diy solar

diy solar

Why the laser focus on Idle Power?

Coming at it from a slightly different angle ... everything in your house is always on ...

Wall-warts and various other SMPS power supplies, electronic devices that never really sleep, usb charging stations to keep all your phones & usb things topped off ... fridges, freezers, coffee pots and other appliances that don't really turn off anymore and have their own SMPS power board inside them. The list is endless ...

Then, there's people ... these aren't appliances, or SMPS, or anything that consumes idle power, these are folks (wife, two daughters) who go around flipping things on and never turning them off, and who always manage to find a way to power on 10 things at once, in combinations you never dreamed possible. For a short while, I tried tracing phantom excessive loads, and it always led back to a hair curler, a heating blanket, or any other thing that you can't really argue with, because they always win the argument.

If I look at the load being reported by the inverter, there are always amps being consumed, any time of the day or night ...

Given that, and given that few of us will really monitor all of these things, with on/off switches in front of them to ensure they are really off, I'd just focus on getting your solar gear sized right, over-panel enough to cover the baseline of what it takes for *your house at idle*, and leave the inverter on all the time.

If panels aren't covering it, fire up the genny or attach the grid for recharge ...

Now, there is that one or two times a year when all the women-folk leave the house for a week-long vacation to visit the out-laws ... for that brief, glorious amount of time, everything runs the way it is supposed to, and was designed for ... efficiently ... the house is even quiet!

YMMV, but I wouldn't add up the watts, I'd add up the other family members in the house, and design from there ...
 
ksmithaz1 said:
You might re-think the wording here. People keep intermingling KWH and kW and W it gets weird. 12 panels * 400W = 4800W * 1 hour of sunshine is ~5KWH needed to recharge that battery. Or more accurately, TWO (2) additional 400W panels for 6 hours (a solar day). Perfect days and perfect sunshine and perfect panels and all that, but You only need to buy 2 panels not 12.

I know some folks were mentioning in various threads of aio's approaching100W of overhead, but I don't think any of the stuff you get today is gonna be anywhere close, and if I recall the units in question dropped dramatically with a firmware upgrade. TWO inverters with a 100W overhead each need 2400WH * 2 = 4800WH. Realistically I think my two AIO's pull maybe 50-70W combined, and they are capable of 24000W of output. Probably a good idea to know about what it is, but reality is you have to simply plan for whatever the overhead is because frankly you are going to have overhead and your system output needs to be whatever order of magnitude higher than the overhead to meet your demand/needs.

The AIO is oviously going to use more power internally while it's inverting, and keeping relays on and such than when it is in 'standby'. The idea of course is to be "on" not dead in the water.
Click to expand...
Absolutely correct, my bad…
 
ksmithaz1 said:
You might re-think the wording here. People keep intermingling KWH and kW and W it gets weird. 12 panels * 400W = 4800W * 1 hour of sunshine is ~5KWH needed to recharge that battery. Or more accurately, TWO (2) additional 400W panels for 6 hours (a solar day). Perfect days and perfect sunshine and perfect panels and all that, but You only need to buy 2 panels not 12.
Click to expand...

Gives me a chance to reference an excellent thread from a couple years ago :

diysolarforum.com

Impress your friends by using correct units and abbreviations

The following are common units and their abbreviations. Note that unit abbreviations are case-sensitive. While some units can be understood when written incorrectly, some have a completely different meaning if the wrong case is used. Avoid any possible confusion or ambiguity and use the correct...
diysolarforum.com diysolarforum.com
 
The Nut

If you have a small system with light loads, Idle power consumption is a concern. The amount it needs to stay on 24/7 in significant in percentage.

If you have a large system that is on all of the time, it is not a huge concern. You are using power to run the system all the time anyway and most of the units will consume between 30 and 70.

FYI... my Sigineer 3048 uses about 50watts 24/7.

Seems to me there is a wide gap between users types. I am off grid 24/7, so how I choose to do it will be different than the person with a cabin only occupied a few months a year. I see a lot of smaller systems being used to compare and dictate what all systems should be... silly.

Another reason I went with 48v and one big battery was not having issues with 12v losses, 12v wiring, and less waste converting to 120 which is my major consumption source.
 
Checkthisout said:
Also, some of us just hate waste. Imagine opening up a closet, turning on a 100 watt light bulb and then shutting the closet and never opening it again.

That little light, costing you 25 cents a day to run on grid or absconding with 2.5 305ah cells worth of energy per day behind a closed door, going to waste..never being used...akin to a water pipe just leaking water into the ground or perhaps a faucet drip....drip....drip....drip...all day, all night...you can't sleep....going insane.

Yeah...that idle consumption.
Click to expand...

You must not be from California.

100W x 24 hours = 2.4 kWh

2.4 kWh x $0.50/kWh = $1.20, not two bits.

If you're off-grid running a generator, $1/kWh so $2.40/day, $72/month, $876/year.

How much did you save on the one-time purchase of the inverter?

DIYrich said:
Some inverters claim a sleep type mode when there is no draw. I'm thinking the clock on the microwave, or whatever, is always on. If you have 2 inverters in parallel, the ability to put the slave in deep sleep is nice.
Click to expand...

Luk88 said:
Let's give a real world example... It is my friend's cabin. He just needs enough electricity to run a mini fridge-freezer(average 35W), charge a mobile phone and run a couple of led lights. His power requirements are fully met by a single 400W panel and a 100ah 12V battery. But the compressor startup of the fridge requires a 1kW inverter. So now he has 28W of constant load on top. Essentially another fridge. Running 24/7. Unless he goes and shuts the power down.

This means that if he fridge is off this will drain the battery on its own in 3 days. He keeps a gas generator just in case there is bad weather 3 days straight.
Click to expand...

Does the inverter have a remote on-off connection? If so, bypass thermostat in fridge so it is always on. Use thermostat to control inverters.
(If no remote, then thermostat close contactor for battery power to inverter.)

50ShadesOfDirt said:
Then, there's people ... these aren't appliances, or SMPS, or anything that consumes idle power, these are folks (wife, two daughters) who go around flipping things on and never turning them off, and who always manage to find a way to power on 10 things at once, in combinations you never dreamed possible. For a short while, I tried tracing phantom excessive loads, and it always led back to a hair curler, a heating blanket, or any other thing that you can't really argue with, because they always win the argument.

If I look at the load being reported by the inverter, there are always amps being consumed, any time of the day or night ...
Click to expand...

I represent a similar problem. I turn on air compressor, do my work, forget about it. It cycles back on in the middle of the night.
I put a spring wound timer between a plug and outlet, so that cuts power after a while.

You can put in spring wound timers, or occupancy sensors.

Previous employer installed nagware on my PC telling me to get up and stretch. I disabled it.
Current employer has occupancy sensor lights. Every few minutes I do a stretch to turn them back on.
 
I've also heard it called "Phantom load" - what is used when everything is supposedly turned off (but really on "standby")
To make sure stuff is really off you can either unplug it or turn off its power bar.
 
Idle power used to be a huge issue before PV solar panels became cheap.

So was power draw of lights and appliances. People would have separate DC distributions just for lighting and things that could operate off of lower voltage DC just because PV was so expensive.

Extra and phantom energy use is still a concern but not nearly as bad as it was. I you have the space, just add more panels

boB
 
We all have different needs. I want features and if that means I have to pay for it that is fine. In the long run if I have to buy a couple more solar panels to cover the idle consumption that is the price I have to pay. One of the features that is important to me is the program settings that allow me to squeeze as much benefit as possible from my NEM agreement.
 
The PV array in my small system is shade challenged during the winter so I want maximum efficiency. My old 3kw inverter drew 36 watts with no load. The 4 watts my new 3.5 kw inverter draws at idle was a check in the plus column for that model.
 
I picked an AIMS inverter from a chap that tried running it in his RV. Its idle is about 92w, power save mode is not very useful. Thats about 1.5kwh on a 16hr over night, longer if there isn't much sun. Thats a bit of juice to just throw to the wind. I don't idle it over night, just power on when the sun is shinning to run the well and other things.
 
I put my old cheapie spare 4 kW AIO back into action as a charger for occasional use to charge the home battery from the car's battery via the vehicle to load adapter. But when not used I turn the AIO off as it has a 45 W idle draw.

I could use the idle mode which is supped to reduce that to ~15 W but even that draw is wasteful. Over a year that's still equivalent to 800km (500 miles) of range in my car. Best it only be on when needed.
 
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