estimating grundfos sqflex performance

SystemSystem Posts: 2,511 admin

I'm trying to estimate the flow rates I can expect from a Grundfos SQFlex pump throughout a solar day. I have the performance curve and the head and the rated wattage of PV panels that will be connected. I have already included derate factors for the PV panels. Now I want to know how many liters I can expect to pump in a day. I've tried using the Peak Sun Hours number for my region, but am worried that it doesn't accurately represent the performance of these pumps. My concern is that the Peak Sun Hours represent the amount of solar energy that could be captured in batteries, but I know there is some energy in the morning and evening that could be stored in batteries, but can't be utilized by the SQFlex. How do I factor that into my calculations?



  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: estimating grundfos sqflex performance

    what you may be refering to as peak sun hours you may in fact be refering to full sun hours. a full sun hour is solar radiation coming in at a rate of 1000w/meter^2. you are right that the early morning and late evening adds up and it may take quite a few of those hours to equal one full sun hour. this depends on your location just how much you are really getting at any particular time of year.
    if you've already got the info for full sun hours in a day then you already have your answer that you most likely won't get anymore. it can get worse than that figure at times with cloudy or rainy days. also if you charge a battery to store the power, this is a loss as well by about 15-30% depending on your specific battery and other losses involved. so in addition to making up for those losses you will have to realize that you may not be able to run the pump 24/7 unless the pvs and batteries can supply that much power to be stored, overcoming all losses, for to be called upon for later use in the pumps.
    if you pump it all during the sunny periods, this may eliminate the need of the batteries and that extra step and loss.
    some of your other specific questions i can't answer as it should be in the literature of the pump as to what flow rates are possible and any inclinations involved. remember the pvs are only a limited power source. if the pvs deliver all power needed then it is strictly up to the specs of the pump.
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