Solar PV scammers on the increaseStuart Reid
We have had a recent upward trend in the number of enquiries from customers regarding direct mail or phone calls that they have received from a handful of national companies.
The usual spiel refers to expired inverter warranties or installers that have ceased trading (even if they haven’t), then they offer a “free health check” for your solar PV system. Many people see through this and don’t go any further, but I have spoken to a lot of people who have let them send round their “engineer”.
The “engineer” usually wears a suit and arrives in a car. He or she then (without any test equipment) tells the unsuspecting householder that their system needs an expensive upgrade. The reasons for this upgrade are always either to significantly increase the system yield, or that the system is no longer working properly.
The most effective sales strategies rely on the most powerful human instincts, in this case greed and fear. If they can’t appeal to one of these instincts they will try the other, and all too often people fall into their trap and place an order with the villains.
The “upgrades” tend to be either solar panel optimisers (usually manufactured by SolarEdge) or a voltage optimiser.
It’s important to note here that solar panels will produce what they produce regardless of what they are connected to. Your inverter is already about 97% efficient therefore there’s little improvement to be had by “upgrading” it.
Solar panel optimisers
In a standard system all the solar panels are connected together in a chain. When connected in this way their voltages add together and depending on the number and type of solar panels, the inverter usually gets between 200 and 500 volts. It then alters the voltage and ‘inverts’ it to a.c. so that it can be matched to your household mains supply. A drawback with the solar panels being connected in this way is that, if any panel is shaded by surrounding objects or excessively soiled, it reduces the overall current in the array, and thus reduces the yield.
Optimisers are devices which are fitted to the rear side of solar panels in order to modify their voltages individually. If a solar panel is producing less than the others in the chain, it will lower its voltage which then increases the current to match the others. In this way optimisers are an effective way to combat the mismatch due to shading or soiling.
However, optimisers are not without their own drawbacks:
- The upgrade is expensive – each optimiser costs around £40 and the inverter usually needs to be replaced at a cost of around £800. A system of sixteen panels therefore costs around £1500 plus labour and VAT to upgrade. Many of these villains are selling such upgrades for £5000 plus. No one will ever recoup that money from increased yields.
- The yield increases are usually overstated – SolarEdge themselves claim “up to” 25% increase in yields with an optimised system. Most system owners will see a rise so small it’s not noticeable. Unless there is severe shading or something wrong with the way the existing system is set up, a rise of 2% to 5% is more likely.
- Optimisers do go faulty from time to time – we know this because we go round replacing faulty ones. They do have a 25 year warranty but can you really expect the installation company to be trading for that length of time? You’ll need to factor in the likelihood of paying to have faulty optimisers replaced.
- Manufacturer stability – Most optimisers require the same make of inverter, and that inverter won’t work without the optimisers. Consideration must be given to what you would have to do if you needed replacement products in the future but they were no longer being manufactured. With a standard system there are no optimisers and you have a wide choice of inverters should you require one.
One of the benefits of staying with your standard solar PV system is its simplicity. When your inverter fails you simply need another (cost circa £800 inc fitting for a typical 4kW system).
PV Voltage optimisers
The purpose of this product is to lower the mains voltage to the inverter as if it does go over 253V for a period of time it will shut down. There are two reasons that this may happen:
Firstly the inverter supply cable may be sized too small which is allowing a voltage rise to occur between the inverter and the household mains. This is easily and cheaply solved by replacing the cable with a larger one.
Secondly, it could be that the incoming mains electricity is too high. Your local Distribution Network Operator (DNO) has a legal duty to keep the supply voltage between 220V and 253V. If the voltage rises above 253V then they are obliged to make alterations to bring it back within the statutory limits. This costs the consumer nothing. Also, if your incoming mains voltage is high then this will shorten the lifespan of electrical appliances. A PV Plus device does nothing to address this.
This device wholesales for £200 or so but these companies charge £1000 for it. Rather overpriced for an unnecessary product.
There are various sites on the web with similar tales: