Jump to content

Recommended Posts

Hi 

I have read with great interest and excitement the many threads in this particular section as it seems I am not alone! 

First and foremost I must geniunely thank all of the contriobutors for taking the time to respond! I have already learned so many new things and gotchas to be aware of! Unfortunately, despite my newly acquired knowledge and best efforts, I still have a few questions about building a home UPS which I hope someone would be kind enough to help with!

If I were to define what I am looking to achieve it would be: "I would like to build a small integrated home UPS to automatically power household lights and small office equipment for the duration of a 2 hour load shedding for a modest price"

From previous threads I will try to include as much information as possible, if I have left anything out I apologise in advance let me know and will correct.

Our house consumes an average of 18KW per day. From my monitoring/calculations this can be broken down as follows:

  • 6KW - Geyser
  • 6KW - Pool Pump
  • 6KW - Daily Usage

In terms of the devices that I would like to power during load shedding these are (attached is a calculation page):

  • 3.2w LED Lights - Inside House 
  • 10w LED Flodlights - Outside House 
  • CCTV Camera Power Supplies x 2
  • CCTV DVR & HDD
  • Wifi Routers 
  • Fibre Router
  • Laptops (batteries no longer hold charge)
  • Cell phone charging

The above equates to the full lights circuit and two plugs.

In terms of assumptions:

  • Safety is of paramount impotance/non-negotiable and by virtue of this a "suicide plug connection" is out(?)
  • Cost is a limiting factor, budget is R10 000 - R15 000.
  • While I do have full solar aspirations, the reality is that this will not be happening any time soon so building a fit for purpose UPS system is priority. That said if having a panel or two available to assist in charging the batteries makes sense for a little extra cost than more than happy to be guided on this.
  • Due to the need to have the house/external lights and a couple of selected plug points powered; integration into the household wiring circuit is (I think) required (this is one area I am stuck on but more about this later)
  • I would like the switching and charging  to be automatic
  • I am completely open to any suggestions 

From the reading I have done through the threads, the following has become apparent:

  • Buy the very best inverter you can afford; Anecdotal evidence suggests that Victron seems to win everytime despite the inital cost (I was leaning towards a Mercer/Axpert but the evidence seems to suggest rather dont?)
  • To integrate to my home wiring the inverter must be able to blend with Eskom
  • A CoC is required
  • A simple sytem can be DIY'ed with the final connection installed by an Electrician to help save on cost
  • Dont be fixed on Lithium as I am not going full solar within lets say 5 years

The questions I have are as follows:

  • I have attached photos of my DB Board but would really like opinons on the possibility of splitting my existing board into high and low load zones. That said, if this means a difficult and messy install (or just not worth it) then for myself it is non-starter as our home electrics work without fault.
  • Other things that have been mentioned is that if I were to use a new DB board (or repurpose the exisitng) to create a load low zone (apologies for incorrect terminology) this may mean rewiring those circuits as joins are not preferred (?). Is this true?
  • Are there any ideas on the cost for this type of work (just ballpark).
  • In terms of the DB board side of things is this something that a normal electrician can do or would it be better to use a electrician who would do the entire install - a comment was made on a prevous thread that one must be wary of using "just anybody" as when it comes to troubleshooting this can be problematic
  • In terms of integrating the UPS Inverter to the home circuit, how is this nornally achieved? I have read a couple of threads with differring solutions, from "blue caravan plug" to full integration with load splitting. In my head the caravan plug solution seems to be the most practical as potentially a generator or replacement UPS could simply be "plugged in" with no other alterations?
  • Ideally, I would prefer an automatic switch over. What I mean by this, I can only assimilate to my existing office setup, I have a couple of small GiCom UPS's that power my routers, as you can imagine they are plugged into the mains and react so quickly to a power failure that the devices connected dont even flutter on a power failure, when there is power they maintain the batteries.
  • What would a recommended solution be?
  • Using the existing lights is my biggest challenge "plugged in devices" are relatively easy, is there a solve for just this?

Thanks in advance!

Cheers

David

1612792673817.jpg

1612792673829.jpg

Usage.jpg

Link to post
Share on other sites

On mobile so limited right now but the sunsynk 5kw inverter is a very good option. 

It is not as costly as a victron setup, it's one piece of equipment that does everything and can be scaled up. 

DB should not be that difficult to split as most circuts would already be simple to split. Lights would not share the same circut as plugs and the geyser should be in its own in any case. It's just a matter of identifying the breakers. You do seem to have enough open spaces available to split it within the existing DB

Link to post
Share on other sites
24 minutes ago, OceanWanderer said:

Hi Achmat

Thank you for your post, much appreciated! 

David

With the sunsynk you could leave the breakers at the bottom for geyser and pool pump and move the rest of the breakers to the load output of the inverter. The sunsynk also has an aux output where you could connect the geyser and pool pump so you will have the option to provide them with limited power during load shedding 

Diagram of how to split them with the sunsynk. This could just be an internal split on the same DB instead of two different DBs. 

Depending on the loads and available electricity sources, it will blend from solar first then either batteries or grid depending on settings. 

Screenshot_20210208-225958_Acrobat for Samsung.jpg

Edited by Achmat
Link to post
Share on other sites

It looks like you have quite a bit of space in your DB and in my opinion and based on your requirements I would suggest installing a manual change over switch and splitting your DB into two parts, the one being essential with those circuits you mentioned and the rest stay on Eskom.

Regarding joints on the wiring it is allowed and is normally the most cost effective way of doing things as long as joints are made in the DB or in junction boxes that is accessible.

Then the essential wiring in some cases will need some modifications or even installing a new circuit whatever is the easiest. 

By doing like the above your installation will basically be ready to hook up to a UPS, inverter or generator.

 

Link to post
Share on other sites

In your price range the pure sine wave inverters may not be an option.

 

Before I had solar installed I wired a R10k Ellies UPS trolly into my DB the two deep cycle model. I added a few red UPS plugs at critical locations for the Internet, my study and my wifes study. Our cinema was also powered by the red plugs to protect the projector. And lastly all the lights were also powered by the UPS. 

On the last day of the solar install while the last bits were being wired in we were without power for 5 hours. Both my wife and I worked the whole time on the UPS. In the past it got us through load shedding many times, often without us even noticing the power is off, except if someone tried to power a kettle.

This setup, with the wiring of the UPS plugs and DB board should end up costing less than R15k, including UPS, wiring and the electricians cost. If you want anything more than this you might want to consider uadding a zero to your budget and adding backup power for the whole house (excepting of course the geyser and any electric stoves and ovens you might have.

Link to post
Share on other sites
On 2021/02/15 at 1:03 PM, Paul Greeff said:

In your price range the pure sine wave inverters may not be an option.

 

Before I had solar installed I wired a R10k Ellies UPS trolly into my DB the two deep cycle model. I added a few red UPS plugs at critical locations for the Internet, my study and my wifes study. Our cinema was also powered by the red plugs to protect the projector. And lastly all the lights were also powered by the UPS. 

On the last day of the solar install while the last bits were being wired in we were without power for 5 hours. Both my wife and I worked the whole time on the UPS. In the past it got us through load shedding many times, often without us even noticing the power is off, except if someone tried to power a kettle.

This setup, with the wiring of the UPS plugs and DB board should end up costing less than R15k, including UPS, wiring and the electricians cost. If you want anything more than this you might want to consider uadding a zero to your budget and adding backup power for the whole house (excepting of course the geyser and any electric stoves and ovens you might have.

How long did you use your Ellies UPS before moving on to solar?

Link to post
Share on other sites

Having tried this type of UPS solution myself for a few years I became disillusioned with it. This was due to the cost of the deep cycle batteries that need to be replaced every 2 to 3 years at considerable expense. You didn't have this system long enough to experience this disappointment.

I think that it's strategically better to implement a solar PV inverter instead. Sure it's going to cost more but the solution is not a temporary one. If cost is an issue one can build your system progressively starting with the inverter and batteries first and then adding PV panels later. The challenge with this however is being able to have a vision of what your total system will look like before you start. 

 

Link to post
Share on other sites

Hi All

Thank you one and all for the feedback!

I phoned a couple of companies, even for a simple UPS solution the installation costs in some cases is more than the solution.

Cost really is an issue, as has been mentioned a SunySink is R22k without installation or batteries. 

@Richard Mackay thank you for this insightful feedback, I was aware the batteries were poor I didnt realise how poor. Costs have dropped a lot and continue to fall so perhaps my answer is to invest in some small UPS's, solar powered security lights and Magneto rechargeables for inside the house.

 

@Paul Greeff, thank you for this it was also something I was considering. I dont suppose there are any electricians on this forum? In my minds eye, I am thinking of a low load zone and a "caravan plug" placed strategically in the garage?

Thank you once again!

David 

Link to post
Share on other sites
3 hours ago, OceanWanderer said:

 

@Richard Mackay thank you for this insightful feedback, I was aware the batteries were poor I didnt realise how poor. Costs have dropped a lot and continue to fall so perhaps my answer is to invest in some small UPS's, solar powered security lights and Magneto rechargeables for inside the house.

 

Steer clear of inverter UPS's if you can. These devices generate 220V which often isn't required. They draw a heavy battery current even when there is no load connected.

Link to post
Share on other sites

Apologies for the delay (but I also notice this discussion isn't embraced by the forum)

The list of devices are all low voltage devices (not 220V)

This provides an opportunity to power these devices directly at the voltage they require. The advantages are enormous: Smaller (cheaper) batteries providing the same backup time as the huge inefficient UPSs & batteries. 

LEDs inside and outside change to low voltage fittings and add battery backup (12V) You only need to change some of these IMHO since you don't need all the lights on during outages

The CCTV system is probably 12V so all you need to add is a battery. Send me details of the system..

WiFi and router can be kept going for the whole day (+8hrs) with this device: https://pupups.co.za/ @R850

Laptops have batteries. If you need extra battery capacity buy another battery and keep charged (cheap at the price!)

Link to post
Share on other sites

Powering from DC I'd recommend the following:150+66

Avoid lead acid, else you will have to come up with a "BMS" for these to ensure you only draw a certain %age out of the battery, lets say 20% and have a decent charging circuit that won't get the battery into gassing territory on re-charge to enable a reasonable life out of these

I recommend a LiFePO4 pack per application with BMS and charging circuit for the the battery pack, again limited discharge and ideally also charge, if you can calculate your need per consumer item/battery pack and keep the charge to 90% max and on the bottom end above 20%, you can likely expect 10+ years out of the battery pack assuming, of course your current draw is less than 1C, which is most likely to be, I'd imagine more like .2C or so, which again is a recipe for a longer life for these

Now since you're running 12V devices, maybe best would be to gather them all together (proximity to each other to keep cabling doable?) and run one LARGER 12V LiFePO4 battery with BMS and charger that can talk to BMS and keep things within certain limits >20% <80% and for the 19/20V laptop, you can probably run a DC to DC boost converter that takes the 12V and gives you 20V, I do this for an old Dell Laptop, where the original charger let out the magic smoke a few years ago and the battery pack, by now, is toast as well.

You'd need to calculate, for the DC devices, what running time/period you'd expect and do the sums to come up with the capacity batter(y/ies) required.

As an example: 100+42+12+12+150+66 as thumbsuck figures you've provided = 382W if my mental arithmetic doesn't fail me. So, let's call it 400W per hour and this is 60% of battery capacity to ensure a long life, so if you're catering for 3 hours, that would be 1k2W which is 60% of 2kW's worth of battery capacity, or around 180Ah capacity.

Now, this is overkill, since the laptop doesn't consume the 150W app. you specified, my Apple 15" retina MacBook Pro, sits here at less than 30W mostly, unless I'm compiling something etc. it isn't consuming the power that its 95W DC power supply would indicate, it has a 256GB SSD, 8GB RAM and a 3d gen i7 mobile CPU, but also I'm using an external display and not the built in display. The external display probably consumes, maybe 40W, I'm not sure.

Basically you should probably do some power measurements over a few days or so on every DC item you would look at putting on DC backup power to get a more realistic idea of what they consume, a WiFi AP may have a 1A 12V rated PSU, but probably consumes somewhat less than this specified power, let's see WiFi RF is limited to 500mW max, let's say dual band, that's 1W RF for 2W DC in, CPU etc. maybe 5W for the AP, I'd think, but better to measure, the point though, if you use the specs of the PSUs, then you will be catering for more consumption than you actually need and if lack of funds is a criteria, then more homework is needed.

* any and all typos and speeling mistakes are mine, tough, don't have the time to proofread and fix right now 🙂

Link to post
Share on other sites
12 hours ago, Kalahari Meerkat said:

Avoid lead acid, else you will have to come up with a "BMS" for these to ensure you only draw a certain %age out of the battery, lets say 20% and have a decent charging circuit that won't get the battery into gassing territory on re-charge to enable a reasonable life out of these

Lead acid batteries are ideal for power backup systems. This is because they aren't cycled every day (which Li-Ion is much better at) and the batteries will be a fraction of the size and price of what you will need compared to an inverter backup solution. (And you won't need a BMS for a 12V SLA battery!)   

All devices that have batteries will mange them e.g. charge and cutout voltage. 

Remember this Mini UPS solution is an energy efficient solution to help you survive power outages. It is not a solution with PV panels, inverters etc. and dreams of going off grid! 

Link to post
Share on other sites
On 2021/02/23 at 9:39 PM, Richard Mackay said:

Apologies for the delay (but I also notice this discussion isn't embraced by the forum)

The list of devices are all low voltage devices (not 220V)

This provides an opportunity to power these devices directly at the voltage they require. The advantages are enormous: Smaller (cheaper) batteries providing the same backup time as the huge inefficient UPSs & batteries. 

LEDs inside and outside change to low voltage fittings and add battery backup (12V) You only need to change some of these IMHO since you don't need all the lights on during outages

The CCTV system is probably 12V so all you need to add is a battery. Send me details of the system..

WiFi and router can be kept going for the whole day (+8hrs) with this device: https://pupups.co.za/ @R850

Laptops have batteries. If you need extra battery capacity buy another battery and keep charged (cheap at the price!)

I'd go for a Ratel / UltraLan / Gizzu above the pup though

Link to post
Share on other sites
6 hours ago, Richard Mackay said:

Lead acid batteries are ideal for power backup systems. This is because they aren't cycled every day (which Li-Ion is much better at) and the batteries will be a fraction of the size and price of what you will need compared to an inverter backup solution. (And you won't need a BMS for a 12V SLA battery!)   

All devices that have batteries will mange them e.g. charge and cutout voltage. 

Remember this Mini UPS solution is an energy efficient solution to help you survive power outages. It is not a solution with PV panels, inverters etc. and dreams of going off grid! 

Problem is though when extended loadshedding hits the LAs don't have sufficient time to recharge. This was the problem with my home alarm battery which would give a continual low battery warning beep for the last 30mins or so of a loadshedding shift (particularly unpleasant during overnight shifts) so I changed my alarm to work off an UltraLan (as well as the LTE router). Loadshedding became a non-event. 

Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...