In this paper we study a community or firm considering to diversify its investment in two distinct renewable energy technologies, namely wind and solar PV electricity. We assume technological learning curves as a function of cumulative capital investment. A real options approach is applied as it takes into account uncertainty about prices and learning, as well as irreversibility associated with investment decisions. We investigate three different cases, dealing with uncertainty about future electricity prices, and uncertainty about the speed with which learning drives the costs of wind and solar electricity down. We assess the minimum threshold for the stochastic price and the maximum electricity production cost that makes it optimal for the firm to invest in the two technologies. The results show that the learning rate affects the option to invest in but reducing critical threshold for exercising it. The greater the amount of capital invested, the more learning stimulates earlier exercising of the option to invest. The firm will then anticipate the option to invest and exercise it for lower critical threshold values if all capital is invested in one technology. If capital investment is diversified, the option should be exercised at a higher critical threshold. More uncertainty in energy prices or technology costs postpones the option to invest. Although investing in both solar and wind may be profitable under particular conditions of price and cost uncertainty, the theoretically optimal strategy is generally investing in only one technology, that is, solar or wind, depending on their relative initial costs and learning rates. This suggests that the practice in most countries of diversifying renewable energy may reflect a mistaken strategy.

在本文中，我们研究了一个社区或公司，考虑使其在两种不同的可再生能源技术（即风能和太阳能光伏发电）上的投资多元化。我们假设技术学习曲线是累积资本投资的函数。由于考虑了价格和学习的不确定性以及与投资决策相关的不可逆性，因此采用了实物期权方法。我们研究了三种不同的情况，分别是关于未来电价的不确定性和关于学习将风能和太阳能成本降低的速度的不确定性。我们评估了随机价格的最小阈值和最大的电力生产成本，从而使公司最有可能在这两种技术上进行投资。结果表明，学习率会影响投资选择权，但会降低行使该选择权的临界阈值。投入的资金越多，学习越多，就越早激发投资期权的行使。如果所有资本都投资在一项技术上，那么该公司将预期选择投资并以较低的临界阈值行权。如果资本投资多样化，则应在更高的临界门槛下行使选择权。能源价格或技术成本的更多不确定性推迟了投资选择。尽管在特定的价格和成本不确定性条件下，对太阳能和风能的投资都是有利可图的，但理论上最佳的策略通常是仅投资一种技术，即太阳能或风能 取决于他们的相对初始成本和学习率。这表明在大多数国家，使可再生能源多样化的做法可能反映了错误的战略。