Quote:
Originally Posted by inertia8
Does anyone have experience with micro-inverters being installed? My property has unfortunate amounts of shading from trees in the park next door, which according to a couple of quotes means we'd need micro-inverters to reduce the impact of the shading and is one of the reasons we didn't end up going for it. The tarrif is now 8c/kWh or something so only worth it for removing daytime activities yes?
We have a couple of fish ponds running pumps and air blowers 24/7 which eat up a fair amount of juice and I'm looking into timers or other alternatives being mindful of not killing the bacteria in the filters from long shutdowns etc.
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I attended an energy conference recently and micro inverters were becoming very popular products. Most of the micro inverter systems I saw in the displays were sold as complete with micro inverter/solar panel and wiring already installed. There were also inverters sold separately (about $200 form memory, for 250W micro inverter). There was one company also selling micro inverters for about $60 each
I can see what you want to do in order to avoid tree shading. The panels are usually electrically connected in series, so the voltage adds up but the current stays constant. This is great for keeping the current low, because very thick wiring is required to carry the current (amperage). The problem is when one panel is shaded the entire system drops its output dramatically.
I recall a company selling solar panel efficiency meters and testers to the maintenance industry (very pricey too, about $2,500 for a unit that looked a little bit bigger than a multimeter, with a fancy display)
They were displaying how efficiency drops dramatically even when a small part of the panel is shaded or hidden. As an example, the efficiency of large 190 W panel will drop by 50% if you place a business card on the panel. That is block just a few percent of the panel surface area and the efficiency drops by 50%.
The drawbacks of micro inverters installed on the back of the panels themselves is overheating and therefore losing their efficiency. Also you need to go up onto the roof to replace/repair any faulty micro inverter.
I have heard of people installing banks of micro inverters in the roof cavity or at ground level. Watch fire hazards and regulations if you install these devices in the roof. (not even sure they are legal to install there, with insulation etc). Also you need more wiring and therefore incur higher losses if you remotely install a bank of micro inverters. Advantages are that each panel will operate independently and therefor you do minimise losses if you have shading issues on your property. Also you can buy a few back up micro inverters and replace them easily of they fail.
So far my string of 12 panels (190 W each) have been working very well. If one panel drops its efficiency for whatever reason, then the entire string of 12 panels drops to the efficiency of the underperforming panel. Micro inverters avoid problem and are very cheap these days.
You will need to do the sums, but as I understand it, the more panels you need to install with micro inverters the less economical it becomes compared to a standard single inverter system - but you may not have a choice if you have partial shading problems.
good luck