You did your homework: you asked for three quotes. Now it's Tuesday night, you have all three PDFs open on your phone, and the uncomfortable feeling of looking at the same thing three times. Similar panel counts, prices that aren't far apart, and no tool to decide with other than the final price.
Choosing the cheapest seems reasonable. Sometimes it is. The problem is that you can't know that without opening all three, and opening them doesn't require being technical. It requires knowing what to ask.
These are the six differences that usually hide behind similar prices.
1. Do all three start from your consumption?
The first question isn't about the equipment, it's about method. Who asked you for bills? Who asked when you consume, whether you're planning to add air conditioning or an electric car? Who looked at the roof or requested a visit?
A quote made without that data is a price, not a proposal. It may be a good price, but the panel count came from an average case, not from your home. When one quote differs from the other two in size, the explanation is usually here, and it's easily resolved: send your bills to whoever sent it.
2. Which inverter, and not just which brand?
The inverter determines the system's day-to-day behaviour, and it's where quality varies most. Three things to verify beyond the brand:
- The capacity and the type. Is it pure on-grid, or hybrid with the option to add batteries later? If you have that idea for the future, this line decides it: changing it later is expensive.
- The real warranty, in years, and who honours it in Argentina. Is there a local representative, or is the warranty an email to a server on another continent?
- The monitoring. Will you see how much you're generating from your phone? Is the app included and configured, or is it a "you can" that never materialises?
3. What exactly does the installation include?
This is where the biggest and least visible price differences live:
- Mounting structure: included and suitable for your roof?
- Electrical protections and distribution board: included? This is the line where cutting corners goes unnoticed on day one and is very much noticed on the worst day
- Cabling, conduit and full labour, or are there "extras to be assessed on site"?
- The utility paperwork: do they handle it, support you through it, or is it your problem?
The phrase "turnkey" is not a specification. Ask for the breakdown in writing. The three quotes only become comparable once they include the same things.
4. What do they promise it will generate?
All three will tell you how much you'll save. Compare the promises against each other: if two state a similar number and the third promises considerably more with the same roof and the same panels, the calculations most likely use different assumptions. That's why the important figure isn't the final number but the assumptions behind the number, which are what later meet the actual bill.
The reverse question is worth asking too: "what assumptions is this saving calculated on?". The answer tells you a lot about the supplier, sometimes more than the number itself.
5. Who answers afterwards, and for how long?
The equipment comes with a factory warranty. But the installation, the work done on your roof and your distribution board, is warranted by the installer, and that varies enormously.
Concrete questions: how many years of warranty on the workmanship? If the system stops generating in year two, who do you call and how soon do they come? Has the company been in the field for years, and are there customers you can ask?
A warranty is worth what the person signing it is worth, and how long they've been signing them. Track record and customers who can give references are part of the proposal's value, even if they don't appear as a line in the PDF.
6. What do they hand over at the end?
It looks like a bureaucratic detail and it's a right of yours: the system documentation, manuals, warranties with serial numbers, and so on. There's a whole article on this, but when comparing it's enough to ask: "what documentation do you hand over at closing?". Whoever is in the habit of providing it names it without hesitating.
Your checklist for the two-minute table
Draw a table six rows by three columns and fill it with what each quote says, and with what it doesn't say:
- Did it start from my bills and my roof?
- Inverter: type, local warranty, monitoring included
- Breakdown of what's included, in writing
- Promised generation and its assumptions
- Installation warranty in years, and who attends
- Closing documentation
The empty cells are information: each one is a question to ask before deciding. Once the table is complete one of two things will happen: either all three are comparable and price decides fairly, or you discover you were comparing different things at similar prices. Either way, you decide knowingly. Which was the point of asking for three quotes.