The inverter is the heart of a solar PV system, converting the electricity generated by your panels to grid compliant power for use in your home.
The quality of your inverter will affect the performance and longevity of the system substantially. Even small improvements in performance will add up over the 20 year duration of the Feed-In Tariffs.
The inverter either manages individual panels or whole sets of panels (cabled together in series), inverting the power to AC as efficiently as possible. Each installation has unique requirements so we give a lot of consideration to choosing the correct inverter for your project. We install inverters from a reasonably small set of manufacturers – the inverter is the most critical part of system with regard to performance and reliability.
As inverters are the brains of the PV array, new models come with additional features to bring increased value to the homeowner. Most inverters are now internet enabled, giving you full monitoring, performance analysis and diagnostics via the web. With the domestic solar market in the UK and abroad focusing on smarter energy usage using batteries, “smart-switching” and heating controllers, some inverter manufacturers have started to build in compatibility to these applications as standard.
The other advance in recent years is unit-size and performance. Inverters are considerably smaller and lighter, with some 4kW inverters weighing in at under 10kg. As components get more efficient, less heat is produced during operation. In electronics heat is the enemy of reliability. With newer, smarter circuit designs and decades of real-life product experience manufacturers are now making inverters that are longer-lasting by design. At Sunlight Future we consider it essential that to know that we are supplying equipment that is built to last.
After we have done your free survey we model your house and surrounding houses, trees and shading obstacles in our software and produce from this quotes that will work for you. During this process we run simulations to “audition” different inverters and configurations. This ensures that our performance projections are accurate and we squeeze every last drop of performance out of the systems we’ve designed for you.
Once you have received your quote you will probably want to know more about the equipment we have included. The following is a brief guide covering some frequently asked inverter related questions and technical terms:
Although we can supply and fit almost any MCS approved product, we prefer to fit the tried-and-tested models recommended by our system designers and installers. We always match inverters carefully to the panels for each design we produce, so what you see in your quote is likely the model we believe closest matches your requirements. Currently our preferred brands of inverters are:
We are always looking for the best new products and may provide your quote with other equipment if there is a benefit to you.
Some inverters (notably those produced by SolarEdge) do not manage the panels in groups through “maximum power point trackers”. Instead, each panel has its own “power optimiser” mounted behind the panel to maximise the panel’s yield independently. Without such a system the shading or mismatch of one panel can affect the performance of the system overall. In the case of systems with complicated shading issues, multiple roofs or panel orientations power optimisers ensure your system has an high an energy yield as possible. SolarEdge inverters and power optimisers have numerous benefits:
Microinverters (Micro-Inverters) are an interesting alternative to standard DC-to-AC inverters. With micro-inverters each panel has a dedicated inverter mounted behind the panel to perform the power conversion on the roof. This means all cabling is at grid voltage in AC which is safer and less “lossy” (maintains more power over longer cable runs). Microinverters manage each panel independently and so the shading of one panel will not affect the performance of the system overall. With “string inverters” panels are cabled in sets – if some panels in the string are in shade there will be a voltage drop across the string, decreasing the performance of the whole array. In the case of systems with complicated shading issues, micro inverters can increase your energy yield. Micro-inverters have other benefits including panel-by-panel monitoring of the system via the web. This means, from your computer or smartphone you can view the performance live and historical of each individual panel. Microinverters should expect longer service lives than many string inverters and so tend to come with longer warranties. These drawbacks are that systems are inherently more expensive and there is a reduced economy of scale – systems with more panels need proportionally more microinverters. As an alternative to micro-inverters, we much prefer SolarEdge systems (see above) which use power optimisers. These have many similar to microinverters benefits but at a lower cost, with better features, greater future-proofing and much better economies of scale.
Though all installations have a generation meter displaying the total of all of the electricity your solar pv system has generated, inverters themselves store a lot of information about when the yield was generated, what the peak generation times were and when the sun wasn’t shining! This data can be very useful – particularly if you are planning on optimising how you use of your free electricity. Some inverters have display screens so that you can access data and see graphs of performance history. Other models require add-on monitors that can display this information remotely which can be useful if your inverter is installed in a difficult to access location. Some inverters even connect to the internet to log all performance data with an online portal that you can access from any internet enabled device. Inverters such as those made by Solar Edge and Enecsys even include panel-by-panel monitoring so that you can analyse your system performance in great detail. Beyond this, there are many 3rd party brands who produce excellent monitoring/display solutions making your installation both more manageable and more interesting. Call us today to find out which models best suit your monitoring requirements.
Most standard inverters we install now feature dual or multiple MPPT technology. MPPTs (maximum power point trackers) manage the DC voltages from the panels to maximise the power output in the conversion to AC electricity. Dual MPPT technology gives the possibility of splitting inputs to enable independent maximum power point tracking on each. If your roofs face both east and west, a dual MPPT will ensure maximum production by managing the input from the east and west-facing panels separately to make the most of the power generation as the sun tracks across the sky through the day. These strings can be unbalanced (i.e. on a 16 panel system you may be able to have 7 panels facing west, and 9 facing east) but still only require a single inverter. Roofs and differing angles and orientations can benefit from such a feature too. Also, arrays may consist of a set of panels that are affected by shading, and a set that are in sun throughout the day. Managing the two sets separately even if they are fitted to the same physical roof will also improve overall yield. Systems using micro-inverters (e.g. Enphase) or per-panel power optimisers (such as with SolarEdge) have one MPPT per panel. This a better scenario as the power management is carried across the whole array, at the source of the power variances.
Most inverters we install are transformerless, with the DC voltage from the panels being converted to AC voltage electronically. Typically these inverters offer better pricing, are smaller, lighter and usually much more efficient than galvanic isolated inverters (transformer based). There may be a little more work involved in installing these models but the (sometimes huge) gains in efficiency are worth the effort. Some of the transformerless inverters we install (notably the Steca SG-3600) can achieve a peak efficiency of 98.8%. That means that only 1.2% of the energy from your array is lost in the process of inverting the DC to AC. This energy is lost as heat, meaning that these inverters run much cooler, requiring no fans at all. Fans can make some models noisy when the inverter is working hard. This all said there are some extremely high-frequency transformered inverters that in some circumstances can offer similar efficiency levels to transformerless devices.