Ben's Blog

With our recent solar upgrade, we are able to produce much more than our charge controller can take. In fact, on days of perfect sun (full exposure, perfect angle) we need to turn off half of the array or the charge controller, which can only take up to 80A shuts off. This sounds silly, but on cloudy days, having all these panels is invaluable. So right now we’re a bit in a manual mode of turning panels on and off based on the weather.

3 years ago we had a brutal heat wave which sent us away from our house. I vowed then to have some sort of A/C capabilities before the next one. One of the nicest thing we’ve done to ourselves was getting a “regular” fridge. While at the time, it pushed our solar install to the limits, today it’s really not a big deal to keep going, even though it’s by far our biggest consumer of electrons. So we bought an 8000BTU A/C unit, I was expecting it to be maybe “a couple of fridges” worth of power consumption, but let me tell you… This thing is 7 fridges put together! Ouch!

We’ve been testing it now to make sure we won’t have any bad surprises when the heat comes.

We’ll never have the battery bank to store and supply 70A through the night. Also true, when the Sun shines, the solar panels can most definitely keep 70A coming and more. We’ve gotten good with stove heat, at managing not heat itself, but how to buffer it in the house, to buy us time through a cold night. It looks like we’ll have to do exactly that, but with cold. Run the A/C all day while the Sun gives us more energy than we can do anything with, to buffer the house as much as possible against the heat. Nights usually provide respite from heat in the Summer, in the Winter this is also true but it’s the opposite of a respite when you are fighting the cold :).

So our panels are more than enough, our storage is essentially null for the purpose of A/C, and our charge controller is too close to its limit of 80A to funnel all the panel energy to the A/C while doing the few other things we need electricity for.

I think this tells us we need to upgrade the charge controller. This way we can have a more pleasant Summer, and more specifically mitigation of heat waves.

All for free, money wise and carbon wise. Amidst these mundane concerns of solar system design to tackle such a juggernaut device as an A/C, it is easy to forget how beautiful and elegant it is that the hotter the Sun is, the more we can turn it into Cold. How often are problems their own solutions?