Just suppose that governments issued interest-free loans for the installation of solar panels on non-industrial buildings. Here in Sweden one can apply for a 30%* contribution towards the cost of an installation but the sum allocated for such contributions is limited, so that late applicants run the risk of making their investment and then finding that the fund is empty when it is time for pay-out.
Imagine instead that, instead of a contribution, one could apply for an interest-free loan for a period of, say, ten or fifteen years. The loan could be associated with a particular building so that, if the owner moved, the new owner would take on the loan.
Since the money is a loan and not a contribution, repayments under the system renew the fund itself, so that no limit is necessary on the total sum involved. One could go further, and allow the government to arrange the - duty free - import and sale of equipment through, say, a department of the ministry of energy.
I can imagine that such a scheme would increase the introduction of renewable energy manyfold. And why limit it to solar power? There are, of course, fewer buildings which are suitable for wind power, but why not include this source of renewable energy also.
* There are indications that in 2019 the size of contributions is to be reduced to 15% and the sum allocated for this purpose reduced by half which would be a shame.