Grounding of solar system

mbu

Im not sure if this question was ever asked but could not find it on previous threads. I have a 2400 solar panel array on a corrugated roof ie 6 x 24 v250w in 3s2p and 6x 12v150w 6s . the two groups are in the same corrugated roof but in two different locations and each has its own mppt cc.I want to ground the system.my idea is to run a single yellow household earth wire from any part of the metal roof to an earth rod buried just outside the house. i also plan to connect the lead neg terminal of my 48v battery bank to the same earth rod and to also connect the earth of my 5kva invertor to the same earth rod.will this work in terms of lighning diversion and allowing the circuit breaker to trip when there is a shot circuit?

Estragon

On grounding the battery negative, you may want to check the manual for your charge controllers as some make the ground bond as part of a DC ground fault protection system.

As for using the metal roof for a pv to ground connection, I can see a couple of potential issues. If you need to follow local electrical code you may find it isn't allowed. There would be a mechanical connection between the panels and racking, racking and roof, roof and ground wire, and ground wire and rod. All of these connections are potential failure points in the ground path, and the roof connections in particular will be prone to galvanic corrosion between the steel/zinc and aluminum racking/pv frame, and the copper ground.

Lightning protection is probably never 100% effective without taking some pretty extreme measures. Grounding the roof as well as a separate pv ground wouldn't hurt IMHO, but won't be 100%. If lightening is likely, I'd also use something like Midnite SPDs.

mcgivor

This article may shed some light on the difference between grounding  (earthing) and bonding 
http://electrical-engineering-portal.com/what-is-the-difference-between-bonding-grounding-and-earthing
As far as lighting is concerned SPD devices may help from an indirect strike, but a direct strike is something entirely different, the  path it takes is entirely up to where it chooses to go, it can actually exit a conductor if it finds a path of less resistance.

MrM1

Estragon said:

Lightning protection is probably never 100% effective without taking some pretty extreme measures. Grounding the roof as well as a separate pv ground wouldn't hurt IMHO, but won't be 100%.

Would that separate PV ground  - I assume you mean Grounding Electrode (aka rod) - be bonded to main house Grounding Electrode?  Creating a Grounding System?

Estragon

Yes, by separate I was thinking of a ground wire attached to panels using WEEB clips or other approved connector running directly to the main ground rod (as opposed to using the metal roof for part of the run).

MrM1

Ok Thanks

heelell

Solar energy can be much cheaper in the long run than drawing power off the grid and having to pay for it. While solar energy might be expensive to set up on a large scale if you want to switch over you entire house, the overall cost of running solar power is cheaper – and this warrants the expense of the set up for many people who realize how much money they will save when they don’t have to pay a weekly or monthly bill for their electricity usage.

Solar Energy Output

Solar energy output varies on the size of the panel that you have installed – and how many panels. The strength of the output is generally measured in voltage and wattage – and you should speak to a professional in solar panels when you want to know which to buy. This will all depend on your individual power consumption – and how much ground you’re hoping to cover. There are solar panels available in various sizes – from small ones that can charge a phone to larger ones that can run an entire house. All depending, of course, on what you need.

mcgivor

You obviously miss the point of storage, the game changer, if one needs no nocturnal energy, then perhaps yes, but in reality energy is required after the sun sets, storage offsets the gains at a greater expense than what most grid providers can supply, additionally the storage has a limited lifespan, requiring replacement, as do the electronic components which convert the DC to the required AC needed to power most commonly used appliances. Therfore it's incorrect to paint a picture of solar energy being free, green or inexpensive, it's none of these, I'm offgrid for reasons of lack of grid supply, not for economical purposes, as most who are in the same situation would agree. Naturally if the reference is to grid tied systems the results would be different, the all important feed in tariff determines the return on investment.