Essential standby equipment, energy use and solutions

[ProDave]

I have long moaned about my roughly 75kWh "non heating" electricity use each week, and finding out what it is and how to reduce it.  I have finally made a start tackling that.

 

The under stairs cupboard contains a lot of essential stuff most of which is on 24/7 so seemed an easy place to start.  This includes satellite tv receivers, the printer, and all the network gear including the router, VOIP phone base unit, NAS storage etc.  All stuff than needs to be on 24/7 but I know it consumes a lot of power.  So time to measure it.

 

I rigged up a couple of extension leads to power all this kit from one plug and made a loop of cable to allow my clamp ammeter to measure the power consumed, and came up with a total of 0.5 Amps, rising to 0.6 of the printer is printing.  That's 120 VA

 

If I assume most of it will be a poor power factor, lets take a guess that it translates to 100W as seen and metered by the electricity meter.  that's 2.4kWh per day or 16.8kWh per week or 22% of my "non heating" usage.  And at the present capped electricity rate of about 33p per kWh it is costing £289 per year to power that lot.

 

So thoughts are turning to how to power that lot by adding more renewable power?  Being an almost constant load and low power, and all together in one place, this seems a possible candidate for a little bit of off grid renewable power generation with a small amount of battery storage.

 

Initial thoughts?  A 12V system based on a large leisure battery for storage, charged from a few more solar PV panels and also a small wind turbine.  Rough costings:  Cheap "500W" wind turbine £150, leisure battery £100, solar PV panels £200 Add in sundries and that is going to be about £500 of expense.  Theoretical payback of 2 to 3 years perhaps.

 

So I expect that will be the main content of the thread, to design such a system, work out if it will actually work, and cost it properly, including an estimate of battery life and periodic replacement costs.

 

The choice of PV and a small wind turbine to charge the battery are to try and get more generation in the winter.  And it will once and for all confirm if a small cheap wind turbine is any good in a domestic setting.

 

Control will probably be an Arduino Nano.  All it has to do is monitor the battery voltage, switch out some generation or switch in a dump load if the battery voltage gets too high, and switch on a mains charger if there is insufficient renewable power and the battery voltage gets too low.

 

 

[Alan Ambrose]

Ah, I’ve been looking at this subject this week as I just installed the Bright app. I’m getting a ‘base load’ of about 180W including fridge/freezer, router hubs etc & other misc loads  e.g. fire sensors and cameras. I have not tried measuring each load separately yet - I’m guessing the fridge/freezer is the biggest part. I had the same thought as you - this should be the most cost effective slice to deal with. It represents 32% of our total electricity use - the rest is hot water, lighting, cooking and a little heating. Most of our heating is wood stove.

 

Alan

[SteamyTea]

Did this exercise over a decade ago. I have virtually no parasitic loads now. 

Rather than look to power it renewably, is there anything that can be properly switched off i.e. printer.

How about a bit of electronics that senses one half of a co dependant bit of equipment that turns on the other bit i.e TV and satellite box or sound system.

 

As nice as it is to have everything instantaneously available all the time, a few seconds wait is not a killer. 

Was only 45 years ago we had to warm up the TV.

[ProDave]

If you are going to power part of the house "off grid" this really needed thinking about when the house was built.  I didn't.  I have chosen this cupboard full of stuff as it is all together in once place, and is the once place in the house I can pull a new cable in through the hockey stick that goes down through the floor and emerges outside just above ground level.  So easy to get a new cable to bring the off grid supply into the house.  Getting a similar off grid feed to the fridge would be nigh on impossible.

[andyscotland]

I assume you mean taking the leisure battery through an inverter? The thought occurs that most if not all of that kit will internally be low-voltage DC electronics. The inverter & subsequent power supplies must contribute a reasonable level of losses on a 24/7 basis.

 

I wonder if there's a case for trying to find a way of powering some of it directly from the DC leisure battery supply...?

[ProDave]

2 minutes ago, SteamyTea said:

Did this exercise over a decade ago. I have virtually no parasitic loads now. 

Rather than look to power it renewably, is there anything that can be properly switched off i.e. printer.

How about a bit of electronics that senses one half of a co dependant bit of equipment that turns on the other bit i.e TV and satellite box or sound system.

 

As nice as it is to have everything instantaneously available all the time, a few seconds wait is not a killer. 

Was only 45 years ago we had to warm up the TV.

Sadly not.  All the network / internet stuff needs to be on 24/7.  the printer takes a few minutes to grind through a "callibrating" routine when powered on so would be a nuisance waiting for it.

 

But the big one is the satellite box.  It's an old repurposed Sky HD box.  It takes about 4 minutes to boot up upon power being turned on, but in any event it needs to be on if you want to record something.  It is old obsolete technology but there are reasons I keep it and probably will continue to use it until it stops working.  I have a spare Humax satellite PVR that i could use instead which probably consumes less power, but would be more clumsy to use.  I already have the sky box on a time switch, it comes on at 1PM and turns off at 1AM it is unlikely I will be watching or recording anything during that off time.

[dpmiller]

could the printer be on a time switch too?

[Alan Ambrose]

Anybody else have actual numbers for their base loads? It would be handy to see what the realistic ranges are.

 

Alan

[ProDave]

2 minutes ago, dpmiller said:

could the printer be on a time switch too?

I tried that, but each time it turns on it grinds through this "calibrating" routine, and I suspect that has resulted in much shorter toner cartridge life.

[SteamyTea]

Does seem that you value convenience over energy costs.

 

Look at a new printer, they are still pretty cheap. 

 

I have a tiny wireless router that connects to all the RPis. The energy usage is really too small to measure, may try to measure it again now I have a better meter.

Later today I shall have a look at last week's zero power draw (less than 1 Wh), think the last time I looked it was over 60% of the time.

 

Not having stuff on is the real secret.

[SteamyTea]

Just now, Alan Ambrose said:

Anybody else have actual numbers for their base loads?

I do. Shall post something up when I get back home.

[ProDave]

10 minutes ago, andyscotland said:

I assume you mean taking the leisure battery through an inverter? The thought occurs that most if not all of that kit will internally be low-voltage DC electronics. The inverter & subsequent power supplies must contribute a reasonable level of losses on a 24/7 basis.

 

I wonder if there's a case for trying to find a way of powering some of it directly from the DC leisure battery supply...?

Probably some of it could be.  Certainly a few things are USB powered so 12V USB supplies would work, but they are tiny, almost insignificant loads.  No hope of that with the bigger loads like the printer and satellite box.

[Kelvin]

20 minutes ago, SteamyTea said:

Does seem that you value convenience over energy costs.

 

Look at a new printer, they are still pretty cheap. 

 

I have a tiny wireless router that connects to all the RPis. The energy usage is really too small to measure, may try to measure it again now I have a better meter.

Later today I shall have a look at last week's zero power draw (less than 1 Wh), think the last time I looked it was over 60% of the time.

 

Not having stuff on is the real secret.

Like calories. Easier not to consume them than run them off. 
 

Apart from the fridge freezer and the boiler the only thing that is on permanently in our house is the printer for the same reasons as above because it consumes ink on start up. We got shot of the PVR because most things are on catch up so no need to record much so removed a box. We don’t use a landline any more so that removed another box. The computer equipment is only on when I need it including the NAS. Our internet is via Starlink connected to a separate router and two BT Wholehome Discs (was three) This does consume a lot of electricity relatively so is switched off overnight. 
 

I’ve not worked out our background load but will do. Our electricity consumption is about half the typical amount though. 

[ProDave]

The satellite box is mainly because freeview reception is poor.  We do use catchup occasionally, but I hate the fact they block you from skipping the adverts, so that is only a last resort when something failed to record, or I did not know about it in time to record it.

 

It is certainly easier for someone living alone like @SteamyTea to only turn stuff on when you need it and tolerate the start up delays.  In a normal household, the rest expect everything to just work, whenever wanted, whatever time of day or night.

[billt]

41 minutes ago, ProDave said:

But the big one is the satellite box.  It's an old repurposed Sky HD box.  It takes about 4 minutes to boot up upon power being turned on, but in any event it needs to be on if you want to record something.  It is old obsolete technology but there are reasons I keep it and probably will continue to use it until it stops working.  I have a spare Humax satellite PVR that i could use instead which probably consumes less power, but would be more clumsy to use.  I already have the sky box on a time switch, it comes on at 1PM and turns off at 1AM it is unlikely I will be watching or recording anything during that off time.

 

You could look at TVHeadend which will run on a RPi, as long as you don't want any of the encrypted channels. I run it on a RPi 4 with a TVHat for terrestrial TV, but it can be used with satellite receivers. Pretty low power consumption although it's a bit nerdy to set up.

[Radian]

I started a similar topic back in september:

 

The big benefit was to be blackout-proofing for the essentials like internet and heating. I concluded I needed 2.4kWh battery storage and 800W inverter to be useful. Unfortunatley the required outlay of around £1300 proved too much for a 'nice to have' at the moment.

 

My baseload ignoring fridge freezer is a fairly predictable 200W which is mostly the routers, NAS, Sky box and a  handful of Rpi's plus all the smart gadgets sprinkled around:

 

 

The mouseover above at 6:20 is in a gap where the fridge and freezers (little red blips and yellow humps) is a fairly predictable 200W. These power traces are superimposed on the total grid measurement in purple.

 

 

[SteamyTea]

31 minutes ago, ProDave said:

is certainly easier for someone living alone like @SteamyTea to only turn stuff on when you need it and tolerate the start up delays.  In a normal household, the rest expect everything to just work, whenever wanted, whatever time of day or night

Why you have to take the option away from them, not going to happen on its own.

[SteamyTea]

@Alan Ambrose

 

So last weeks usage.

Mean power draw of 0.1 kW, so 16.8 kWh for the week, 7 kWh day usage and the remaining 16.8 kWh night usage.

69% of the samples are Zero Power (78,931 samples, mean sample time 7.7 seconds).

 

[Alan Ambrose]

Ah, so 100W base load? Does that include fridge/freezer etc?

 

Alan

[SteamyTea]

Just now, Alan Ambrose said:

Ah, so 100W base load? Does that include fridge/freezer etc?

 

Alan

If that was a reply to me, then no.

The 0.1 kW is the mean load for everything. It is actually a little higher but I rounded the result, use about 3.3 kWh/day, so about 138 W.

It could be argued that at nearly 70% of the time I draw no power at all, my base load is 0 W.

 

[S2D2]

On 06/11/2022 at 11:01, Alan Ambrose said:

Anybody else have actual numbers for their base loads? It would be handy to see what the realistic ranges are.

 

Alan

41W, 67W including fridge freezer. It used to be 27W before some convenience additions.

 

I have no use for a printer or Freeview box, on-demand covers everything. NAS is very low demand so is just a hard drive on the raspberry pi.

 

@ProDave measuring each device would be useful, without knowing details of your setup I'd guess spinning disk drives make up a good chunk of the power draw, SSDs would reduce this. The problem with off grid is 100% availability and diminishing returns, the capital investment to absolutely guarantee this circuit doesn't go down for a few hours over a few weeks of winter would probably negate any savings. I would be interested in the performance of the very cheap wind turbine mentioned though.

 

Edit: Just noticed the mains charge backup, this may make the system viable if you assume something like 25% will come from the mains charger, counteracting the diminishing returns

 

Edited November 7, 2022 by S2D2

[Ferdinand]

On 06/11/2022 at 10:00, ProDave said:

that's 2.4kWh per day or 16.8kWh per week or 22% of my "non heating" usage.  And at the present capped electricity rate of about 33p per kWh it is costing £289 per year to power that lot.

 

Won't that be an overestimate as it is covered by solar when you have insolation?

 

At 1250 hours per year sun that would be about 15%.

 

Unless I have misunderstood your DIY solar.

F

[ProDave]

14 minutes ago, Ferdinand said:

 

Won't that be an overestimate as it is covered by solar when you have insolation?

 

At 1250 hours per year sun that would be about 15%.

 

Unless I have misunderstood your DIY solar.

F

At the moment of course when the sun shines this base load will be powered by the sun.  But I am talking here of shifting this collection of stuff onto an off grid supply, so it would no longer benefit from the rest of the solar PV. 

 

And the other side if the equation, on a day like today, not a breath of wind and grey overcast sky, the off grid system would not be doing a lot so the mains charger would be kicking in.

 

So savings will not be as much as the theoretical maximum, and harder to actually quantify.

[jack]

Is there a formal definition of "base load"?

 

If it means the absolute minimum, then we're somewhere around 300 W. 

 

I recently realised that I'd disabled the UFH pump switch controller in our home automation setup when doing some testing a couple of years ago, so it's been on continuously since then. I need to reprogram it so that it's only on when:

• the ASHP is running
• there's a significant difference between the slab temp in the kitchen (which gets more solar gain than anywhere else) and the slab temp in the TV room (which is under carpet and gets zero solar gain)
• there's a significant difference between the supply and return temps on the UFH manifold.  

That should save 20-30W a significant proportion of the time.

[Carrerahill]

On 06/11/2022 at 10:00, ProDave said:

I have long moaned about my roughly 75kWh "non heating" electricity use each week, and finding out what it is and how to reduce it.  I have finally made a start tackling that.

 

The under stairs cupboard contains a lot of essential stuff most of which is on 24/7 so seemed an easy place to start.  This includes satellite tv receivers, the printer, and all the network gear including the router, VOIP phone base unit, NAS storage etc.  All stuff than needs to be on 24/7 but I know it consumes a lot of power.  So time to measure it.

 

I rigged up a couple of extension leads to power all this kit from one plug and made a loop of cable to allow my clamp ammeter to measure the power consumed, and came up with a total of 0.5 Amps, rising to 0.6 of the printer is printing.  That's 120 VA

 

If I assume most of it will be a poor power factor, lets take a guess that it translates to 100W as seen and metered by the electricity meter.  that's 2.4kWh per day or 16.8kWh per week or 22% of my "non heating" usage.  And at the present capped electricity rate of about 33p per kWh it is costing £289 per year to power that lot.

 

So thoughts are turning to how to power that lot by adding more renewable power?  Being an almost constant load and low power, and all together in one place, this seems a possible candidate for a little bit of off grid renewable power generation with a small amount of battery storage.

 

Initial thoughts?  A 12V system based on a large leisure battery for storage, charged from a few more solar PV panels and also a small wind turbine.  Rough costings:  Cheap "500W" wind turbine £150, leisure battery £100, solar PV panels £200 Add in sundries and that is going to be about £500 of expense.  Theoretical payback of 2 to 3 years perhaps.

 

So I expect that will be the main content of the thread, to design such a system, work out if it will actually work, and cost it properly, including an estimate of battery life and periodic replacement costs.

 

The choice of PV and a small wind turbine to charge the battery are to try and get more generation in the winter.  And it will once and for all confirm if a small cheap wind turbine is any good in a domestic setting.

 

Control will probably be an Arduino Nano.  All it has to do is monitor the battery voltage, switch out some generation or switch in a dump load if the battery voltage gets too high, and switch on a mains charger if there is insufficient renewable power and the battery voltage gets too low.

 

 

I am sort of doing a similar project, I am taking loads off-grid. When I wired the house I split things up a lot more than normal, so for example, my comm's cupboard is on one radial, other rooms are on radials, fridge is on an essential supply etc. the idea being I can start pulling certain loads or areas off grid by connecting them up via battery/PV inveters.

 

By next summer I hope to be running all the background loads totally off-grid (with grid backup link) and my external and internal lgt. circuits off-grid too. The house will still have its grid tied PV system, which will help whittle down the grid demand, but it will really only then be running variable loads during the day and we will import the remainder. By 2025 I hope to be off-grid albeit with grid backup via the inverters, with a plan to have the electricity disconnected by 2026.

 

I am going 24V system for the small inverters, I will go 48V when I start going to the bigger inverters. I am using Victron Smartsolar chargers and not made a call on the inverters yet.