Self-Consumption vs Export: Why Using Your Own Solar Wins

A kilowatt-hour you use yourself saves the full retail price; a kilowatt-hour you export earns whatever your scheme decides. As export rules tighten worldwide, that gap now drives system sizing, battery decisions and payback more than panel prices do.

Every kilowatt-hour your panels produce goes one of two ways: it is consumed inside your home the moment it is generated, or it flows out through the meter to the grid. For years, generous net metering made the distinction irrelevant, since both were worth the same. That era is ending in most markets, and the single most important number in modern solar economics is the gap between what you pay for grid electricity and what you are paid for exports.

Why a self-used kilowatt-hour is worth more

When your dishwasher runs on solar power, the utility never sees that kilowatt-hour, so you avoid the full retail price, including the energy charge, network charges, levies and taxes bundled into it. When you export instead, you receive only what your compensation scheme pays, which ranges from full retail credit down to nothing at all. The annual value of a system is therefore:

When export rate equals retail rate, the split does not matter. When the export rate is a quarter of retail, or zero, the split dominates everything.

A tour of export regimes

Details matter within each row. Spain nets surplus against the energy portion of the bill monthly, and any excess beyond that is simply forfeited. UK SEG rates are set competitively by suppliers, so shopping around can triple the export rate. California credits exports at hourly avoided-cost values that are low at midday and briefly high on summer evenings, which is exactly why batteries reshaped that market.

What your regime means for sizing

Under full retail credit, the grid behaves like a free, perfectly efficient battery, so the rational move is to size the array to cover roughly 100% of annual consumption, and self-consumption timing barely matters. Under reduced export rates, oversizing produces cheap exports, so the economic optimum shifts toward covering daytime consumption, with any capacity beyond that justified either by a battery or by genuinely low panel costs. Under zero export, capacity beyond your daytime load plus storage is simply wasted. Start with the system size calculator to establish your baseline, and if you are in California, the NEM 3.0 battery calculator models the hourly export values directly.

Worked example: the same 10 kWh under three regimes

Suppose your array produces 10 kWh on a given day, your home directly consumes 4 kWh of it, and retail electricity costs 0.30 per kWh in your currency.

Identical hardware, identical sunshine, and a 2.5x spread in value. Now shift load so the home uses 7 of the 10 kWh directly. Under net billing the day is worth (7 × 0.30) + (3 × 0.075) = 2.33, a 41% improvement achieved with timers rather than equipment. That is the whole argument of this article in one line: under reduced export rates, behavioural and control changes are often the highest-return investment available.

Practical ways to raise self-consumption

• Run heavy appliances at midday. Dishwashers, washing machines and dryers on delay-start timers move 2-4 kWh per day into solar hours at zero cost.
• Put resistive heating on timers. Electric water heaters (geysers) and pool pumps are the classic wins; a geyser is effectively a cheap thermal battery storing 3-5 kWh as hot water.
• Charge the EV from surplus. A smart charger that follows excess solar can absorb more surplus than everything else combined; model it with the EV solar charging calculator.
• Add a battery. Storage shifts evening consumption onto daytime generation and is the only tool that works after sunset.

Live case: the Netherlands salderen sunset

The Netherlands has run one of the world's most generous schemes, salderen, under which annual exports offset annual imports one-for-one. That scheme ends on 1 January 2027. Afterwards, exported energy earns only a feed-in payment from the supplier, a fraction of retail, and several suppliers have already introduced feed-in fees for solar households. Dutch owners who sized systems to 100% of annual use under salderen will see payback lengthen unless they shift consumption or add storage, and the Dutch market has become a natural experiment in everything this article describes. Model the before-and-after with the Netherlands solar calculator.

An honest note on batteries

A battery bought purely to raise self-consumption earns, per cycle, roughly (retail rate minus export rate) × usable capacity × round-trip efficiency. At a 0.22 spread, a 10 kWh battery cycled daily at 90% efficiency earns about 2 per day, some 700 per year, against a hardware cost that may be several times what ten years of that saving covers. Sometimes the numbers work, especially with high evening rates or time-of-use spreads on top; sometimes they clearly do not. The battery must be judged on its own payback, not bundled invisibly into the solar business case. Run the battery payback calculator before you sign.

Common mistakes

• Assuming the export rate equals the retail rate because a salesperson said net metering when the market actually runs net billing.
• Sizing to 100% of annual consumption under a reduced-export regime and expecting the payback that only full net metering delivers.
• Valuing battery-shifted energy at the full retail rate while ignoring 8-12% round-trip losses and battery degradation.
• Extrapolating a sunny-week self-consumption figure to the whole year; annual figures are always lower than summer snapshots.
• Forgetting fixed grid charges, which no amount of self-consumption removes while you remain connected.
• Ignoring scheme change risk: regimes have been cut retroactively for new customers in many markets, so favourable current rules argue for locking in soon, not for oversizing.

Frequently asked questions

What self-consumption percentage is typical without a battery?

Most homes land between 20% and 40%, depending on daytime occupancy and system size relative to load. A small system on an all-day-occupied home can exceed 50%; a large system on a house empty until 6 p.m. can fall below 20%. Load shifting with timers typically adds 10-15 percentage points at almost no cost.

Is full 1:1 net metering disappearing everywhere?

The clear global trend is toward reduced export compensation: California moved to NEM 3.0 in 2023, the Netherlands ends salderen in 2027, and many markets launched directly with net billing. Some jurisdictions still offer retail-rate credit, and existing customers are often grandfathered for a period, but new installations should generally be planned assuming exports are worth well below retail.

Does a battery always make sense under NEM 3.0 in California?

Often, but not automatically. The combination of low midday export values and high evening time-of-use rates creates an unusually large spread, which is why most new California systems include storage. Whether it pays for a specific household still depends on rate plan, battery price and usage shape, so model your own numbers rather than assuming.

Should I install a smaller system if my export rate is poor?

Usually the optimum shifts smaller, toward covering daytime load, but not always dramatically: if panel costs are low, even cheaply compensated exports can justify extra capacity, and future electrification such as an EV or heat pump raises daytime demand. Size for the consumption you will have, then let the export rate decide the marginal panels.