First things first, you are dealing with technology that you most likely are not familiar with, at least not enough to repair yourself. Inverters and panels can break, electrical lines can be damaged, and parts can be faulty. You may not be thinking this is a major issue when deciding what solar company to choose, but that changes quickly after installation.
If you plan on purchasing panels, most solar company DO NOT maintain the panels, but offer a manufacturer's warranty (standard with any panels) for 25 years. This means that the solar company is not held responsible and WILL NOT fix parts unless otherwise specified. If you are planning on leasing or signing up for a power purchase agreement, most solar companies will provide some maintenance, but what level and for how long depend on the solar company. It is very important to find out this information before signing a contract.
Most solar companies will insure their work around roof intrusions for one year, and some will insure their work for longer. Other solar companies will force you to add the solar onto your homeowner's insurance so that if anything happens to your roof, your homeowner's insurance is responsible. This is risky because your insurance will increase and you will be forced to pay the deductible (if you have one) should your roof ever need work.
There are thousands of solar companies out there, but the surprising fact is that most of them are only sales or installation companies for a larger financier. The danger in subcontracting, especially in solar, is in cases of property damage, expectations set at signing, and customer care after installation. Typically, your contract is with the financier and you have agreed to their terms (no matter what your sales person may have said). Remember, if it's not in the contract you signed, it isn't valid. In cases of roof or property damage, the installers are typically held responsible. This is where the first problem occurs. Installers are paid to do installations, so their priority will never be to fix a problem on a previous installation since they will make no money for it. Also, if it's a small company and they go out of business, you may have an even harder time trying to get your problem attended to (remember these panels are supposed to work for 30-35 years).
Most solar companies have a clause in their contract stating that their financiers will take over. What does this mean? You will still pay your bill for a lease or power purchase agreement to this financier, but good luck getting maintenance or repairs on your panels. Unless the solar company has set aside private funds solely for the purpose of their customer's monitoring, maintenance, insurance, and repairs, your system will not be attended to.
Online is a good place to start when researching customer experiences with their solar company. It is important to keep in mind that most happy customers will say nothing, while unhappy customers tend to post on every blog available. That in mind, there is always a grain of truth to every complaint, no matter how exaggerated the customer may have been.