Heat mats for greenhouse

[CloneAViralMess]

I have an unheated, powerless greenhouse and I've heard that heat mats are the way forward when sowing seed early in the season in an greenhouse (I do have heated an unheated propagators which I've used on windowsills in the past but I have a small-windowed dark cottage and so seedlings end up leggy and weak).

Anyone know of any battery powered or solar powered mats out there? Or perhaps alternatives that would work?

Difficult with solar power, I’d have thought, too much output required. Similarly, a battery would drain too quickly.

You could experiment with a hot water bottle overnight, especially in an insulated box so all the warmth goes up into the-seed tray. Or a tea light, using a thick metal tray above to disperse the heat evenly.

How much would it cost to supply electricity to the greenhouse?

Thank you for your reply. I like your idea of the hot water bottle.
I guess I'm quite naive as to how much power these mats need. I assumed the heat level would be really low and thought that if you can buy outdoor battery/solar powered Christmas lights then a mat would be a similar output. Ah well. Maybe it would be worth investing in some greenhouse electricity.

Mats need less power than I thought, about 17W, propagators are rather heavier on power than that. But mats may struggle to maintain temperature in an unheated greenhouse. I looked up some battery lights on Amazon which gave a wattage of 3.5.

Biggest cost on greenhouse electricity is labour, as it has to be either installed or inspected by a qualified electrician.