Today, we received our newest order of solar panels from Amorn Solar.

In the top of frame, you can see 6x 300W panels. Each is pretty big, measuring about 2m by 1m. Together, they should really have plenty of power to run the entire house. Down below, in the small white box on the left is another unit of the same charge controller we used on the pond circulation pump. Right of it is a 60psi 19lpm DC water pump that we intend to use as the main water pump for the house. To the right of it (hard to see because it is black and in the shadow of the pump box) is the new main charge controller for the solar.

The panels are a bit funny in that we ordered “24V panels”, but the manual of the model that arrived says the open circuit voltage is 44.5V and the maximum power voltage is about 36V. So I would call this a “36V panel”. But it may actually work better than real 24V panels when charging 24V batteries since the charge controllers may be using only “step down” circuitry. (A 24V panel may not be able to supply the ~28V that a 24V battery needs to charge and still get full power.) But this is only if the charge controller can handle the voltage.

The cheaper smaller controller says it can handle an open circuit voltage of up to 50V, which is greater than the 44.5V of these panels. On the newer more expensive controller, I was intending to put two panels in series for input but still use 24V batteries. This should still be possible since the manual says it can handle up to 96V of solar panel input which is more than 2*44.5V=89V. Both are a bit slim on safety margin, but should still work okay.

So the idea now is that at least all of the indoor and outdoor lighting, the main house water pump, the outdoor water pumps to move rainwater into a storage cistern, and the ceiling fans in the house will all be running off of 24VDC and supplied by these solar cells.

On top of that, if possible I’d like to set up DC supply for laptops and multimedia computers, cell phone charging, etc. If the estimates I’ve seen are correct, then the 6x 300W panels ought to be able to supply about 10kWh of electricity per day on average throughout the year. (Obviously rainy days would be less than sunny days.) Even if there is up to a 20% loss due to battery charge/discharge, this is still 8kWh of electricity supply. In order to take full advantage of this, we would need to switch more than just lights and fans and computers over to the DC circuitry. The remaining big items are probably refrigerator, TVs, microwave, and cooking stove. My guess is the TV wouldn’t be too difficult with an inverter, but the others would probably require very large inverters and possibly bigger batteries. So maybe I’ll start by targeting just the TVs.

I may pull 2 of the panels to run the other set of circulation pumps on the land in the meantime, if they aren’t needed on the house.