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Newbi Requires Advice on a PV ONLY Build.


Graphixlab
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Hi Guys.

 

I need help with a setup.....

 

Location:                          DURBAN KZN.

Available Flat Roof space:   Area 66m2      (6mx 11m)

 

We would like to generate as much electricity as possible during the daytime to slow the electricity meter right down

or hopefully even make it spin backwards.

 

We are not looking at getting off the grid 100% and do not want batteries etc...

Only a good daytime saving setup to run the pool air cons etc.

 

Can I have your thoughts on this and recommendations on what's the best equipment to purchase ?

 

Kind Regards,

 

Kevin

  

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With 66 square meters... you have your standard 1000Wp sunlight per square meter, so that's 66kwp incoming insolation, but PV panels are... what... maybe 17% efficient? Let's say 15. Then that's just short of 10Kwp that you have space for. Assuming on average 5 hours of good sunlight per day, you can make 50kwh a day on that roof. Based on a lot of thumbsuck and assumptions of course...

 

10kwp PV panels alone will set you back R100k :-)

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Hello Kevin,

It sounds like you are trying to do what I wanted to do.

Reduce my daily load to solar as much as possible and have enough battery backup for load shedding, maybe with space to expand that, if you wanted to

Later.

Wetkits questions are really valid.

1.) understand how much you use a day kWh.

2.) reduce your Eskom load - Move to solar geyser, cheap option, check fridges are A+ or better A++, move stove and or oven to gas, or gas/electric split. Also look at how much power your pool

Pump and sitcoms use ? I have a 12btu non inverter aircon that runs on around 1kwh, I also have a older 18000btu aircon, that burns 3kwh. You need to understand what your peak kWh draw is, and that's what costs - bigger inverter bigger batteries etc. When going solar, so reduce your peak loads first.

By doing the first bits above we moved from an average of 85kwh a day to 30kwh.

The we tried to halve the 30kwh further, and the. Added a 5000va 4000watt inverter, split the db board to essential or long running items like fridges, and added 9x250watt panels, giving a peak charge of at best 2.25kwh & 245amp h C20 rating batteries.

This reduced the Eskom requirement down to around 13kwh a day - which is used mostly at night/sunset/sunrise.

Looking forward to adding the last 3 panels and second bank of batteries for longer run times during load shedding.

Currently we use continuously from 400watts to about 1000watts per hour.

Aircons and pool pump we left on Eskom for now.

At 14 kWh per day it we now Spend around R500-700 month with Eskom. For now I can live with that, but once the price climbs by 17% it will justify the upgrades.

Enjoy the journey to solar :)

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