and save some money. When I started this thread I also asked about running my 2 Dell servers off an inverter. I'd like them and my ADSL router and LAN hardware off the grid completely if possible. But I think I should start a new thread for that.

Thanks

Regards

Harry
 
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