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image credit: Rafael Herzberg
Rafael Herzberg's picture
Consultant energy affairs, Self employed

Rafael Herzberg - is an independent energy consultant, self-employed (since 2018) based in São Paulo, Brazil * Focus on C level, VPs and upper managers associated to energy related info,...

  • Member since 2003
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  • Sep 8, 2021


If we take a look at each source individually, we will come to well-known conclusions.That's for sure! But, let me see the whole picture!


In real life, what really counts is how each source is dispatched as a "whole" to meet the demand.

In round numbers:

* 1 kW of national demand is associated with a monthly consumption of 600 kWh/month.
* Each source is able to produce for a 1 kW of installed capacity: (1st) solar photo-voltaic (PV)  110 kWh/month (2nd) wind 360 kWh/month and (3rd) hydro 440 kWh/month.
* All these sources mentioned demand investments of USD 1 000l/kW of capacity each.


* The competitiveness of investments related to their energy production is: (from the cheapest to the most expensive): Hydro, Wind and Solar PV.
* The amount of energy needed to complete the 600 kWh/month is: 1st) solar PV 490 kWh/month, 2nd) wind 240 kWh/month and 3rd) hydro 160 kWh/month.
* As the "backup" in Brazil is thermal power, the cost of generation is (from the cheapest to the most expensive: 1st) hydro, 2nd) wind and 3rd) solar .PV

* Emissions must be referred to the energy produced by each source separately and considered those of the backup plants. The cleanest ones, in order: 1st) hydro, 2nd) wind and 3rd) solar PV.


A systematic look points to the interest and convenience of seeking the best final  result in terms of costs and emissions, considering the backup requirements for each source.

Dr. Amal Khashab's picture
Dr. Amal Khashab on Sep 8, 2021

Hi Rafael

Your combination is not the best. It needs 5KW PV full loading + 1KW Wind partial loading + 1KW  Hydro  partial loading.The total investment cost is 5000+1000+1000= 7000$.

While another combination may be : 0 KW PV + 1 KW Wind partial loading +1 KW Hydro full loading. The total investment cost is 000+1000+1000= 2000 $.

Pollutant emission is minimum for both cases.

What do you think about that?

Rafael Herzberg's picture
Rafael Herzberg on Sep 8, 2021

Hi Amal,

Actually when you build your power portfolio you need to make sure that you have the required amount of energy 24x7. So having PV for "full loading" in your example, it would only be feasible if a proper storage package is there because as we all know at night there is no sun or even in selected cloudy days. And accordingly the associated investment would be way higher than USD 1 000/kW of PV..

So this is a very challenging puzzle. It is not, and by far, as we read to basically retrofit to a specific energy source. It is about finding a feasible, reliable and robust package for a fair price in USD/MWh.

Dr. Amal Khashab's picture
Dr. Amal Khashab on Sep 8, 2021

Yes, but you assumed that :

" Each source is able to produce for a 1 kW of installed capacity: (1st) solar photovoltaic (PV)  110 kWh/month (2nd) wind 360 kWh/month and (3rd) hydro 440 kWh/month" . This is equal to the direct assumption of 110 hours of sunlight/month with an average of 3hours and 45 minutes per day. Same as Wind 12 hours/day. This confirms their intermittency.


Rafael Herzberg's picture
Rafael Herzberg on Sep 9, 2021

Hi Amal,

When I said that 1 kW of PV Solar capacity produces 110 kWh/month it means that this was measured. In the beginning and at the end of the day the PV solar produces less kWh than at the middle of the day.

What was made is: setting up a kWh meter and record the kWh production during a month. So the kWh measured is what was delivered by the PV Solar for a nominal designated capacity.
In most areas in Brazil this is about 110 kWh/month for a 1 kW PV Solar panel. 

110 kWh/month is roughly 3,7 kWh/day. If we have as an average 12 hours of light per day it means that the 1 kW PV Solar offers an average of 0,3 kWh/h during the day. If we calculate using the 720 hours/month, the end result is half of that!

Rafael Herzberg's picture
Thank Rafael for the Post!
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