What options do we have for powering electric circuits without access to electric grid? For instance, to power a 10 watt LED lighting at night? The motivation to the project is to add some lighting in places where it is expensive to connect to mains.
In warm countries like Spain, southern USA, Italy etc this is a no-brainer: you just need a cheap solar panel, one cheap lead-acid battery and controller. Costs like couple of hundreds of euros/dollars at maximum, and is economically feasible if compared to mains connection (which might cost thousands of euros/dollars with excavation work etc).
But in cold countries (like here in Finland) there are plenty of problems in winter:
- The solar panel gets covered with snow
- And even if you place it so that it does not, the power output is negligble
- So, a feasible solution would be to use large amount of lead acid battery capacity to get over the winter (basically December, January and February).
- But there is a but: lead acid batteries lose their capacity in cold and in addition, you can not use even this reduced capacity because the battery will freeze and break down if it is too cold. For instance, a fully charged lead-acid battery will freeze at -70 °C (which is not a problem), but a battery with 50 % SOC will freeze in about -26 °C, which can happen here in Finland (this cold it is not very common in souther Finland but it is possible, for couple of days).
Is there any feasible alternative ways to solve the problem? The best option I've found so far is methanol fuel cell, the lowest power systems cost 3000-4000 euros/dollars so it is still cheaper than a mains connection.