SAN rooftop

Benefits of producing power at the point of consumption

By Conrad Roedern

Residences,office buildings, schools, workshops, factories and supermarkets share one common denominator; they require electricity to fulfil their function. Except for residences, the majority of this power usage takes daytime and this coincides perfectly with Namibia’s 300-plus sunny days.

The way to go is PV Solar Feed-In System which helps to make money by saving on cost of electricity. Since now home generation has crossed “grid parity”, i.e. generation on site seems cheaper than buying electricity from the grid, such an investment comes with typical pay-back period between five-eight years.

Savings are not attributed to avoided power purchases but also by exporting excess under the new net-metering law. Depending on the daily load curve, further savings could be made from lower maximum-demand-charges, time -of-use charges or by lowering the amperage of the incomer’s main circuit breaker which governs the bulk part of basic charges. Obviously demand side management i.e. shifting demand may greatly improve these savings. Liasing with expert companies which can provide data logging of consumption curves and other demand-side advice therefore is a prerequisite when it comes to tailor made feed-in solutions.

The new law allows renewable energy systems up to 500kVA to operate on the client side of the electricity meter where the client’s loads are served first; if larger it now will have to operate as embedded electricity generation i.e. the operator has to negotiate an off-taker price for excess with the utility. Excess is exported at a remuneration (for City of Windhoek currently at N$1.13 per kWh) which is linked to the avoided cost of the grid supplier. Thus, any feed-in system will have to make use of electronic meter which can register import and export separately.

Netmetering tarriff
Netmetering tarriff as announced by City of Windhoek for 2016/2017.Two-way meters are to be installed with all net-metering installations in Namibia

From a technical point of view such a system increases overall energy supply efficiency by avoiding transmission losses of some 25% due to our extreme line distances for importing and distributing of power.

A rooftop system makes use of otherwise unused roof space, thus adding value to a property and avoiding any conflict between energy and crop harvesting which field-mounted systems start to generate in other parts of the world. Such a PV roof can also come as a car shade for a residence or a parking lot.

In future and especially on new buildings we will see more and more genuine solar roofs where the roof surface is made of PV modules thus saving on cladding material and mounting structures. PV feed-in systems-provided a high-quality installation by an experienced supplier is performed in terms of components, planning, design and workmanship-have very low requirements when it comes to maintenance and repairs since their design life is usually for 25 year plus. The residual maintenance offers local job opportunities when it comes to professional PV module cleaning, system monitoring and eventual repairs. Buildings with integrated PV generation always clearly show investors’ and owners’ responsibility and commitment towards the environment and thus towards sustainable living for future generations. At the same time, it supports Namibia in reaching its climate goals.

From the perspective of national economics, a multitude of advantages transpire. Compared with the centralised power stations PV fee-in systems have a much higher local content with regard to design, construction and fuel supply. They are thus helping Namibia to alleviate our shortage of electricity and to improve our balance of trade while saving money from our state coffers by employing private investment money.

Expertise for systems, as described above, is well covered by the engineering capacity of experienced Namibian companies. It is beneficial to attribute this kind of installations to local firms thus ensuring constant improvement in local training creating more and more quality job opportunities for Namibians. “local is lekker!”

64kWp PV installed by NamPower during phase 1 and 212kWp installed at the Ministry of Environment and Tourism head office.



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