I would only buy original batteries - it seems false economy to use knock offs.
Batteries seem to be about £10 per 1ah for genuine Makita, so a 5ah battery is about £50.
I would be very cautious being bound to any single brand because of owning a couple of batteries and a charger if further tools/batteries are expensive or range is limited, it can make sense financially to switch brands.
Well yes and no. Given that I only really need a couple of selective tools in cordless form that I use a lot such as angle grinder, rotary saw, drill and impact driver (of which I have all) it would seem silly to switch brands whilst they are all working perfectly well. When they reach the end of their shelf life I shall look around. Meanwhile I will avoid generic batteries.
The catch with that is that just one battery or tool will pack in - at that point it will be uneconomic to change systems.
Rinse and repeat.
Anyone using solar-powered equipment yet… 
Is there any?
Solar as a means of charging the battery would probably work - but then is that any different to the cordless equipment in the market today.
Obviously it will be a question of playing the averages Paul. Anyway it is nothing I have to worry about at present and in any event I can always continue with Bosch Professional if I am still happy with them. They may extend their range as well.
I just thought it would give another slant to the thread… I’ve no idea what /if stuff is available… but, surely, it can’t be too far away ?
Yes, I’m happy with the Makita stuff that I have - I ws pleased to see that, for the 36V stuff, they just used two 18V batteries and kept the format the same.
In the UK I bought some hedge trimmers that have a 40V battery - they work OK but the battery format is not very convenient (they are huge)
I have a calculator that works by solar power but not sure that counts (pun intended) 
How about one of these:
A solar powered tool with be unlikely to work by direct solar power. The pv panel with charge an onboard battery which will run the tool. So you are back to square one with the high cost of replacing the battery when it goes soft. The only rechargeable tools I have are a couple of lightweight drill drivers, both Bosch. Everything else is mains powered and much more powerful and will last for many more years.
I have one in the toolbox, I don’t think that it is solar powered - beer powered maybe 
The reality of solar is that in manageable sizes it’s pretty inefficient. I have an additional battery that I use to recharge my smartphone when I’m off grid. It can be charged using either mains or its built in solar panel. When it’s low it takes about two whole days of bright sunshine to recharge. I also have a larger solar panel which I use, it will run a GPS when the sun is shining but anything with a bigger current drain stands no chance. Cordless power tools need far more instant power than a small solar panel can produce.
Fair enough David… but I reckon technology will advance…
The problem has always been being able to store electricity. Battery technology has advanced in leaps and bounds but unfortunately we still need a few more breakthroughs. My farming neighbours have a wonderful collection of electrical tools, the one I see them using most is a strimmer, but the battery pack is worn like a rucksack and although it provides the power and endurance they need its heavy and prohibitively expensive. It’s a great bit of kit and hopefully in the near future similar systems will become cheaper to buy and will be able to be run from cheaper, more compact batteries.
Understood!
I am sure that there will be further developments in battery technologies, or in other compact power sources. Although if the power density increases significantly compared with modern Li-ion batteries safety will become a big issue as they stop being batteries and start being bombs-in-waiting.
Advances in DC motors have also been a big part of the explosion in cordless power tools (and EVs in fact) - not sure if there are further improvements to be made with that technology.