Solar generator design considerations

The last few days I was browsing through some DIY sites to get the basic ideas on how to build customized solar generators. Before delving into these basics, let’s look at the bigger picture: are we going for an off-the-shelf product or are we going to develop our own version by using the basic components of a typical solar generator?

According to the reply we got from Mika this week, the plan is to make use of locally available materials in the target regions instead of supplying the final product from Europe. If so, it is apparent that the task is to come up with a design/prototype that utilizes easy-to-find components that are low-cost whilst maintaining an acceptable level of efficiency.

In my opinion, our solar generator model needs to have at least the following basic components:

1. Solar charger (solar panel with built-in battery)

Points to consider – its physical dimension, rated output voltage (12V DC, 16V DC or 24V DC?), rated output power (150W?), short circuit protection (should come with the system), cabling (for connection to the inverter) …

2. Inverter

Points to consider – input voltage range (10-15V DC, 10-24V DC?), rated power (150W? needs to be compatible with the solar charger), rated output AC voltage (230V AC), cabling (to the solar charger [DC input] and also to the power distribution terminals [AC output]), AC short circuit protection & DC reverse polarity protection (should come with the system) …

3. Enclosure (panel)

Points to consider – protection class (IP class), installation type (fixed or mobile), ventilation (for the inverter, which dissipates significant heat) …

4. Power distribution terminals

The NSN GAP (GSM Access Point) set-up shows two equipments (UPS & 48V DC rectifier) connected to the generator. Hence, socket points (distribution board?) are needed, perhaps with protection? …

5. Meters

Is it required to monitor the levels of AC voltage/current & DC voltage/current? May be already integrated with the inverter; otherwise, separate meters needed? …

In principle, the generator in the NSN GAP scheme shall feed (at the minimum) the Flexi EDGE BTS and the PC (computer). In the case of the BTS, the generator first feeds the 48V DC rectifier (which converts 230V AC to 48V DC). Then, the rectifier feeds 48V DC to the BTS and it also charges a 48V battery system, which is a backup source for the telecom equipment.

We need to know the total consumption of the NSN package in order to determine the type of devices that can be connected to the extra available power from the solar generator.

Obviously there will be more points to consider but let’s explore these for now!

List of the Power Consumption of Typical Household Appliances

The following may help to compare the power consumption of some appliances.
http://www.daftlogic.com/information-appliance-power-consumption.htm
It just for comparison, how many of them can be powered by our 150W system.

Internal meeting (27th)

This afternoon we had our internal meeting to discuss further about the project plan for our group work. Although this was the main agenda for the meeting, it turned out to be a good opportunity to make an in-depth analysis about the nature of our project.

Our discussions included product reviews of portable solar chargers from the company (PowerFilm, Inc) that was identified by Pasi. We also talked about NSN’s Village Connection solution, what could be their experience from previous releases and what are the likely scenarios under which their package can fit in to the solar power solution we plan to design. A number of questions were raised related to these points and the same will be forwarded to our mentor Mika Skarp.

We emphasized on the fact that we need “to be innovative and think of different approaches or concepts… [where such a product] could serve a wide range of needs or applications in the remote areas of the world”, as explained in our project description.

The ‘stakeholder analysis’ part of the project plan was also on the table for discussion. It was in fact a continuation of what we have already started during last Monday’s lecture. And the discussion of today yielded a list of additional stakeholders; more importantly, we tried to analyze how they are linked to each other. Ideas were also shared on how to structure our forthcoming workshop as well the final report itself.

That was it (more or less) for the day…we now go to work on our individual tasks to produce a good project plan for early next week.

PowerFilmSolar

Here you can find a link to one interesting company´s webpages: www.powerfilmsolar.com. (especially the products & applications sections).

Participatory Methods 1

In my opinion the presentation by Dr Paula Siitonen gave us better insights into the important concepts of participatory methods. The very first exercise we jointly did with the string was a good reminder to all of us about the fact that we all are part of a bigger network and, through our various interactions, we are either impacted by or impacting this network.
From this we can deduce that successful participatory planning requires an in-depth understanding of the dynamics involved in the interactions of various social groups, individuals, authorities and organizations.
The tasks given during the lecture such as identifying the stakeholders of the respective cases were quite helpful to come up with ideas that will later serve as a basis for preparing our project plans.
The last part of the session, the exhibition walk, gave each participant the chance to explain the individual case on which he/she is working on and it was also an opportunity to learn what is actually going on in the other groups and to suggest ways that may help them to improve their work.
Overall, I can say that it was a highly interactive and equally entertaining session.

How did you feel about today's lecture?

I think, it helped us to get ideas from other groups, with a different insight. Specially, the last workshop was cool, it initiated everyone to equally understand the task in progress.
And also I got some new ideas from other projects like
- The 'waste' plastics generating business and employement opportunities.
- How blocking a river, like in dams, distorts the ecosystem some fishes are unable to migrate.
etc.
This type of interactive workshops are enjoyable and effective than the traditional one way 'broadcasts'.

Review on Suntrica Ltd

I have gone through the various sections of the website. Below is a brief summary of my findings:

Suntrica Ltd is a recently established Finnish company specializing in the production of solar chargers that are designed to be used with portable battery-powered devices such as mobile phones, digital cameras & GPS devices.

The key features of its products are flexibility, efficiency, portability, adaptability & ease of use.

At present it has three main products on the market, which are shown below:

Solar Strap

Solar Badge

Solar BadgePro

Each product gathers solar energy via a flexible solar panel & stores the energy in an internal lightweight battery for instant or later usage.

The service voltage is 5V DC, which is common for most portable personal gadgets. Compatibility to devices from various vendors is achieved by an assortment of adapters.

The product can alternatively be charged from an electric wall socket.

There is no pricing information. So, it was not possible to estimate how far it can penetrate the developing world market.

Tests will be needed to confirm the functionality of the product under different atmospheric conditions. It will be quite interesting to know if the declared charging times can really deliver the corresponding talk-times.

Comparison of different energy sources

You can compare the capacity of different energy sources, Solar, Microturbine, Fuel, Wind and Internal Combustion Engine.
http://www.solarbuzz.com/DistributedGeneration.htm

Time for weekly meeting?

The Monday afternoon wasn't suitable for all, so;
When would you have time, if we could meet at least weekly in the beginning of the project?
Personally I feel that it would be good to do some "brainstorming" especially in the very early point.

Beginning of the Blog

Our project began today with the first lecture and group meeting. Our assignment is Innovative Solar Power for Remote Communities. The solar power technology in question is explained further online at: http://suntrica.com/