How can I get streak free windows?

Oh, I forgot to say I never use detergent on my cloths. I clean them with water and a scrubbing brush only.
If they’re washed in detergent I get streaks.

Something that has not been mentioned so far is that you should not use softener when washing the cloths. It contains lanolin - may as well dip the cloths in cooking oil, smears are guaranteed.

Like you OP I have lots of glass on the south-facing side of the house.
I use a car washing mitt dripping with plenty of cold tap water, an OXO blade (other brands are available) and, for any tiny amounts of remaining water, a dry microfibre cloth with a flat weave. (I know microfibre’s bad.) I don’t polish and I do like gleaming windows.
I’ve tried products, a drop of washing up liquid in warm water, diluted vinegar, different blades, chamois, linen, newspaper but water always works for me.
Sometimes DH says he’ll clean a window, uses a product but is always disappointed with his results no matter how much he tries.

A very easy remedy. White spirit vinegar and water and buff with newspaper or a lint free cloth. Works for most windows.

I have this Kercher, its absolutely brilliant. I live in a South facing house, the kitchen and front room windows are streak freeeeeeee.

After living with my mum and her must be smear/streak free obsession I go along with my father in law’s take on cleaning windows. “ If you’ve got smears/streaks you know the windows have been cleaned” ?

Oh, I'm so glad it isn't just me who ends up with streaky windows! Not every time, so that makes me wonder what I'm doing wrong. Perhaps the water isn't hot enough or there is too much sun...

NotTooOld, I do agree with you that life is too short to obsess about windows, but when it gets to the stage that actually seeing out becomes a problem and there are visitors expected something really has to be done.

The day after the Brexit referendum I was so upset by the result that I had to go and clean the windows, but I have done it since, honest.

You need to wring it out to be very dry.

I have similar windows and just use a chamois leather and warm water. Not noticed any streaks.

I've tried everything, the Karcher, vinegar, Mr Muscle, Simoniz, Lidl's own, chamois, different cloths etc

All looks great until the sun shines at a certain angle.

Distilled water might work (this is what some window cleaners use).

Elbow grease is the only thing that works and mine is just not as good as it was.

Never clean windows when the sun is on them. That for sure will leave them streaky.

I find I still get streaks with the Karcher. Have you tried a blade, the sort window cleaners use and that you would use on a shower screen? I swear by mine. See Lakeland. I've also changed to HG glass cleaner which seems better than Mr Muscle which I used before.

I'd love to know this, too. Windows look perfect when they've just been cleaned then you catch sight of them with the sun at a particular angle and they are all streaky.

Window cleaners use those scrapers, as CoolCoco says, and it seems to work for them. And they only go over it once, too.

One tip I saw on a YouTube clip was to get really good quality cloths, specifically for glass.

Or better still, chamois leathers.

Also water should suffice, but really hot water (which is why steam cleaners are supposed to be so good.) and wring out the cloth or leather as tight as you can especially for the final wipe down.

I still get streaks with my Karcher sometimes. I have a blue glass cleaning cloth and buff the windows with that after cleaning, while the window is still slightly damp.

Don't clean windows in sunshine, they dry too fast.

Scrunched-up newspaper to buff it up with while it's still damp!

I have a Karcher window vacuum it is the only way I can do streak-free windows and mirrors.

Give up and ignore the streaks. Life's too short to obsess about windows!

Try using an e-cloth.

Buy a Karcher window vacuum, and keep its squeegee spotlessly clean.