If you lock your money in any asset, whether solar panels or a house, you're taking a bet on the future value of the asset. That, naturally, is a downside. As compared to investing in a fund of some kind that invests in a diversified manner across different forms of renewable energy like solar and wind. Then, if solar prices go down in peak hours, your investment in wind will protect against that to some extent, as opposed to putting all your eggs in one basket.