From £70 a Month to £3: How a Domestic Solar + SEG Install Rebalanced Keith's Bills

The starting position

Keith is a domestic homeowner who, like a lot of households we speak to, had watched his energy direct debit creep up year after year without a clear sense of what to do about it. "Before we had the solar, we were paying an average of 70 quid a month," he told us when we revisited the install eight months in.

That £70 a month figure was the baseline we designed against. The brief was simple: bring the day-to-day draw down materially, and make sure any surplus generation was monetised rather than given away to the grid.

What KMM specified and installed

We installed a domestic rooftop solar PV system sized to Keith's usage profile, then handled the Smart Export Guarantee (SEG) registration so generation he didn't use on-site became a paid export rather than a free gift to the supplier. The SEG account was set up with British Gas, which is the export tariff Keith chose to sit alongside his import contract.

The work covered design, installation, commissioning, MCS paperwork and the SEG application end-to-end. Keith didn't have to chase the supplier or work out the export metering himself - that's part of what a consultancy-led install is for.

The result eight months on

The drop in spend was immediate. "Straight afterwards it dropped down to 3, 4 pound a month," Keith said. From a £70 monthly baseline to a £3-£4 monthly bill is roughly a 95% reduction in what he pays his supplier for electricity - and that's before factoring in the export side.

The SEG side took a little longer to start paying out, as it always does while the supplier processes the meter readings and confirms the tariff. "As soon as we started selling it... we made the first quarter of selling it, so we only got to about a month and a half of generation where we got 70 pound back from British Gas," Keith said. In other words, in roughly six weeks of export generation he earned back the equivalent of one full month of his old electricity bill.

Generation credits build through the high-sun months, so by September and October the export income was running consistently. "It was brilliant," Keith said of watching the balance move in his favour for the first time. "The up and lowering is just wonderful."

Why this works for domestic households

Keith's case is a clean example of the two-sided economics every domestic solar install should be designed around. First, you displace import electricity at whatever your unit rate is - that's where the £70-to-£3 monthly saving comes from. Second, anything the system generates that you don't use on-site becomes a paid export under SEG, which most major suppliers (British Gas included) are obliged to offer.

What makes the difference between a good install and a mediocre one isn't the panels - it's whether the system is sized honestly to the home's load profile, whether the SEG paperwork is filed correctly, and whether the homeowner is shown how to read the numbers afterwards. Keith now checks his generation and export figures regularly: the addictive bit, as he put it, is watching the numbers move.

Talk to KMM about your own install

If your monthly electricity bill is sitting in the £60-£120 range and you have a suitable roof, the same pattern Keith saw - heavy reduction in import spend plus a quarterly SEG payment from your supplier - is achievable on a domestic install. We'll model it against your actual usage, not a generic assumption.

Book a fully funded survey and we'll quote the system, the expected import saving and the SEG export income before you commit to anything.