# Commercial solar and PPA jargon glossary: the key terms a business owner meets, in plain English

This glossary explains the commercial-solar and PPA terms a UK business owner meets most often, grouped into funding, technical and measurement terms. It covers PPA, hire purchase, kWp, kWh, DNO, G99, inverter, self-consumption, export and MCS, so you can read a proposal or contract without stopping at the jargon.

## Funding terms

PPA (Power Purchase Agreement): a contract where a funder owns the solar system and you buy the electricity it generates at a fixed rate per kWh, guaranteed at least 30% below the grid price, with no upfront cost. At the end of the roughly 20-year term the system becomes yours for £1.

Hire purchase: you pay in instalments and own the system once payments finish. Leasing: you pay to use the equipment over a set term. CapEx: you buy the system upfront and own it from day one. Each route has different cash-flow and accounting effects, so take advice.

Introducer: a business like us that connects you to funders and installers without being the funder or the installer. Our service is free, and we may earn commission from a partner.

## Technical terms

DNO (Distribution Network Operator): the company that runs the local electricity network your site connects to. G99: the engineering rule set for connecting a generator above a certain size to the grid, which usually needs DNO approval before switch-on.

Inverter: the unit that converts the direct current from the panels into the alternating current your building uses. MCS (Microgeneration Certification Scheme): a quality standard for smaller installations and their installers.

Self-consumption: the share of your solar generation you use on site rather than exporting. Export: electricity you send to the grid because you are not using it at that moment.

## Measurement terms

kWp (kilowatt-peak): the rated output of the system under standard test conditions, used to describe its size. kWh (kilowatt-hour): a unit of energy, and what you are billed for. A 1 kW load running for one hour uses 1 kWh.

MWh (megawatt-hour): one thousand kWh, often used for larger sites and for REGO certificates. Load: the amount of power your site draws at a given moment.

Half-hourly data: the record of your consumption in 30-minute blocks, which a good proposal uses to match system size to how and when you actually use power.

## Frequently asked questions

**What is the difference between kW and kWh?**

kW measures power, the rate at which electricity is used or generated at a moment. kWh measures energy, the amount used over time. A 5 kW system running for two hours produces about 10 kWh. Your bill is in kWh.

**Do I need to understand G99 to get solar?**

Not in detail. G99 is the grid-connection rule your installer and the DNO handle for larger systems. What matters to you is that approval can take time, so it is worth starting the process early. A good installer manages the paperwork.

---

Source: [Commercial solar and PPA jargon glossary: the key terms a business owner meets, in plain English](https://ppafunding.com/guides/commercial-solar-and-ppa-jargon-glossary) · Author: PPA Funding team · Updated: 2026-08-03

PPA Funding is an independent introducer operated by DVC Group Ltd (Companies House 10462808), Shrewsbury — not the funder, the installer or the maintenance provider. The service is free to use; a commission may be earned from a partner at no extra cost. Content is educational and is not financial or tax advice.