Help: I'm getting conflicting advice about split aspect solar PV and inverters
Posted by Cathy Debenham on 10 April 2012 at 9:01 am
Q: I have had 3 consultants for solar PV and now I am confused. I already have a 2kW system, and wanted to get another 3kW installed. One company said they could not do it, the next said I would get rid of my bill and was going to do split aspects on one inverter. The third one said that I couldn't do split aspect with out having 2 different inverters, and that it would still have a power bill.
A: First, you won't get rid of your power bill unless you invest in a bank of batteries to store the power you generate for use when the sun is not shining and at night. Unless you live somewhere really remote and off grid, this does not make sense for most people. I'd be quite suspicious of anyone who told you that you would.
The system works so that when the sun is shining, you use the electricity generated by your panels, and any excess is exported to the grid and used by your neighbours. At night (and on cloudy days) you will continue to buy electricity from the grid.
The trick to getting the best out of your solar panels (or any other form of microgeneration) is to use as much of the solar electricity that you generate as possible, so that you don't have to buy as much from the grid. To do this, make sure that you do discretionary things like run the washing machine or Hoovering when the sun is out and the panels are generating.
As far as the inverters are concerned, there are three options for a split aspect system: A single inverter with two separate maximum power point tracking inputs; two separate inverters or micro inverters fitted on each solar panel. Click the links above to read more about each of them.
The third thing you need to consider is that by adding a 3kW system you will put yourself in the next bracket for the feed-in tariff, and will get a lower rate of feed-in tariff as a result. New installations of solar of 4kW or less will get 21p per kW, but because yours will be calculated to be 5kW in total, you will get 16.8p per kW on the new 3KW system. The export rate will be 3.1p per kW on both.
With a bit more knowledge under your belt, you may want to get a couple more installers round to quote. You can find local solar installers in our directory, and read what their existing customers have to say about their professionalism and customer service.
If you have a question about anything in the above blog, please ask it in the comments section below.
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