If you like the idea of investing in renewable energy, but think that installing solar panels sounds like too much aggravation, green electricity firm Ecotricity has just launched a bond promising to pay a 6% return.

"Ecobond two" aims to raise £10m and allow people to share in the benefits of the green energy revolution "without needing to stick anything on their roof". The bond has an initial four-year term and will pay an annual rate of interest of 6%, rising to 6.5% for Ecotricity customers. The latest offer is a repeat of the firm's Ecobond one, launched in October last year, which was oversubscribed by 50%.

The bonds are open to UK-based individuals, companies, trusts and charities and the minimum investment is £500. Issuing them allows the company to bypass the banks, raising cash that will be spent on developing its wind-farm capacity.

Ecotricity says that for investors, the bond is a great alternative to feed-in tariffs, though unlike that scheme, the income is taxable and is not inflation linked. It should also be noted it is not without risk. Investors putting the same money into a top-paying bank/building society four-year fixed rate savings bond would currently get a little over 4%, but if the worst happened and the bank went bust, the first £85,000 of your investment would be protected. In the unlikely event Ecotricity folded, savers would be likely to lose some or all of their investment.

If you want a more traditional savings account, some top payers have been launched this week. Close Brothers Savings has a "Premium Gold" two-year fixed rate account paying 4.25% on a minimum investment of £10,000.

Meanwhile, Kent Reliance has a one-year fixed rate bond that pays 3.6% with a minimum investment of £1,000. There is no minimum age – the account can be operated on behalf of a child – and withdrawals are allowed, but are subject to a penalty of 180 days' interest on the amount withdrawn.