DIY: Designing a Solar-Diesel-Hybrid-System Easily with Sunny Design
Author: Darvin Tocmo Date Posted:1 February 2017
It is never easy to design a solar-diesel-hybrid system. Meteorological data and electrical parameters are just two of the many values that have to be taken into account in doing this. Fortunately there was a free tool called Sunny Design that makes designing a solar-diesel hybrid system super easy. In this article we will guide you on how to design a hybrid system with Sunny Design to easily create offers for your customers, project documentation or suggestions for improvement for your existing diesel grid. This is meant to be a guide on planning a hybrid system with Sunny Design. If you like, you can open Sunny Design in a second browser window and try all the steps yourself. Enjoy planning your own solar-diesel hybrid system. Login First of all, the advanced features of Sunny Design, such as designing hybrid systems, are only available to registered users. So you have to register and lo gin to start planning your first hybrid system. It is free of charge. A Sunny Design registration provides you with additional advantages, including an online place to store your projects, so that you can design multiple projects, subsequently change them or duplicate popular designs for new projects. You are also able to personalize the design outcomes to make offering solar hybrid systems to your customers even easier. Welcome screen The welcome screen allows you to manage your projects. You can add new projects, handle your projects and templates, and adjust the very basic settings. You can store your own locations, load profiles and price lists for use in all of your projects. To get started quickly, I would suggest you skip these advanced functions for the moment and just start creating your first new hybrid project. You can easily dive deeper into all the options of configuring Sunny Design later on. Project type Sunny Design supports different solar project types such as rooftop solar systems, large-scale solar plants, systems with self-consumption, island systems and solarhybrid systems. You can use Sunny Design to design the layout for all of these systems. This article focuses on hybrid systems, so please choose PV (photovoltaic) hybrid system as your projects type. Basic settings On this page, you are able to set many basic parameters for the project. You can define a project name to easily identify your project from other projects you have created as well as the location of the project. Now you have to choose for which voltage level you want to design your hybrid system. This already narrows down the choice of solar inverters for your project. If you choose “low voltage” (less than 280 V per phase) here, only low-voltage inverters can be used in your project. If you choose “medium voltage” you are able to use either a multitude of decentralized small inverters (this is useful as maintenance only affects small parts of the system or in case where the solar field is scattered with physical distance between the field segments, but is a little bit more expensive) or centralized large inverters up to 2.5 MW (better efficiency, slightly lower costs). The “Advanced project data” section contains many more options for fine-tuning. The location, basics for profitability calculation, temperature settings, electrical inverter connection and line losses can be adjusted to get a better profitability estimate at the end. Project details can be given, which are used to personalize the printable report that can be downloaded when the project design is complete. Meteorological data For a realistic profitability analysis, it is very important to set the correct location. You may choose a place that is near to where your hybrid system is to be built. The locations provided by Sunny Design are linked to meteorological data like irradiation and temperatures so that the solar energy generation can be estimated accurately. You can proceed to the next page by clicking “Define load profile”. Load profile Here you can define the load characteristics you expect your hybrid grid to have. For ease of use, there are some load profiles provided that you can simply apply. Or, if you have already loaded data from the grid of your project, you can simply import this data. You can set the annual consumption here. The load profiles are scaled so that the resulting load profile fits the annual consumption you have set. The three graphs below the load configuration show the load powers resulting from profile and scaling. Create your own load profile You can also create your own load profile easily. So that you can reuse it in other projects, you can give your load profile a name and a description. The annual energy consumption is the energy amount that the profile is scaled to fit. Now you can define season durations for summer and winter. Spring and fall are added accordingly. Now you can add daily profiles and go into as much detail as you like. In the picture on the right, there is just one profile for weekdays and another for weekends. But you can easily add more and create profiles for individual weekdays and seasons. Genset configuration On this page, you can configure the gensets that are available, as well as the operation conditions they can be driven in. Some values affect profitability significantly. A minimum genset load can be defined for each genset. This is the minimum power at which a genset can be continuously driven. This especially affects how much solar power/energy can be integrated into the grid at peak times. When the genset reaches this minimum genset load limit, the solar power is curtailed. The load-related minimum power defines when another genset is started in the Sunny Design simulation. The preset value is 110% – this means that if the load rises and the nominal power of the currently running genset(s) can provide less than 110% of the current load, another genset is started. The “Minimum PV power to be expected” value determines how large a drop in solar production can be attributed to clouds. The preset value of 20% is based on experiences in different systems and should stay untouched. Let’s continue with the configuration of the solar-diesel hybrid system on the next page. PV share proposal Sunny Design now performs a quick profitability analysis and shows which nominal solar power provides a financial advantage. Depending on load and gensets, the PV system has to be curtailed the more nominal solar power is installed. The green field indicates where the financial advantage rises with more solar power, whereas the red field shows where the financial advantage does not rise significantly with more nominal power due to curtailment. This page mentions a technical maximum of 60% solar power of the apparent power of the gensets. This is only true as long as no storage system is involved. We have different systems running at a PV share of as much as 90% with batteries, but storage solutions are not yet included in Sunny Design. Solar inverter configuration Now it is time to configure the PV system. The PV share proposal already provides a number of solar modules is already provided. You are free to choose specific manufacturers (Sunny Design has a large module database) or to split the solar field into smaller parts. Next you can configure the solar inverters. There are many different inverter models and depending on your design, there could be a large range from 1 to more than 100 inverters needed to realize your design. To make this as easy as possible, there is a button “Design suggestions”-button that gives a recommendation on which inverters to use – default is sorted by profitability. Just select a suggestion you like and click on “Adopt design”. That’s it! Now you can see how the inverters you selected will perform in your hybrid system. Wire sizing You can optimize your design further by selecting appropriate wiring for your hybrid system. Sunny Design calculates the losses for energy transportation on cables with the selected cross sections. If you have selected this during project configuration, this will also be taken into account in the profitability analysis. So choosing another cable cross-section or material can sometimes compensate for the higher costs. Wiring can be configured for the DC side as well as the AC side with or without sub-distribution. Profitability analysis Now all the information is compiled and we can see what we can expect from the solar-diesel-hybrid system in terms of economic advantage compared with the previous genset-only grid. Topmost, there are the pure numbers. What are the investment costs and how long does amortization take? And which financial advantages does the hybrid system provide? You will find answers to this in the “Profitability” section. In the “cash flow” section the graph in the middle is particularly interesting as it shows the break-even point at which the hybrid system outperforms the conventional genset system and starts saving real money. The graphs below show the sensitivity of the fuel price assumptions on the amortization period. The more expensive the fuel gets, the smaller the amortization period will be. Results overview On this page, Sunny Design reshows all the settings made during the design process, which are displayed as a one-page overview. Here you can check your settings again to ensure they are valid. Proceeding to “Project documentation” will provide you with a pdf download that contains the project setup and the profitability analysis. You can use this to make a suggestion to your grid utility on how to improve your grid or as project documentation for your own customers. Summary I hope this article helps you to design a solar-diesel-hybrid-system with Sunny Design in easy way. If you have any more questions, feel free to send a comment or share your experiences with Sunny Design for Hybrid Systems. We'd love to hear from you!