The issue of buy-back rates is of fundamental importance to grid-connected PV installations for the short-term diffusion of PV technology. A study to catalogue the different buy-back models of selected IEA member countries is presently being finalized.

The survey identifies seventeen different models, varying in the level of remuneration offered, their metering arrangements, and whether the buy-back rate is payable for all the electricity produced or only the surplus not used directly by the system owner.

The study's key targets are to assess the advantages and disadvantages of each model, and to gauge the success of the various schemes to feed experience back into future buy-back mechanisms.

Very low buy-back rates, e.g. less than 70% of the retail price, are reported in certain Australian states, France, Portugal, Spain and the UK. Most of these models are not specifically PV-oriented, but apply for all distributed power systems. At these low buy-back prices there is little incentive for consumers to purchase a PV system unless it directly offsets power purchases at the retail price. At present, the high installed price of a typical grid-connected system, reduces the likelihood of success for such low-level remuneration schemes.

Unsurprisingly, the models showing the highest level of subscription proved to be those offering the highest level of remuneration for bought-back energy. In fact, of the seventeen reported models, only four were considered to be 'successful': in each of these cases the buy-back rate was far higher than the retail electricity price, with the most successful models - those practised along the lines of the German 'Aachen model' and the Swiss experiences at Burgdorf - applying buy-back rates of around five times greater than the grid price. The long-term advantage of such rate-based incentives is that they focus consumer attention on total-system energy production, which redirects priorities towards, for example, improvements in inverter efficiency and system design.

In addition to identifying high buy-back rates as having a major bearing on the development of PV grid-connected applications, the study also calls for models to be based on energy rather than power production and on total production costs rather than surplus energy.

Although public opinion is largely favourable towards PV, there is a need for publicizing the viability of such models to attract essential cross-utility and government support.

Further information can be obtained from the national representatives of Task 1.

Value placed on PV energy in the reporting countries

'Importance' of PV energy	Buy-back Ratio (compared to retail electricity prices)	Country
Very important	» 5 - 6	Germany, Switzerland
	» 2 - 3	Italy
	» 1	Japan, Netherlands (CHE and AUS in some cases)
	» 0,8	Austria
	» 0,5 - 0,7	Australia, Portugal, Spain (NLD in some cases)
	» 0,3 - 0,4	France and United Kingdom
Not important	0 or no models	Korea, Sweden, Denmark, Canada

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