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reyoztoday at 11:46 AM1 replyview on HN

This is what I am doing. 42 kWh battery, 6 kW solar and fully electrified house, 2x EVs. I am able to charge cars at work and so in the depths of winter I am able to run the house by charging during the 3 hour window. There have been just a couple of cold (~2-4 degC) days when the battery was depleted 1-2 hours before the window starts.

As the weather warms and we get more solar exposure we will easily be in excess. We get a very small export rate with a bonus for no energy consumption during peak evening hours which can offset the fixed daily charge.

There are a lot of gotchas that you need to be aware of. 42 kWh is nominal capacity not the actual usable capacity. House load, max grid import and export capacity, max inverter capacity, AC or DC coupled panels, battery charging profile, battery temp are all factors in how much you can charge in the window. For example I have max 15 kW grid draw, with a 10 kW inverter that can charge the battery. I can put in max ~30 kWh into the battery, so I also run other loads in the house to use the other 5 kW capacity. If I go over 5 kW house load the battery charge is clipped to maintain grid import limit.


Replies

throwaway2037today at 12:20 PM

    > I am able to charge cars at work
Nice perk! Does you know who pays for the electricty? Is this "virtue signalling" by the company or landlord... or a subsidy from the local/state/national gov't? To be clear, I am not making any value judgement about providing free charging for EVs. It seems like good gov't policy to promote the adoption of EVs.
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