About
gowith.solar is built by Mark Phoenix and James Phoenix, two independent developers. We do not install solar, we are not owned by anybody who does, and nobody pays us for a recommendation.
Why this exists
Most solar calculators ask for a postcode and a roof direction and hand back a payback figure with no working shown. The number is doing a great deal of quiet guessing on your behalf, and the guesses are exactly where two calculators disagree. Worse, the calculator usually belongs to somebody selling the panels.
We wanted the version that shows its arithmetic, so you can find the assumption you disagree with and see what changing it does to the answer. That is the entire product.
What the calculator will not do
- It will not inflate future savings. Every figure is in today’s prices. Installers commonly quote twenty-five year totals escalated by an assumed energy price rise, which makes the number look far better than it is. We do not do that, and the year-on-year increments are identical across the projection so you can check.
- It will not discount to present value either. A discount rate is the most opinionated number in any model of this kind, and choosing one is putting a thumb on the scale. We decline to choose. That means the figures are in real terms and are not a present value, and we say so rather than implying otherwise.
- It is not AI. It is a deterministic model. The same inputs give the same answer every time, which is the property you actually want from something you are making a five-figure decision on.
- It will not invent a number. No made-up ratings, no testimonials, no user counts. Where a figure cannot be sourced, we leave it out and say why.
How this is paid for
The site carries an Octopus Energy referral link, shown as a banner that says plainly that we both get credit if you switch through it. That is the only commercial relationship on the site today.
It does not touch the model. The calculation runs identically whether or not you ever click it, and no supplier pays to be mentioned, included or ranked anywhere here. If that ever stops being true, this paragraph changes first.
Corrections
If you think a number here is wrong, we would rather know. The model is the product, and a quiet error in it is worse than an obvious one. Posts carry the date they were published, and anything revised carries the date it changed rather than being silently backdated to look fresh.