Hot Water - Solar Tubes, Solar Flat Plate or Solar PV System for Geyser




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  1. #1
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    Default Hot Water - Solar Tubes, Solar Flat Plate or Solar PV System for Geyser

    Hi to.

    ON the advice trail again - hot water and geysers.

    On doing my homework, and lots of it, we have worked out we have to go solar to reduce our hot water heating costs.

    We have 2 options here - heat the water using the sun or provide electricity from PV panels to run the element in the geyser.

    So first question:

    Which is better - solar tubes or flat plate that heats the water going into the geyser or PV panels making electricity that energises the element in the geyser?

    And if you say heating the water with Tubes and Flat Plate, then next question is:

    Which is more efficient - evacuated tubes or flat panel if we go the heating the water route?

    Then we have run into another variable - some machines are top loaders that take hot water from the geyser, and some are front loaders that only take in cold water and have elements to heat the water.

    To me if you going to heat the water, no matter which method we use - tubes or make electricity, you have to have a machine that allows you to put hot water into it, like a top loader.

    And if we really want front loaders that heat up the water, then we have to not worry at all about the geyser and go for a full PV panel and inverter system to supply electricity to the laundry.

    Confusion. Any input appreciated by anyone who has walked this route.

    Obvious to me that we have to first up decided if we are going top loaders of front loaders. Only then can we really decide on which solar route we going to take.

    thanks.
    Karooview Cottages
    Prince Albert
    www.karooview.co.za

    4x4 and Caravan Friendly
    Outdoor plug points

  2. #2
    Join Date
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    Default Re: Hot Water - Solar Tubes, Solar Flat Plate or Solar PV System for Geyser

    Normal domestic application ?

    Or for the Lodge ? How many rooms in the lodge ?

    Have you considered a single hotwater system, with a circulating pump and having hot-water-on-demand for your guests ?



    For DOMESTIC :
    Evacuated tubes provide the most hot water per square meter installation.
    Due to the sub-zero temperature you see during the winter you NEED an "indirect system", ie a glycol type solution that pass through the plat plates or evacuated tubes, with another heat exchanger to heat the water in the geyser.
    I would certainly recommend a "pumped" system, thus allowing you absolute control to ensure you dont syphon away heat during the cold nights, AND allowing you better control to prevent boiling the water in the geyser during summer

    All this said, we installed a dual element system with PV panels three years ago. YES, very happy with our system !!! We measured the electricity to the geyser, before and after the installation, the system already paid for itself.
    Main advantages:
    - piping a traditional system was NOT an option due to the layout of our house. Running wires 15m from the PV panels was very easy.
    - PERFECT temperature control !!! Solar hot-water systems worst problem is the constant over-heating ....

    Only disadvantage - the PV panels require about twice the roof space ....



    COMMERCIAL - if you want to use this for the guest house ....
    Completely different set of parameters to consider.
    - how many guests ?
    - when do they arrive ? At the end of the day ? Nice long bath/shower after a day of traveling and you have a lot of cold water in your geysers ... and very unhappy guests tomorrow morning !
    - A heat pump unit makes the most sense in terms of the night time water heating costs .... with the major risk of the unit noise upsetting clients .... IF you go this route, make sure you get a very quiet unit !! Also place it far far away from any guest bedrooms.
    - For a guest house a single larger hot water tank makes the most sense ... IF the piping allows for this .... doubt you want to re-pipe the house.


    One would need to know more about your intended installation in order to give more feedback.

  3. #3
    Join Date
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    Friemersheim, Southern Cape
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    Default Re: Hot Water - Solar Tubes, Solar Flat Plate or Solar PV System for Geyser

    Quote Originally Posted by LLTHB View Post
    Then we have run into another variable - some machines are top loaders that take hot water from the geyser, and some are front loaders that only take in cold water and have elements to heat the water.

    To me if you going to heat the water, no matter which method we use - tubes or make electricity, you have to have a machine that allows you to put hot water into it, like a top loader.

    And if we really want front loaders that heat up the water, then we have to not worry at all about the geyser and go for a full PV panel and inverter system to supply electricity to the laundry.

    Confusion. Any input appreciated by anyone who has walked this route.

    Obvious to me that we have to first up decided if we are going top loaders of front loaders. Only then can we really decide on which solar route we going to take.

    thanks.
    Do you have a washing machine in each cottage, or a washing room for all with different type of machines?

    Edit: your other thread answered the question
    Last edited by Prof; 2018/08/05 at 05:43 PM.

  4. #4
    Join Date
    Aug 2015
    Location
    Prince Albert
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    Default Re: Hot Water - Solar Tubes, Solar Flat Plate or Solar PV System for Geyser

    Thanks for those replies.

    Having had a good look at the "business case" - this is a laundry and the only decisions that need to be made must concern the business of the laundry. Then how we run it more efficiently to cut costs is what the solar route is going to achieve - the financial case so to say.

    So, from a laundry point of view - the best wash with the cleanest results and the least damage to the linen and clothes are front loaders.
    So the decision is made to go front loader. At present we have 4 machines in the laundry, 2 front loaders and 2 top loaders. We do also have 2 spare front loaders on hand, so the plan is to install the spare front loaders and sell the top loaders out of hand.

    Front loaders though cannot take hot water coming in. Warm water yes, but not 60 degree water. So we will plumb them up to the cold water system and power them through a grid tie system that is heavy on panels and no batteries. As long as they are not all started at the same time, we can generate enough power from 9am to do all the washing and then we will have power in the afternoons for tumble driers.
    Dont need the battery back up as we can go a week without having to t


    This will allow us to turn off the geyser in the laundry. Perhaps we will install a on demand hot water system, under counter Kwikot type system. Or we will convert it to a solar geyser system with glycol tubes, a pump, Geyserwise controller. The present geyser is well wrapped and insulater

    Ironing of the laundry will also be able to be done on the grid tie system.

    Sheets must be clean, crisp, ironed and slightly starched.

    So this seems to have sorted out this problem and this is the road we will go with this.

    Busy looking at a Goodwe inverter and 330watt panels.

    The financial case is the system will make a return on investment of about 6 years.
    System makes 25 kilowatt hours a day, cost here is R2.03 per, so just over R50 a day is generated.
    R1500 a month. R18 000 a year savings.
    No batteries to replace as well.

    So on this the financial return is really good.

    Now I need info on a wind turbine for our main house. Wind can blow here in the summer, nice to be able to charge the house batteries at night. Looking for a wind tester - small station you install where you planning to put the turbine up, allows you to evaluate the feasibility of going the turbine route.

    Cheers.
    Karooview Cottages
    Prince Albert
    www.karooview.co.za

    4x4 and Caravan Friendly
    Outdoor plug points

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