Living with solar electricity (PV) panels

Who should read this guide?

If you are living in a home with solar PV panels, this guide will give you some general information about what to expect from them and how to get the best out of them. It isn't specific to any particular sort of panel, and it isn't about how to choose them or install them. It does explain some things you should know if you move into a new home that has them.

What do solar PV panels do?

Solar PV panels generate electricity from sunlight. You can use this power in your home, and any left over will be exported onto the grid. If you are receiving feed in tariffs for your panels, your payments are based on how much is generated, not how much is exported, so you can use as much as you like without affecting your payments - this is free electricity. However, whether you use it or export it the carbon savings are the same.

Your PV panel system has three main parts:

  1. The solar panels themselves which will be somewhere on the roof.
  2. The inverter that converts DC power from the panels to AC power for your appliances and the grid. This is usually in an attic or a utility room because it can be noisy. Sometimes there will be more than one inverter and sometimes there are micro-inverters, one per panel, integrated into the panel. In that case there will be a gateway or load center where the power from each panel is combined.
  3. The generation meter that records how much you have generated. This is often close to your electricity circuit box.

You may also have a digital display that gives real time information about how much is being generated at any time. Sometimes this information is exported to a logging service on the internet and you can use a web browser to get at your PV generation data.

How do I know they are working?

PV panels should be generating whenever the sun is shining. If it is not very sunny, they won't generate very much but you should get some even through cloud.

If you have a digital real time display you can check this to see how they are doing. Otherwise, inverters often have an indicator as to how much power is being generated, such as a dial or a flashing LED. Finally you can look at the generation meter. This will usually have a pulse led which flashes for every Wh generated. For example if it flashes 30 times a minute then you are generating 30*60 = 1800W.

Also your meter will have a digital display in kWh that indicates how much you have generated over all time. It is a good idea to check this weekly. The amount of generation per day will vary through the year.

What do I need to do? Is there anything I shouldn't do?

You don't need to do anything except check it is working sometimes. To get the most benefit from it, you can try to shift your electricity consumption to when the system is generating. For example you could run the washing machine or the dishwasher on sunny days and avoid running it overnight or on cloudy days.

You can also get a system to use your spare electricity to heat your hot water tank, if you have one. There are a number of different products for this such as SolarCache, Immersun, and IBoost.

If your system is registered for feed in tariffs you will be asked to read your meter occasionally for the electricity company so that they can calculate your payments.

How much power do your appliances take?

How sunny does it have to be to be to power your appliances from your panels? If you have a real time display you can check how much spare power you are exporting before running them. This table gives a guide as to how much power appliances usually take. However, appliances vary a lot.

ApplianceMaximum power (kW)When
Washing machine1.5 - 2.5mainly when heating water, usually at the start of the cycle
Tumble dryer1.5 - 3.0throughout the cycle
Dishwasher2.0 - 3.0several times especially while drying at the end of the cycle
Vacuum cleaner0.6 - 1.5throughout use
Iron1.0 - 3.0at intervals throughout use
Oven1.5 - 2.5at intervals throughout use
Microwave1.1 - 3.5Check the rating on your appliance and multiply by about 1.4 e.g. to deliver 1000 W it will use 1400 W or 1.4 kW

Why is it making that noise?

The only part of the system that can be noisy is the inverter. This can get rather hot so it has a cooling fan and it is the fan that makes the noise.

What maintenance does it need?

The main thing is to check it is working occasionally, as above. If it isn't, it could be just that the inverter switch has tripped due to a power glitch. In that case you can turn it on again. Otherwise, the most likely point of failure is the inverter and it may need replacing.

The panels should not need cleaning unless you are in a very dusty area or the slope is too shallow for the rain to run off cleanly.

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