FAQs and System Troubleshooting

Your solar photovoltaic (PV) system can help you save money in two ways. The first is by reducing your grid imports. When your solar panels generate electricity, it will automatically be fed into your house and cover part or all of your household consumption (if you’re generating enough). When your system produces surplus electricity, it will automatically be exported to the grid. By signing up to an export tariff, you can save money in a second way…

The government’s Feed-in Tariff (FIT) scheme closed to new applicants in March 2019, and there is no automatic registration or payment to small-scale renewable energy generators. However, the Department for Business, Energy and Industrial Strategy (BEIS) introduced the Smart Export Guarantee (SEG) on January 1st, 2020.

All our customers (unless off-grid) should sign up to an SEG tariff where you are paid for your energy exports. As soon as your system is operational, you will be exporting power to the grid but won’t receive payments until you are on a tariff. The system owner alone must register for a SEG tariff via their energy utility supplier/s, Sunlight Future cannot do this. However, as part of your handover pack, we will provide you with the necessary documents, including your MCS certificate and DNO letter.

As batteries and electric vehicle chargers are becoming more and more popular with solar installations, energy suppliers have been updating their tariffs to offer customers attractive time-of-use tariffs in which the price to buy/sell energy varies throughout the day. These tariffs help reduce demand on the grid during peak periods and offer customers better savings by offering cheaper prices during off-peak periods. It is worth doing some research to ensure you pick a tariff that enables your system to maximize your savings

The entire system is designed to be as hassle-free as possible. All panels have a self-cleaning glass surface, so the rain will wash debris from the panels. However, further cleaning may still be necessary and you can have the panels cleaned by commercial window cleaners or other professional solar panels cleaner . Please instruct contractors not to use detergent on the panels and always use non-abrasive brushes.

It is also important to keep track of the amount of electricity your system generates (alongside the weather conditions). This will help you identify any issues with your system and ensure that it is functioning correctly.

Solar panels are capable of producing energy throughout the year. However, the yield does drop in the winter as the sun is lower in the sky and has less energy. Additionally, the shorter daylight hours in the winter reduce the amount of available time the panels can generate electricity.

Solar panels react to the visible light spectrum. This means that if there is enough light to see, there is enough light for solar panels to start generating electricity. However, the stronger the sunlight, the better the performance of the solar panels.

A green light on your solar panel inverter is usually a good sign. It indicates that the inverter is on and either generating electricity or able to do so when the sun comes out.

A red light is probably indicating a warning or fault message. Refer to the inverter manual from the manufacturers website to find out how to navigate the menus to track down the issue. Once you have checked the menus give us a call (0117 3250324) or email and we’ll start the troubleshooting process.

Typically, this light means that the system is currently generating. It is more important which colour the flashing light is (see above).

This means that you are generating electricity. The light will pulse faster the more electricity there is passing through the meter.

If the light on your solar panel generation meter is constantly red, it indicates that there is currently no generation coming from the panels through the meter. This is typically because the light levels are currently too low, and the inverter is in a sleep state. If there is plenty of sunlight, this might indicate that the inverter has either been switched off or has developed a fault. In such cases, it is recommended to refer to the inverter’s manual for diagnostics.

Have you made any changes to your Wi-Fi router recently?

If you have recently made any changes to your Wi-Fi router, you will need to connect all your devices to the new network. Instructions to do this can usually be found on each of the manufacturer’s websites. If you are having issues, it is usually best to contact them before requesting a call-out from us.

Alternatively, it can save time to change your new router’s network name and password to match the old details, which allows all your devices to automatically connect to your new router.

Is the device connected via Wi-Fi Extenders or Powerline Adapters?






Check that all the correct lights are showing on the extenders. Normally, we install TP-Link av600 models, and their led status is explained in this article
. If the powerline LED is not on, then you should turn the Powerlines off and follow the pairing guide
. If the ethernet LED is off, then there may be a loose, damaged or faulty network cable.


Is the offline device connected via a network cable?


Check for loose connections or signs of damage to the cable.

Some inverters, including Solis inverters, are DC powered. This means that if there is not sufficient sunlight, then the inverter will not show any lights or activity.

Ensure that all switches on the inverter, DC and AC isolators, and trip switches are in the on position. More guidance can be found in your handover pack under the START UP / SHUT DOWN PROCEDURE section.

If your battery is not charging or discharging when you would expect it to, there may have been a recent firmware update. You can normally see this on your app. Some systems will undergo a battery calibration after a firmware update. A calibration is where the battery is fully discharged before being charged to full. After this process, the battery percentage (state of charge) should be more accurate.

The default settings for most battery systems are to increase self-consumption as much as possible by storing any surplus solar generation and reducing the demand from the grid. However, many of our customers are on time-of-use tariffs, where the buy/sell prices vary throughout the day. If this applies to you, then you should ensure all the correct settings have been applied on your app. To enable off-peak charging, grid charging may need to be enabled and tariff optimisation/ time-based control should be set up so that you maximise your savings. To do this it is best to refer to the manufacturers websites as they all work slightly differently. Sometimes you need to select your energy tariff, and others require you to manually input time periods/prices.

Some systems, including Tesla Powerwalls, use complex algorithms to make predictions and maximise your savings. This can take into account weather forecast data to predict future solar generation as well as historic usage data to predict your future usage. This allows your battery to only charge up to the right amount based on your usage and, depending on your DNO restrictions, may discharge to the grid during peak times.

Solar panels have a “kWp” rating that tells us their peak power generation. This number is what each panel is expected to generate in perfectly sunny conditions. However, there are a number of factors that affect what they will actually generate. During the hottest summer days in the UK, the voltage of the panels is reduced, and the efficiency of solar panels will actually be reduced by several percent. The orientation and inclination of the panels and any shade on the array will also reduce the performance.

In addition to a total “kWp” rating, your system will have an appropriately sized solar inverter that converts the DC power generated by your solar panels into the AC power that your house needs. The rating of the inverter limits what your system is able to generate, and we typically undersize them compared to the total “kWp” rating of your array. This means that on days with perfect conditions (temperature of 25 degrees C, 1000W per square meter of sunlight, and an Air Mass Density of 1.5), there may be a couple of hours during the middle of the day that your system is not able to generate the peak rating of your array. However, by doing this, the system can ramp up quicker in the mornings and ramp down slower in the evenings, resulting in a fatter power production curve and a higher total generation.

Your Solar PV design report includes a graph of what our simulation expects your system to generate each month. These predictions are only an estimate but should give you an idea of what to expect (they are not guarantees of performance). However, if there are multiple months where your system is significantly underperforming, then you should contact us in case there are any issues that can be resolved.

The battery systems we install use a CT meter device at your incoming supply to measure the energy being imported/exported from the grid. This device communicates with your battery system to instruct how it should operate if it is set up to maximise self-consumption (reduce demand from the grid).

When your PV array is generating more power than your house is currently consuming, then the surplus power must go somewhere. On installations without batteries, this surplus energy is automatically sent to the grid (this is what must physically happen to the energy). In battery systems, rather than sending surplus solar energy as exports to the grid, your CT meter measures this and then sends a signal to tell your battery to start charging at a rate similar to whatever the surplus energy is. This takes a few seconds to start, and so as your house load and solar generation varies, there will always be some exported energy. Similarly, if your house load is not being covered by your Solar PV alone, then the system will be telling the battery to discharge to your house so that the load is fully covered, and you don't need to import from the grid. If your house load then drops, the battery will still be discharging at the same rate, and as the energy must go somewhere, this will be exported to the grid. Your CT meter then measures this energy flow and adjusts the discharge rate of the battery accordingly. Most battery systems come with an app where you can see how your system is reacting to varying loads (turning the kettle on and off is an easy way to do this).