I'm stuck, need help!

[LouiseSJPP]

I thought I could find my way around a solar system design, but I'm utterly baffled now as to how it would work.

I am planning a wood-fired spa pool. I want to provide power for the 80 watt filter circulation pump for several hours a day. I need power on hand to run the 1kW jet pump motor as needed, while the spa is being used. I foresee using any 'spare' power to background heat the spa water, with a 1 to 1.5kW heater, so that heat-up time with the stove is reduced, and hopefully, at the height of summer, the water temperature might be maintained with electricity alone.

If the system could be arranged to provide some kind of back-up power to the house for essentials only in a mains power cut, this would be great.

This all seems very simple as a system, but the moment I start looking into it, I see that I have no idea how to make it all perform the way I want, and as I don't know how to arrange it all, I cannot begin to specify the components.

Can anyone advise on baby steps, please?

 

[hwy17]

120v or 240v pumps and what part of the world are you in?

 

[wpns]

Well, you've got a bit of feature creep there, from 80 watts to 1KW (plus starting surge) plus another 1.5KW, to house essentials, but it's all doable. I mean you could even forgo the batteries and run the circulation pump directly off a solar panel with an appropriate controller.

Do you already have the spa, or will you be building your own, or could you modify it to run (say) the jet pump from the grid while the solar does the circulator and heating?

Kinda depends of you want to start small and grow the system, or do it all at once and avoid too much 'learning from your mistakes'. Which also depends on your budget.

IMHO you are into a 3 to 6KW inverter, something like 5-10 KWHR of battery, and 500-1000 watts of solar panel, though for the panels it'll be whatever you can afford, and whatever your locality will allow. A quick glance around St Jean Pied Du Port in France doesn't show a lot of solar.

Do you have net metering? If your solar controller (or All-In-One) has a 'dump load' feature, then it's trivial to heat the water with any spare power, if not the logic gets tortuous...

 

[Mattb4]

Solar mission creep. Hardly simple when you add more and more things you want to power. If you grid tie your solar it would be simple but than you would need to come up with a means of backup. If you run off grid your loads can not be connected to both the off grid and the on grid at the same time.

You could use an off grid setup with a critical loads panel that feed your Hot tub and a few essential circuits.

 

[LouiseSJPP]

Do you already have the spa, or will you be building your own, or could you modify it to run (say) the jet pump from the grid while the solar does the circulator and heating?

Spa ordered, jet pump included. I'd thought of running the jet pump from house mains to avoid that big start load and the need for battery capacity, but that would mean two out-of-phase voltages within the spa, with a shock potential of 400V. Not keen. Looking to keep mains and solar circuits physically very separate.

Kinda depends of you want to start small and grow the system, or do it all at once and avoid too much 'learning from your mistakes'. Which also depends on your budget.

I'm an all-at-once kind of girl! Plus, buying the right kit in the first place is cheaper than continual upgrading, although there is some scope for a series-parallel array which would allow much of the system to split down the middle, and be done in two halves.

IMHO you are into a 3 to 6KW inverter, something like 5-10 KWHR of battery, and 500-1000 watts of solar panel, though for the panels it'll be whatever you can afford, and whatever your locality will allow. A quick glance around St Jean Pied Du Port in France doesn't show a lot of solar.

I'm over the border in Spain and there's a fair bit of solar springing up now. As yet, Spain has no planning law on solar.

Yes, I'm looking at a 2.4kWp array which would yield 1.22kW in summer. Max summer production would be 10kWhr per day, so battery size of 5 to 10 would feel right. A 3kW invertor would run the motor, circ pump and a 1.5kW water heater. Put a change-over switch between heater and motor (to run only one at once) and I could run a 3kW water heater, which is cheaper to buy because they're standard. Above 3kW, invertors and wiring starts to get expensive.

Do you have net metering? If your solar controller (or All-In-One) has a 'dump load' feature, then it's trivial to heat the water with any spare power, if not the logic gets tortuous...

Need to look more into this, it's unknown territory foe me. At least you've given me some search terms

 

[wpns]

Sounds like you have a plan, lots of expertise here if you need advice. Look for systems that can be paralleled so you can add more batteries, inverters, panels as you gain some experience and future uses crop up.