Friday, February 11, 2011

What makes a great PV solar system?

Ask your salesperson if they are familiar with NEC 690.   If you get a "deer in the headlights look", better switch to a lighter subject.

Bottom line is that an advanced generation system is going to be bolted to your roof.   We study the NEC (National Electrical Code), and follow the HECO specs also.   But code compliance isn't really "good enough".   The NEC looks like the image below, click for a larger view.   It has 14 pages related to PV, and 822 pages overall.   But a great installation needs more.   See below.

 Now take a look at this picture, what do you see?   Seriously, look at it, observe it.

Shingles, sure and panels and rack.   What about the wires?   All nicely secured and tucked away.   And here is my point.   What separates the real deal  from the "just jumped into the business cause our work was slow" crowd, is a lot of things, but a critical one is wire management.   

You don't want wires hanging down, blowing in the wind, chafing your roof, grounding out.   You want a strong rack with solid water sealing supports, and great wire management.   You want solid engineering, high wind uplift, large beefy stainless lag bolts.   And you want good return on investment.Talking to some solar companies?   Ask the company representative about their wire management techniques.   If all you get in response is--we used trained professionals in accordance with NEC codes, well then you might want to know more.   Because the NEC allows contractors to drape a power wire up to  four feet unsupported between panels or rails.   And that wire might only be 3 inches from the roof to start with.   So in order to maintain the tension to keep it from sagging down over time, they have to stretch it tight against the panel junction box and the MC4 or MC3 connectors.   That's bad, all bad.   Instead we use a rack system that supports the cable directly, and when we cross over we will support the wire in the middle usually no more than 2' on a 4' crossing.   

Why?  Because great wire management is what keeps your system working safely for decades.   

We put our money and labor into quality, not into sales fees.   When getting a solar estimate ask the sales person:

1) Are you familiar with NEC 690?
2) What methods do you use for wire management?

Tuesday, February 1, 2011

Energy Fundamentals in 4 Easy Charts