A solar proposal predicts how much electricity the roof could generate. A separate question is how much the connection is allowed to send to the grid at any moment. Those two figures are not interchangeable.
An export limit can affect the way a system operates and the financial assumptions behind a quotation. Ask the installer to explain it in ordinary language before comparing projected savings or export payments.
Find the limit and its units
Check whether the proposal refers to panel capacity, inverter output, an export limit or annual energy. Power and energy describe different things: a limit on instantaneous export is not the same as a yearly generation estimate.
The Energy Saving Trust’s solar calculator guidance notes that export restrictions can reduce exported electricity and payments, and that its estimates assume no export limits. The tool concerns its stated market; use the rules, tariff and connection requirements applicable to your own location.
Ask what the controls do
Have the installer describe the proposed export-control arrangement and what happens when generation exceeds household demand plus permitted export. The answer depends on the system. Do not assume every inverter, battery or control device behaves identically.
A useful question is: “Which part of this estimate accounts for the limit, and how was my daytime demand represented?” A household that is usually empty at midday may use generation differently from one with substantial daytime loads.
Compare scenarios with the same assumptions
For an illustrative comparison, ask for the proposal with the actual export constraint and a clearly stated household-use pattern. If storage is offered, request the extra cost and the assumptions about charging, discharge and usable capacity separately. A battery is not automatically justified simply because a limit exists.
Check that financial projections distinguish imported electricity avoided from exported electricity sold. Those benefits may have different values, and tariffs can change. Treat a forecast as a model with assumptions, not a guaranteed return.
Keep approval and installation responsibilities clear
Confirm who handles required connection approval, commissioning and documentation. Do not change inverter export settings or bypass controls yourself. Use appropriately qualified installers and the relevant network requirements.
Keep the agreed limit and system configuration with the handover documents. The most useful proposal is one that explains what the system may do on a sunny day, what it cannot do, and how those boundaries were reflected in the numbers.