Your Guide to Choosing The Best Hybrid Solar System -

Hybrid solar systems are an increasingly popular choice for embracing renewable energy, by combining solar energy systems with a cost efficient use of the public power grid. This article explains the main components of these systems and offers some guidance in choosing the right hybrid solar system for your requirements.

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Table of Contents
The market growth of hybrid solar systems
An introduction to hybrid solar systems
Components of a hybrid solar system
How to choose the right size of hybrid solar system
Final thoughts

The market growth of hybrid solar systems

The global market for solar systems is growing at a very healthy rate, largely due to a combination of increasing public electricity grid costs, and government support for renewable energy systems in the home. The residential market sees more flexibility and cost efficiencies in having a home system that makes best use of solar power as well as finding ways to minimize the need to rely on the public grid.

Because hybrid solar systems have several components, the global market is best measured through the growth of solar hybrid inverters, which are the essential ‘intelligence’ in a hybrid solar system. Looking at the period from to , the global market for solar hybrid inverters is projected at a compound annual growth rate (CAGR) of 9.2%, from US$ 7.39 billion in to around US$ 16.32 billion by .

The global market would expect to see even greater growth if it wasn’t for the high installation cost of the main components, particularly the cost of the inverters, and the lengthy period required to see a return on investment.

An introduction to hybrid solar systems

Hybrid solar systems combine electricity generated from solar photovoltaic (PV) panels with electricity generated from the public utility grid, storing that collected electricity in a battery storage system.

By comparison, hybrid ‘power’ systems combine electricity generated from multiple sources, which can include solar together with wind turbines, hydro-electric generators, public grid, and stand-alone fuel generators.

Whether the hybrid system is using solar only, or integrates mixed sources, the principles are the same. Energy is captured, regulated and stored as direct current (DC) in a bank of batteries, which is then made available to the home by first converting to alternating current (AC) and then used by home appliances as needed.

Power systems that only use only the public utility grid are referred to as ‘tied-grid’, or ‘grid-tied’ systems. Solar systems that are stand-alone, using only the energy from solar panels (and/or other energy sources), and are isolated from the public utility grid, are called ‘off-grid’.

Hybrid solar systems can switch between different grid modes depending on power sources available, and it is this adaptability that makes hybrid solar systems an increasingly popular choice.

In a stable grid system, where public utility power is reliable and consistent, having a hybrid system offers the household some flexibility and cost saving.

• When solar energy is plentiful, the home makes use of this energy for all of its uses, saving on utility costs.
• If the weather is overcast and solar energy is not sufficient, the home can ‘top up’ battery storage, using cheaper rate off-peak public utility electrical supply.
• If solar supply is plentiful, and batteries are full, surplus electricity generated by the home solar system can be fed back to the public grid, which can be purchased or credited by the utility company.

In an unstable grid system, where frequent power cuts or load shedding can mean power is lost for many hours in a day, then the hybrid solar system supplies the home with power from the stored batteries. When grid power is available, it is used to top up the batteries, supplementing the solar power.

Components of a hybrid solar system

The above diagram by Xiamen Nacyc New Energy Company shows each of the important components of the hybrid solar system, the photovoltaic panels, lithium ion battery bank, and the hybrid inverter, showing how they connect to the public power grid and to the home.

Solar photovoltaic (PV) panels

This complete system from United Energy shows a set of four solar photovoltaic cells (PV) panels as well as all other components. The actual number of panels required will depend on the capacity needed, and these are priced at US$ 0.30 to US$ 0.50 per watt.

Solar panels, solar cell panels, or solar photovoltaic panels, are the most visible components of the hybrid solar system. These panels use an array of photovoltaic cells (PV) that excite electrons, which are then passed through a circuit to generate direct current, that can be used directly to power devices, or more commonly to be stored in batteries for later use.

If you want to learn more, please visit our website PERC PV Module.

The solar panels are commonly installed on the roof, either at an angle over the roof tiles, or standing on a flat roof. For a flat roof, the user can angle the panels towards the strongest sunlight, whereas if fitted over the roof tiles, it is normal to select the side that sees the most sun.

The number of panels needed to be installed will depend on the user’s domestic power consumption requirements, the stability of the local grid, and also the likely amount of sunlight available.

Lithium ion battery bank

When energy is captured, either from solar panels or when fed from the grid, it is stored in an array of lithium ion batteries.In smaller systems, batteries may be standalone rather than in a battery cabinet, but will still be connected together as an array.

The amount of battery storage required will depend on the user’s domestic power consumption requirements, and to what extent the user wants to remain independent of the local grid. The more power that is stored, the more electricity available for ‘off-grid’ usage.

Hybrid inverter

Hybrid solar inverters handle all power transfers, regulation and conversion between the batteries, home electrical network, and public utilities power grid.

Modern intelligent power management systems allow the inverter to:

• manage the solar panel charge and storage,
• monitor battery charge levels,
• switch between public grid and battery usage,
• convert stored DC current to AC,
• supply electricity to the home,
• supply surplus power back to the public grid,
• provide real time data to the cloud and to local computers.

It is important to plan for an inverter with the capacity to provide the sufficient concurrent AC conversion that the home will need. As a simple example, microwaves, kettles, ovens and heaters (or air con) can all demand around 2-5 Kw individually. All used together, this will place a very high simultaneous load on the inverter, which can trip if more power is drawn down than the inverter can convert. Intelligent systems will help you to manage excessive demand without causing the system to trip.

Other components

The main components included in a complete system are the solar panels, hybrid inverter, storage batteries, and monitoring software. They also may  include fittings, cabling and in some cases a complete tool kit.

How to choose the right size of hybrid solar system

When selecting the right size of system for the desired use, the supplier should be able to help with calculations. A spreadsheet can help and the supplier may have one to give you.

Key factors to plan will be based on the expected daily and concurrent usage, in KiloWatts. This can be determined from monthly utility bills, to estimate monthly KiloWatt usage, and then this needs to be divided down to a daily amount. This is unlikely to give detailed hours drawdown, but it is helpful to think about peak usage timings rather than average. For example, mealtime cooking can involve using high wattage equipment, oven, microwave, other kitchen appliances, while also using energy for home heating, water heating, tv and home internet.

If the intention is to build surplus supply to feed back to the public grid, then the estimate must allow for that surplus. Of course all of these estimates must ultimately lead to a system that fits within budget, as well as the likely amount of consistent sunlight available. Compromises may well be necessary to find the right size of system.

It is important to note that hybrid solar systems require a large upfront cost, in buying all of the equipment, installation and connection. Return on investment is likely to be over several years, rather than months, so expectations must be managed in building a system on a pure cost savings basis.

Final thoughts

Hybrid solar systems make best use of the combination of renewable solar energy and selective use of public utility grid. The main system component that makes smart combination possible is the intelligent hybrid inverter, with power management systems that give control to the home user.

There is a wide choice of hybrid systems available, all of which include the main components of solar PV panels, storage battery arrays, and a modern hybrid inverter, with smart software. The challenge for the user is to decide what capacity is desired, what use of the public grid is preferred (or necessary in an unstable grid environment), and then what size of system is needed to handle that. Capacity is determined by how many panels are required to capture sufficient sun, how many storage batteries are required to hold enough power for all uses, and what DC/AC conversion capacity the inverter can handle for any concurrent demand.

Cost is an important factor as most of the cost is upfront investment, in buying and installing the components, and ROI is likely to be over a long period. However, where there is an unstable power grid, a high investment cost may be more acceptable for the necessity of regular power. Suppliers may price by complete set, but many price by US$ per watt, so again it is important to know the necessary capacity.

Blurb time!

Well, I'll start the default answer to these questions and we can work from there. Here's you To-Do list:

1: Power audit! This will give you some important information on how big your inverter needs to be as well as how much battery capacity you'll need. There is a link in the FAQ section (I think, or someone here will post it shortly) so fill in the blanks and see what it comes up with. You'll probably need some sort of Kill-A-Watt to get accurate measurements. Are you going to be running a 12v system? 24v system? 48v system? What are the specs on your solar panels? VoC? Vmp? Being as this is a new build, throw together a wish list of what you want and estimate on the high side.

1a: Where do you live? Speccing out a system for Scotland is a LOT different numbers than Arizona due to the amount of light you actually get. Someone here can post the link to the PVwatts.com or JCR Solar Uber-Sun-Hours calculator sites to help figure out how much you'll have to work with. That will be a box in the Power Audit form.

2: Parts list: You don't need a make & model list, just a parts list to start from for reference. You'll need an inverter, a MPPT charge controller, fuses, shunt, buck converter, batteries, wire, etc. Once you have a basic list it can be fine tuned to make & models after that. If you're looking at the All-In-Ones check for correct voltage outputs (120v or 240v Split Phase for North America, 220v Single Phase for European type areas) and make sure it has enough capacity for a little bit of growth and fudge factor.

3: Budget!: Steak is great but doesn't mean anything if your wallet says hamburger. Figure out what you're able to spend now vs what you'll have to cheap out on now and upgrade later.

4: Tape measure! Figure out where you're going to stick all the stuff you'll need. A dozen AH batteries sounds great until you're sleeping on the floor because there's no room left for a bed. Is there a compartment that can house all this stuff? Will the server rack batteries fit? Are you going to have to make space? Physics can be pretty unforgiving.

5: Pencil out what you think you need and throw it at us so we can tell you what you've missed (because we ALL miss stuff the first go-round ) and help figure out which parts and pieces you're going to want to get.

Well that's the thing about solar systems, there is no 1-Size-Fits-All answer. Your system will need to be designed to fit YOUR needs. When you design and built the system, it's not going to be the perfect system for me, or Will or 12vInstall or anyone else, but it Will be the right system for You and that's the goal.

As for where to get started, let me throw my standard blurb in here to help point you in the right direction. There's going to be a lot of math and research involved, but that's going to be a LOT cheaper than just buying parts off of someone's list and finding out that it doesn't do what you need.

Don't panic on the Power Audit, you'll actually be doing that a few times. When you do the first pass put in ALL the Things that you might want. AirCon? Sure. Jacuzzi? Why not. MargaritaMaster-? Go for it.

The second pass will be the "I Absolutely Need This To Survive" list that isn't going to have much on there.

The third pass will be the "This is what is realistic" audit that you'll use to design the rest of the system.

The Power Audit is going to tell you 3 primary things: 1: How big does your inverter need to be to power your loads? 2: How much battery bank do you need to last $N number of days with krappy weather? and 3: How much solar panel will I need to install to refill those batteries in a 4 hour day (the average usable sun hours rule-of-thumb).

Once you know what you Want and what you Need and what your budget can Afford there will be somewhere in that Venn diagram where those three things meet.

After that, THEN you can start looking at parts.

Yes, it's a long drawn out process, but it's worth it in the end. Not every house has the exact same floorplan, not every vehicle is the same make & model, and not every solar system is designed the same.