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Microinverters vs 48vdc system

peter_t

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Nov 1, 2021
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I am planning to install solar with battery storage at my home in NW Wisconsin with trees partially obscuring my panels. As I understand it, micro-inverters on each panel might be appropriate to maximize output, given the trees. But a 48vdc system would be more reliable than twenty micro-inverters and harvest more energy than a single-inverter system. Right? My home is small with a heated floor and I wouldn’t mind converting a fair amount of it to dc. I see that there is a 48vdc heat pump on the market that could heat the floor and pre-heat hot water, for instance. I have an electric car and don’t plan to disconnect from the grid given my limited surface area available for solar panels. ( I would probably let the car sit and wait during power outages, if necessary.) In the winter, I expect that the grid would be charging the batteries almost continuously, given the 48vdc panels and batteries approach. Thoughts on this would be appreciated.
 
I am planning to install solar with battery storage at my home in NW Wisconsin with trees partially obscuring my panels. As I understand it, micro-inverters on each panel might be appropriate to maximize output, given the trees. But a 48vdc system would be more reliable than twenty micro-inverters and harvest more energy than a single-inverter system. Right?

Not necessarily. Micro-inverters have been reliable, and while you have more failure points, you have 19 others when one fails.

A 48V system would have to be sized sufficiently to be able to receive and store the power from your array. A 6kW array (assuming 20X 300W panels) may need upwards of 30kW of batteries to capture/store the energy, and that will be expensive.

My home is small with a heated floor and I wouldn’t mind converting a fair amount of it to dc. I see that there is a 48vdc heat pump on the market that could heat the floor and pre-heat hot water, for instance. I have an electric car and don’t plan to disconnect from the grid given my limited surface area available for solar panels. ( I would probably let the car sit and wait during power outages, if necessary.) In the winter, I expect that the grid would be charging the batteries almost continuously, given the 48vdc panels and batteries approach. Thoughts on this would be appreciated.

Conversion to DC is usually a losing proposition vs. starting with DC. In most cases, you will never recover the cost associated with the replacement of AC appliances and rewiring to gain that ~10% efficiency improvement. Furthermore, since you state that you're going to be grid dependent for the winter, you will lose any efficiency gains with DC from the conversion of AC to DC.

The electrical energy needed to run ANY heat pump will likely beyond anything practical for your system. Heat pumps consume a large amount of energy - less than direct electric heat, but still a lot for a system to deal with. Again, since it's going to be worse in the winter, you're actually shooting yourself in the foot by going 48V heat pump... it's going to be mostly grid powered in the winter.

You really need to start with an energy audit if you haven't already done so. A good place to start is your electric bill... What do you use on a monthly basis in kWh, and what will it take to replace some % of that?
 
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