Two quotations for "5 kW solar" can differ by a large amount, and the cheaper one is not always the better deal. The only way to compare fairly is to put the same items side by side and check what is included. Here is a simple method.
Key takeaways
- Compare the same system size, not just the total price.
- List brand, model, quantity and warranty for every major item.
- Look for what is missing: mounting, cables, protection, net metering, transport, installation.
- Ask each company to explain any large difference.
1. Make a comparison table
Put each quotation in one column and list the same rows: panel brand and model, number of panels, total panel power, inverter brand and model, battery (if any), mounting structure material, cables and protection, installation, net metering support, warranty and service. A quotation that leaves a row empty has either left something out or hidden it in a vague line.
2. Compare the main equipment
Panels and the inverter are the biggest cost. Check the rated power of each panel and the total, the inverter's rating and number of MPPTs, and the warranty on each. A system with more panel power than inverter power is normal and can be good design, but the ratio should be explained. See how to read a solar panel datasheet.
3. Compare what holds it together
Mounting structure, cables and protection are where cheap quotations often save money. Ask about the metal and its coating, the wind rating, the cable type and size, the DC and AC protection and the earthing. A thin structure or undersized cable will not show up on day one, but it will in a storm or a few summers later. See solar mounting structure guide.
4. Compare the services
Is installation included? Is transport? What about net metering paperwork, commissioning, training and a first service? Who do you call if something stops working? Our questions to ask before you buy has a full list.
5. Compare the payment and the timeline
Check the payment schedule, the time to deliver and install, and any penalty or condition. A very large advance with a vague delivery date is a risk.
6. Do not decide on price alone
The total price matters, but so do quality and service over 10 to 20 years. If one quotation is much lower, ask why. Sometimes there is a good answer, such as a different panel brand; sometimes an item has been left out.
Next step
Send us your other quotations and ask us to compare them with ours; use the quotation form or the contact page.
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