12 questions to ask a solar or inverter installer
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A good installer will be glad you asked these. A vague answer to any of them is a reason to get another quote. Use the calculator first so you know roughly what size to expect.
About the design
1. What load did you size this for? They should be able to say which appliances, how many running together, and for how many hours. If they quoted a “5 kVA package” without asking what you want to run, the size is a guess.
2. What is the inverter’s continuous output in watts, and its surge rating? Not the kVA on the box: the real output in W or kW, and how much surge it handles for how long. See kVA vs kW.
3. How much usable battery energy will I have? Ask for kWh, the battery chemistry, and the depth of discharge they designed for. 10 kWh of lead-acid at 50% gives about 5 kWh of usable energy. See lithium vs lead-acid.
4. How long will the battery run my essentials? They should give hours for your actual load, not a general claim.
5. How many watts of panels, and what month did you design for? A system sized for the sunniest month will fall short in the dullest one. Ask what peak sun hours they assumed and compare with your city’s figures on our locations pages.
About the equipment
6. Which brands and models, exactly? Get model numbers in writing for the inverter, batteries, panels and charge controller, so you can check the data sheets yourself.
7. What warranties come with each part, and who honours them? Ask how long, what is covered, and whether a claim goes through the installer, a local distributor or an overseas manufacturer.
8. Is the charge controller MPPT or PWM? MPPT controllers harvest noticeably more energy from panels, especially with longer cable runs and higher panel voltages. Many hybrid inverters include one.
About the installation
9. What protection is included? Fuses or breakers between battery and inverter, DC isolators for the panels, surge protection, and correct earthing. Battery cables carry large currents and must be properly sized.
10. Where will the batteries and inverter go? Batteries need shade and ventilation, away from living areas for flooded lead-acid types. Inverters need airflow. Panels need a shade-free spot, ideally facing the equator.
11. How does the changeover work? Will the whole house switch over, or only selected circuits? Is there a bypass switch so the house can run from the grid if the inverter fails?
About after-sales
12. What happens when something goes wrong? Ask about response times, whether they will check the system after installation, and whether they provide monitoring, such as an app showing battery level and solar output.
Red flags
- A price without a list of components and model numbers.
- Sizing done without asking about your appliances.
- Batteries promised to last “forever” or “20 years” with no data sheet.
- Pressure to pay in full before installation, or before you have checked the equipment.
- No mention of fuses, breakers or earthing.
Get at least two quotes, compare the usable battery kWh, inverter watts and panel watts side by side, and ask each installer to explain any difference from the others.