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I want to install a photovoltaic system in a shelter in my garden, because it has a very good south exposition (my house is not south and shaded by high trees) and a reasonable surface (20 m2).

I am planning to install 3 or 4 kW of panels, and also some storage, to start 5 kWh lithium batteries, maybe more afterwards.

The shelter is a little far from my home, around 50 meters. It is not a shed/small home so underneath it will be exposes to rain, wind, etc.

Two questions related.

FIRST
Shall I
A) put the inverter + batteries near my home, and use 50 m DC cable? (I know it is more expensive), or
B) should I try to protect inverter + batteries with some kind of electrical cabinet? And use an AC cable?

What about panels in parallel / series? I think inverter handle 85 to 520 volts.

In case A , doing some calculations I imagine I'd best put all solar panels in series (8 panels 38 V, VOC) to lower the current and thus voltage drop losses in the DC cable. I obtain 4 V of voltage drop and 20 W of losses.

In case B, shall I make instead a combination of series & parallel for some reasons?

Any advices, including pros and cons with safety concerns are most welcome!

Transistor
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mapStack
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2 Answers2

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If you do the paperwork and look at the wiring diagrams for the system, this should answer itself.

You need a building permit. Post the requirements document for your locality. Post the system wiring diagram and general physical arrangement for the components showing how they comply with the local requirements. Post any documents your utility has on solar ties. Check what electricity billing schedules and riders are necessary to participate in net metering.

There usually isn't much flexibility left after meeting the rules.

How many wires go from the shed to the inverter if the inverter is in the house? how many wires go between the house and the inverter if it is in the shed (15? 20? if using an all-in-one inverter/converter/charger/gridtie). If you have separate inverters and grid tie devices, then you could move the solar inverter into the shed, as well as the batteries and battery charger/inverter (assuming the shed is a permitted structure). But most people seem to be opting for the all-in-one hardware. There will be code implications to doing this. You will need additional disconnects on the house and on the shed. In many areas you aren't allowed to do this at all.

Phil Sweet
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All else being equal (which it never is), you put the batteries away from the house (because of hazard), and you minimize DC links (because of hazard).

The batteries have enormous energy storage -- like a bomb --, and the DC link can arc -- like an arc welder --, and the DC link isn't low enough voltage to be a low-voltage system, so it has the same voltage hazard as the AC system anyway.

So you start with the batteries and inverter at the shed, and you see if it is legal and you can get permits. If not, you check to see if a DC-interconnect system is legal and permittable.

david
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