Maintenance is typically keeping the panels clear of too much debris (dust, dirt, leaves, etc). Depending on where you live, simply hosing the panels down with water every few months is sufficient. Here’s an article on 1BOG about solar monitoring and maintenance.

I have some questions about the longevity of solar systems. it appears that most systems are guaranteed for about 20 – 25 years. but what happens after that? would you have to purchase a whole new system?

what type of maintenance is necessary to maintain the system?

Its interesting to compare module efficiency, but in most cases, it’s little more than an academic exercise, as long as you are comparing the PTC or CEC ratings, and not relying on the STC ratings that look more favorable.

There are only 2 conditions where the module efficiency matters for residential installations:

1. Limited mounting area requires a more expensive, higher efficiency module to allow the desired array to “fit” into the available space. In other words, you need a 5 kW array, and only 4.6 kW would fit with the lower efficiency modules, so you decide to purchase the more expensive option to reach the 5 kW goal.

2. If there is a big difference between the STC and the PTC, you should figure out expected production, and compare price quotes based on that. Solar modules and even installed systems are sold by the Watt, just as chicken is sold by the pound (or kg). Usually the STC is the figure used to price a system at, say, $5.50/watt. Comparing the cost to the more realistic PTC or CEC numbers would give a better representation of which offer was the best value.

There is no sense in a potential solar customer waiting until the efficiency reaches some particular level — a 4 kW system will make the same amount of power at 35% efficiency as at 15% — it just takes up less room to do the same work.

Clear skies,

Brad Vietje
Green Works Solar Store
Groton & St. Johnsbury, VT

I believe your instincts are correct. There seems to be a problem with the system. You should contact your installer, inform them exactly what you’ve written here: mainly that the peak ratings have not been higher than 3.1 kW for the first month. This is about 69% of the 4.5 kW rating, when you should be maxing a lot closer to 95% peak power readings (or ~4.2 kW).

You can check other solar pv output data at http://www.pvoutput.org. Here is an example 4.464 kW system with Suntech panels for your comparison.

Thank you for describing your situation so well. Please, let us know the solution to your issue when it is found. Though most pv systems should work without a hitch from the start, your situation could be helpful to future pv system owners.

Yours in solar,
Shawn

I have just had a 4.5kW system installed by a professional company in Australia. The system uses 20-Suntech 225W panels and a 4.2kW Aurora Inverter.

We have not seen a Peak Power reading greater than 3.1 kW on the inverter meter since installation one month ago. This is despite perfect conditions with with clear skies and the sun directly overhead. Ambient temperature was noted to be low, 20-25 degrees when the observations were made at mid-day. The panels are inclined at 30 degrees and face directly north (optimum orientation conditions). Our lattitude is approximately 37 degrees south and there is no shading on the panels.

My instincts tell me that there is a problem with the system due to the low peak power readings seen. Given that power generation conditions are excellent, what percentage of the advertised 4.5kW should I be seeing at the inverter meter.

Suntech guarantee their panels to have 95% of rated output in the initial years of their life. Is the lower rated 4.2kW inverter the problem? For your information, I have compared readings on the same days with a neighbour who has a ten year old system. He reports 85% power generation of his system’s rating

Your advice is appreciated.

Paul.